Magnesium alloy(AZ91D)composites reinforced with silicon carbide particle with different volume percentage were fabricated by two step stir casting process.The effect of changes in particle size and volume fraction of...Magnesium alloy(AZ91D)composites reinforced with silicon carbide particle with different volume percentage were fabricated by two step stir casting process.The effect of changes in particle size and volume fraction of SiC particles on physical and mechanical properties of composites were evaluated under as cast and heat treated(T6)conditions.The experimental results were compared with the standard theoretical models.The results reveal that the mechanical properties of composites increased with increasing SiC particles and decrease with increasing particle size.Distribution of particles and fractured surface were studied through SEM and the presence of elements is revealed by EDS study.展开更多
To synthesize graphene economically and efficiently,as well as to improve the interface bonding between graphene and metal and to recede the aggregation issue of graphene,in this work,an easy and scalable bottom-up st...To synthesize graphene economically and efficiently,as well as to improve the interface bonding between graphene and metal and to recede the aggregation issue of graphene,in this work,an easy and scalable bottom-up strategy for the mass production of metal nanoparticles modified graphene nanoplates(GNPs)was proposed.Cu nanoparticles modified GNPs(Cu-GNPs)and Ni nanoparticles modified GNPs(Ni-GNPs)were fabricated through this method,and then compounded with Al via ball milling technique.The asobtained Ni-GNPs/Al composite showed simultaneously improved strength and toughness compared with unreinforced Al,while the Cu-GNPs/Al composite presented a greater strengthening effect.The microstructure and interface of the two composites were carefully characterized and investigated to reveal the difference.First principle study was also adopted to explore the binding energy of different interface structures.This study could provide new insights into the fabrication of GNPs and the control of interface in GNPs/Al composites.展开更多
Some properties of the Fe-based P/M composites sintered and reinforced by infiltration with Cu-Sn alloy were described.It is shown that the hardness of the sintered material is 2.5 times lower,tensile strength is 1.7 ...Some properties of the Fe-based P/M composites sintered and reinforced by infiltration with Cu-Sn alloy were described.It is shown that the hardness of the sintered material is 2.5 times lower,tensile strength is 1.7 times lower and the wear resistance is 2.5-3.3 times lower in comparison with those of the infiltrated material.The presence of pores on the friction surface of the sintered material affects the features of the wear process.Due to the specific morphology of copper in the infiltrated material,the phenomenon of selective mass transfer is observed and worn surfaces have a spongy-capillary texture.展开更多
The mechanical and wear behavior of copper-tungsten disulfide（Cu/WS_2） composites fabricated by spark plasma sintering（SPS） and hot pressing（HP） was investigated, comparatively. Results indicated that the additi...The mechanical and wear behavior of copper-tungsten disulfide（Cu/WS_2） composites fabricated by spark plasma sintering（SPS） and hot pressing（HP） was investigated, comparatively. Results indicated that the addition of lubricant WS_2 substantially reduced wear rate of the Cu matrix composites fabricated by SPS,and the optimum content of WS_2 is 20 wt% with regard to the wear behavior. However, it affected a little to the wear rate while dramatically decreased the friction coefficient of the composite fabricated by HP.This difference in friction behavior of the self-lubricating composites fabricated by the two techniques was closely related to their different mechanical properties. Severe interfacial reaction occurred during spark plasma sintering, leading to brittle phase formation at interface.展开更多
The thermal properties of Mg alloys require further optimization to encounter the increasingly severe heat dissipation demands of high-power densities and highly integrated electronic components.In this study,a novel ...The thermal properties of Mg alloys require further optimization to encounter the increasingly severe heat dissipation demands of high-power densities and highly integrated electronic components.In this study,a novel strategy of reaction-tunable diffusion bonding(RDB)was applied to manipulate the inter-facial reaction in the multilayered Cu mesh/ZK61 Mg foil composites.The displacement of the punch was utilized to quantify the degree of reactive diffusion with adjustable,visible,and high flexibility.The inter-face was artificially manipulated to produce the fluid Mg-Zn eutectic liquid phase filling the interfacial gap at high temperature for a short time,followed by diffusion bonding at low temperature.The thermal conductivity of the composites first increased and then decreased,which was synthetically affected by the amelioration of metallurgical bonding and the moderately reactive consumption of Cu.The reinforcement Cu was converted from the Hasselman-Johnson model to the Rayleigh model,reflecting the optimization of the interfacial bonding quality.The composites with thermal conductivity and lightweight synergy were fabricated successfully.Therefore,RDB is a progressive technique,shedding lights on the innovative lightweight metal matrix composites with high thermal conductivities relevant to the 5G communications and new energy vehicle industries.展开更多
Porous Cu-Sn-Ti alumina composites were fabricated by sintering Cu-Sn-Ti alloy powders, graphite particles, and alumina hollow particles agent. The effects of the pore structure and distribution on the composites stre...Porous Cu-Sn-Ti alumina composites were fabricated by sintering Cu-Sn-Ti alloy powders, graphite particles, and alumina hollow particles agent. The effects of the pore structure and distribution on the composites strength were evaluated. Different pore distributions were modeled by using finite element analysis to investigate the tensile strength of the composites. Furthermore, a fractal analysis-based box-covering algorithm was used on the Cu-Sn-Ti alumina composites topology graphs to better investigate the pore structure and distribution. Results obtained show that different sizes and concentrations of alumina hollow particles could result in different porosities from20% to 50%. A larger pore size and a higher pore concentration reduce the strength, but provide more space for chip formation as a bonding material of a grinding wheel. The body-centered pore structure of the composites shows the highest stress under a tension load. The original composites topology graphs have been transformed to ordered distributed pore graphs based on the total pore area conservation. The information dimension magnitude difference between the original topology graphs and the ordered distributed circulars graphs is found to be linear with the Cu-Sn-Ti alumina composites strength. A larger difference renders a lower flexural strength, which indicates that uniform ordered distributed pores could benefit the composites strength.展开更多
A novel metal matrix composites(MMC)with Mg matrix reinforced with natural filler in the form of Didymosphenia geminata frustules(algae with distinctive siliceous shells)are presented in this work.Pulse plasma sinteri...A novel metal matrix composites(MMC)with Mg matrix reinforced with natural filler in the form of Didymosphenia geminata frustules(algae with distinctive siliceous shells)are presented in this work.Pulse plasma sintering(PPS)was used to manufacture Mg-based composites with 1,5 and 10 vol.%ceramic filler.As a reference,pure Mg was sintered.The results show that the addition of 1 vol.%Didymosphenia geminata frustules to the Mg matrix increases its corrosion resistance by supporting passivation reactions,and do not affect the morphology of L929 fibroblasts.Addition of 5 vol.%the filler does not cause cytotoxic effects,but it supports microgalvanic reactions leading to the greater corrosion rate.Higher content than 5 vol.%the filler causes significant microgalvanic corrosion,as well as increases cytotoxicity due to the greater micro-galvanic effect of the composites containing 10 and 15 vol.%diatoms.The results of contact angle measurements show the hydrophilic character of the investigated materials,with slightly increase in numerical values with addition of amount of ceramic reinforcement.The addition of Didymosphenia geminata frustules causes changes in a thermo-elastic properties such as mean apparent value of coefficient of thermal expansion(CTE)and thermal conductivity(λ).The addition of siliceous reinforcement resulted in a linear decrease of CTE and reduction in thermal conductivity over the entire temperature range.With the increasing addition of Didymosphenia geminata frustules,an increase in strength with a decrease in compressive strain is observed.In all composites an increase in microhardness was attained.The results clearly indicate that filler in the form of Didymosphenia geminata frustules may significantly change the most important properties of pure Mg,indicating its wide potential in the application of Mg-based composites with a special focus on biomedical use.展开更多
High-strength metallic foams have a wide range of applications in engineering as lightweight structural and energy-absorbing materials.However,it is challenging to obtain metallic foam with both good energy absorption...High-strength metallic foams have a wide range of applications in engineering as lightweight structural and energy-absorbing materials.However,it is challenging to obtain metallic foam with both good energy absorption performance and high strength.Here,we developed a novel metal matrix syntactic foam fabri-cated with AlCoCrFeNi_(2.1) eutectic high entropy alloy and alumina cenospheres that exhibits a remarkable combination of high strength and energy absorption performance under both quasi-static and dynamic compression.The porous structure of syntactic foam fully exploits the properties of the AlCoCrFeNi_(2.1) alloy matrix with a unique FCC/B2 dual-phase eutectic microstructure and thus yields exceptional per-formance.We discovered that this dual-phase microstructure not only provides high strength but also allows the pores to collapse in a progressive and diffusive way,which enables the formation of a high and smooth energy absorption platform.It is found that the heterogeneity between the two phases in the matrix can provide back stress strengthening,and it also induces multiple micro shear bands and microcracks as additional energy dissipation modes as the deformation proceeds.This unique mechanism ensures the strength of microstructures and makes them fracture promptly,which causes the balance of strengthening and softening on the macro scale.This work opens the avenue for developing advanced high-strength lightweight structural and energy-absorbing materials.展开更多
The 5.0 vol.%GNP/2024Al composites were prepared by accumulated shear deformation combined with heat treatment,i.e.the thermomechanical treatment(TMT).The results showed that homogeneous distributed GNPs that aligned ...The 5.0 vol.%GNP/2024Al composites were prepared by accumulated shear deformation combined with heat treatment,i.e.the thermomechanical treatment(TMT).The results showed that homogeneous distributed GNPs that aligned along the plastic deformation direction were obtained by six-pass drawing in the solution heat treatment state.The introducing of high-density dislocations in Al matrix by multiple drawing resulted in enhanced nucleation of precipitates and subsequent uniform growth during ageing.Consequently,ultra-strength GNP/2024Al composites,with yield and ultimate tensile strength 482 and571 MPa,respectively,were achieved.The high strength was attributed to homogeneous dispersion of undamaged GNPs,fine and dispersed precipitations and work-hardening effect.This work demonstrated that TMT could act as a feasible strategy for preparing high-performance GNP/Al composites.展开更多
The constant increase in power and heat flux densities encountered in electronic devices fuels a rising demand for lightweight heat sink materials with suitable thermal properties.In this study,discontinuous pitch-bas...The constant increase in power and heat flux densities encountered in electronic devices fuels a rising demand for lightweight heat sink materials with suitable thermal properties.In this study,discontinuous pitch-based carbon fiber reinforced aluminum matrix（Al-CF） composites with aluminum–silicon alloy（Al–Si） were fabricated through hot pressing.The small amount of Al–Si contributed to enhance the sintering process in order to achieve fully dense Al–CF composites.A thermal conductivity and CTE of 258 W/（m K） and 7.0 9 10-6/K in the in-plane direction of the carbon fibers were obtained for a（Al95 vol%＋ Al–Si5 vol%）-CF50 vol%composite.Carbon fiber provides the reducing of CTE while the conservation of thermal conductivity and weight of Al.The achieved CTEs satisfy the standard requirements for a heat sink material,which furthermore possess a specific thermal conductivity of 109 W cm3/（m K g）.This simple process allows the low-cost fabrication of Al–CF composite,which is applicable for a lightweight heat sink material.展开更多
The design of flexible composite electrodes has become the top priority in energy storage devices for the development of future wearable intelligent electronics.However,searching for fully integrated,ultrathin flexibl...The design of flexible composite electrodes has become the top priority in energy storage devices for the development of future wearable intelligent electronics.However,searching for fully integrated,ultrathin flexible composite electrodes with satisfying electrochemical performance is still a major challenge.Herein,we introduce a nanoporous gold metallic glass(MG) ribbon-based composite electrode with excellent electric conductivity,mechanical flexibility,and extra capacitance by integrating polypyrrole(PPy) into wrinkled nanoporous ribbon(NPG@MG).The freestanding,ultrathin,highly conductive and flexible" nature of the composite electrode prevents the conducting polymer from structural instability resulting from the volume swell and shrink during the charging/discharging circulation,and the packed PPy provides protection for the wrinkled topology on the surface of the MG ribbon.The capacitance of pure NPG@MG-PPy composite electrode reached 393 mF·cm^(-2).The ultra-thin all-solid-state flexible supercapacitor demonstrates an excellent capacitance of 172 mF·cM^(-2)(14.8 F·cm^(-3)),accompanied by a superior cycling capability after 8000 charge/discharge cycles attributed to mechanical flexibility.The areal energy density also reached 0.74 mWh·cm^(-3)(9μWh·cm^(-2)) at a power density of 1 μW·cm^(-2).This work provides valuable concepts on the design of PPy-based hybrid materials for flexible energy storage systems with greatly enhanced electrochemical performances.展开更多
In this research,the wear and mechanical responses of pure magnesium-graphite(Mg-Gr)composite have been investigated aiming to get the optimum composition of reinforcement.The composite materials were fabricated by me...In this research,the wear and mechanical responses of pure magnesium-graphite(Mg-Gr)composite have been investigated aiming to get the optimum composition of reinforcement.The composite materials were fabricated by mechanical alloying.The percentage of graphite reinforcement was chosen as 3,5,7 and 10 wt.%to identify its potential for self-lubricating property under dry sliding conditions.The mechanical properties including hardness,tensile strength and flexural strength of the composites and the base material were tested.The wear tests were conducted by using a pin-on-disc tribometer.The results show that the mechanical properties decrease with increasing graphite content as compared to that of the base material.The wear rate and average coefficient of friction decrease with the addition of graphite and was found to be minimum at 5 wt.%graphite reinforcement.The addition of 5 wt.%graphite in the composite exhibits superior wear properties as compared to that of the matrix material and other compositions of the Mg-Gr composites.展开更多
Metal matrix composites （MMCs） as advanced materials, while producing the components with high dimensional accuracy and intricate shapes, are more complex and cost effective for machining than conventional alloys. I...Metal matrix composites （MMCs） as advanced materials, while producing the components with high dimensional accuracy and intricate shapes, are more complex and cost effective for machining than conventional alloys. It is due to the presence of discontinuously distributed hard ceramic with the MMCs and involvement of a large number of machining control variables. However, determination of optimal machining conditions helps the process engineer to make the process efficient and effec- tive. In the present investigation a novel hybrid multi-response optimization approach is proposed to derive the economic machining conditions for MMCs. This hybrid approach integrates the concepts of grey relational analysis （GRA）, principal component analysis （PCA） and Taguchi method （TM） to derive the optimal machining conditions. The machining experiments are planned to machine A17075/SiCp MMCs using wire-electrical discharge machining （WEDM） process. SiC particulate size and its weight percentage are explicitly considered here as the process variables along with the WEDM input variables. The derived optimal process responses are confirmed by the experimental validation tests and the results show satisfactory. The practical possibility of the derived optimal machining conditions is also analyzed and presented using scanning electron microscope （SEM） examinations. According to the growing industrial need of making high performance, low cost components, this investigation provides a simple and sequential approach to enhance the WEDM performance while machining MMCs.展开更多
Titanium metal matrix composite(Ti-MMC)has excellent features and capabilities which can be considered a potential candidate to replace commercial titanium and superalloys within an extensive range of products and ind...Titanium metal matrix composite(Ti-MMC)has excellent features and capabilities which can be considered a potential candidate to replace commercial titanium and superalloys within an extensive range of products and industrial sectors.Regardless of the superior features in Ti-MMC,however,referring to several factors including high unit cost and existence of rigid and abrasive ceramic particles in the generated matrices of the work part,the Ti-MMC is grouped as extremely difficult to cut with a poor level of machinability.Furthermore,adequate process parameters for machining Ti-MMCs under several lubrication methods are rarely studied.Therefore,adequate knowledge of this regard is strongly demanded.Among machinability attributes,ultrafine particles(UFPs)and fine particles(FPs)have been selected as the main machinability attributes and the factors leading to minimized emission have been studied.According to experimental observations,despite the type of coating used,the use of higher levels of flow rate led to less UFPs,while no significant effects were observed on UFPs.Under similar cutting conditions,higher levels of FPs were recorded under the use of uncoated inserts.Moreover,cutting speed had no significant influence on UFPs;nevertheless,it significantly affects the FPs despite the type of insert used.展开更多
The structural deterioration caused by the relatively weak out-of-plane bending stiffness and the chemically-active edge area of graphene limits its outperformance in strengthening for Al matrix composites(AMCs).Intro...The structural deterioration caused by the relatively weak out-of-plane bending stiffness and the chemically-active edge area of graphene limits its outperformance in strengthening for Al matrix composites(AMCs).Introducing one-dimensional(1D)carbon nanotubes(CNTs)to graphene/metal system is one of the promised strategies to complement the weakness of 2D graphene and make full use of the outstanding intrinsic properties of the both reinforcements.To date,such synergistic strengthening and toughening mechanisms are largely unknown.In this study,AMCs reinforced by a novel hybrid reinforcement,i.e.,graphene nanosheets decorated with Cu nanoparticles and CNTs(Cu@GNS-CNTs),are fabricated by an in-situ synthesis method.The combined contrast experiments validated that the organically integrated reinforcing structure promotes the intrinsic load bearing capacity of GNS and the strain hardening capability of the Al matrix simultaneously.As a result,the composites achieved excellent tensile strength and uniform elongation with almost no loss.The strengthening mechanism originated primarily from the hybrid reinforcement exhibits superior load-transfer,fracture inhibition and dislocation storage capability by controlling the interface reaction to construct an effective interface structure without damaging the reinforcement.Our work identifies a promising structural modification strategy for 2D materials and provides mechanistic insights into the synergistic strengthening effect of graphene/CNTs hybrid reinforcement.展开更多
This study shows that the mechanical strength of the composite of Fe matrix and titanium carbide(Ti C)ceramic particles is significantly enhanced with addition of molybdenum(Mo) atoms. Ti C reinforced Fe(Fe-0.2C-7Mn) ...This study shows that the mechanical strength of the composite of Fe matrix and titanium carbide(Ti C)ceramic particles is significantly enhanced with addition of molybdenum(Mo) atoms. Ti C reinforced Fe(Fe-0.2C-7Mn) composites with and without Mo were fabricated by a liquid pressing infiltration(LPI)process and the effect of Mo on interfacial properties of TiC–Fe composite was investigated using atomic probe tomography(APT) analysis, molecular dynamics(MD) simulations, first-principle density functional theory(DFT), and thermodynamic calculations. First, DFT calculations showed that total energies of the Mo-doped Ti C–Fe superlattices strongly depend on the position of Mo defects, and are minimized when the Mo atom is located at the TiC/Fe interface, supporting the probable formation of MoC-like interphase at the TiC/Fe interface region. Then, APT analysis confirmed the DFT predictions by finding that about6.5 wt.% Mo is incorporated in the Ti C–Fe(Mo) composite and that sub-micrometer thick(Ti,Mo)C interphase is indeed formed near the interface. The MD simulations show that Mo atoms migrate to the Mo-free TiC–Fe interface at elevated temperatures and the mechanical strength of the interface is considerably enhanced, which is in good agreement with experimental observations.展开更多
基金This work was supported by Department of Science and Technology,Government of India,under Grant No:RP02197.
文摘Magnesium alloy(AZ91D)composites reinforced with silicon carbide particle with different volume percentage were fabricated by two step stir casting process.The effect of changes in particle size and volume fraction of SiC particles on physical and mechanical properties of composites were evaluated under as cast and heat treated(T6)conditions.The experimental results were compared with the standard theoretical models.The results reveal that the mechanical properties of composites increased with increasing SiC particles and decrease with increasing particle size.Distribution of particles and fractured surface were studied through SEM and the presence of elements is revealed by EDS study.
基金the National Natural Science Foundation of China(Grant Nos.51771130,51531004,and 51422104)the Tianjin youth talent support program+1 种基金the Tianjin Natural Science Funds for Distinguished Young(Grant No.17JCJQJC44300)the Tianjin Science and Technology Support Project(Grant No.17ZXCLGX00060)。
文摘To synthesize graphene economically and efficiently,as well as to improve the interface bonding between graphene and metal and to recede the aggregation issue of graphene,in this work,an easy and scalable bottom-up strategy for the mass production of metal nanoparticles modified graphene nanoplates(GNPs)was proposed.Cu nanoparticles modified GNPs(Cu-GNPs)and Ni nanoparticles modified GNPs(Ni-GNPs)were fabricated through this method,and then compounded with Al via ball milling technique.The asobtained Ni-GNPs/Al composite showed simultaneously improved strength and toughness compared with unreinforced Al,while the Cu-GNPs/Al composite presented a greater strengthening effect.The microstructure and interface of the two composites were carefully characterized and investigated to reveal the difference.First principle study was also adopted to explore the binding energy of different interface structures.This study could provide new insights into the fabrication of GNPs and the control of interface in GNPs/Al composites.
文摘Some properties of the Fe-based P/M composites sintered and reinforced by infiltration with Cu-Sn alloy were described.It is shown that the hardness of the sintered material is 2.5 times lower,tensile strength is 1.7 times lower and the wear resistance is 2.5-3.3 times lower in comparison with those of the infiltrated material.The presence of pores on the friction surface of the sintered material affects the features of the wear process.Due to the specific morphology of copper in the infiltrated material,the phenomenon of selective mass transfer is observed and worn surfaces have a spongy-capillary texture.
基金supported by the National Natural Science Foundation of China (No. 51471177)the Youth Innovation PromotionAssociation CAS (No. 2016178)the Fundamental Research Funds for the Central Universities (No. N160205001)
文摘The mechanical and wear behavior of copper-tungsten disulfide（Cu/WS_2） composites fabricated by spark plasma sintering（SPS） and hot pressing（HP） was investigated, comparatively. Results indicated that the addition of lubricant WS_2 substantially reduced wear rate of the Cu matrix composites fabricated by SPS,and the optimum content of WS_2 is 20 wt% with regard to the wear behavior. However, it affected a little to the wear rate while dramatically decreased the friction coefficient of the composite fabricated by HP.This difference in friction behavior of the self-lubricating composites fabricated by the two techniques was closely related to their different mechanical properties. Severe interfacial reaction occurred during spark plasma sintering, leading to brittle phase formation at interface.
基金This work was financially supported by the Research&De-velopment Projects in Key Areas in Guangdong Province(No.2020B010186002)the National Natural Science Foundation of China(No.U2037601)the Open Fund of Large Instruments(No.202103150177).
文摘The thermal properties of Mg alloys require further optimization to encounter the increasingly severe heat dissipation demands of high-power densities and highly integrated electronic components.In this study,a novel strategy of reaction-tunable diffusion bonding(RDB)was applied to manipulate the inter-facial reaction in the multilayered Cu mesh/ZK61 Mg foil composites.The displacement of the punch was utilized to quantify the degree of reactive diffusion with adjustable,visible,and high flexibility.The inter-face was artificially manipulated to produce the fluid Mg-Zn eutectic liquid phase filling the interfacial gap at high temperature for a short time,followed by diffusion bonding at low temperature.The thermal conductivity of the composites first increased and then decreased,which was synthetically affected by the amelioration of metallurgical bonding and the moderately reactive consumption of Cu.The reinforcement Cu was converted from the Hasselman-Johnson model to the Rayleigh model,reflecting the optimization of the interfacial bonding quality.The composites with thermal conductivity and lightweight synergy were fabricated successfully.Therefore,RDB is a progressive technique,shedding lights on the innovative lightweight metal matrix composites with high thermal conductivities relevant to the 5G communications and new energy vehicle industries.
基金financially co-supported by the National Natural Science Foundation of China (Nos. 51235004 and 51375235)the Fundamental Research Funds for the Central Universities (Nos. NE2014103 and NZ2016107)
文摘Porous Cu-Sn-Ti alumina composites were fabricated by sintering Cu-Sn-Ti alloy powders, graphite particles, and alumina hollow particles agent. The effects of the pore structure and distribution on the composites strength were evaluated. Different pore distributions were modeled by using finite element analysis to investigate the tensile strength of the composites. Furthermore, a fractal analysis-based box-covering algorithm was used on the Cu-Sn-Ti alumina composites topology graphs to better investigate the pore structure and distribution. Results obtained show that different sizes and concentrations of alumina hollow particles could result in different porosities from20% to 50%. A larger pore size and a higher pore concentration reduce the strength, but provide more space for chip formation as a bonding material of a grinding wheel. The body-centered pore structure of the composites shows the highest stress under a tension load. The original composites topology graphs have been transformed to ordered distributed pore graphs based on the total pore area conservation. The information dimension magnitude difference between the original topology graphs and the ordered distributed circulars graphs is found to be linear with the Cu-Sn-Ti alumina composites strength. A larger difference renders a lower flexural strength, which indicates that uniform ordered distributed pores could benefit the composites strength.
基金Izabela B.Zgłobicka acknowledges the funding provided by National Science Center for providing financial support to project Metal Matrix Composites with natural filler(Grant No.2018/31/D/ST8/00890).The authors are grateful to Dr Matt P.Ashworth from the University of Texas at Austin(USA)for critically reading the manuscript and correcting the language.
文摘A novel metal matrix composites(MMC)with Mg matrix reinforced with natural filler in the form of Didymosphenia geminata frustules(algae with distinctive siliceous shells)are presented in this work.Pulse plasma sintering(PPS)was used to manufacture Mg-based composites with 1,5 and 10 vol.%ceramic filler.As a reference,pure Mg was sintered.The results show that the addition of 1 vol.%Didymosphenia geminata frustules to the Mg matrix increases its corrosion resistance by supporting passivation reactions,and do not affect the morphology of L929 fibroblasts.Addition of 5 vol.%the filler does not cause cytotoxic effects,but it supports microgalvanic reactions leading to the greater corrosion rate.Higher content than 5 vol.%the filler causes significant microgalvanic corrosion,as well as increases cytotoxicity due to the greater micro-galvanic effect of the composites containing 10 and 15 vol.%diatoms.The results of contact angle measurements show the hydrophilic character of the investigated materials,with slightly increase in numerical values with addition of amount of ceramic reinforcement.The addition of Didymosphenia geminata frustules causes changes in a thermo-elastic properties such as mean apparent value of coefficient of thermal expansion(CTE)and thermal conductivity(λ).The addition of siliceous reinforcement resulted in a linear decrease of CTE and reduction in thermal conductivity over the entire temperature range.With the increasing addition of Didymosphenia geminata frustules,an increase in strength with a decrease in compressive strain is observed.In all composites an increase in microhardness was attained.The results clearly indicate that filler in the form of Didymosphenia geminata frustules may significantly change the most important properties of pure Mg,indicating its wide potential in the application of Mg-based composites with a special focus on biomedical use.
基金supported by the NSFC Basic Science Cen-ter Program for“MultiscaleProblems inNonlinear Mechanics”(No.11988102)the NSFC(Nos.11790292,11972346 and 11672316)+2 种基金Ye Qisun Science Foundation of NSFC(No.U2141204)the Key Research Program of the Chinese Academy of Sciences(No.ZDRW-CN-2021-2-3)the Strategic Priority Research Program of the Chinese Academy of Sciences(Nos.XDB22040302 and XDB22040303).
文摘High-strength metallic foams have a wide range of applications in engineering as lightweight structural and energy-absorbing materials.However,it is challenging to obtain metallic foam with both good energy absorption performance and high strength.Here,we developed a novel metal matrix syntactic foam fabri-cated with AlCoCrFeNi_(2.1) eutectic high entropy alloy and alumina cenospheres that exhibits a remarkable combination of high strength and energy absorption performance under both quasi-static and dynamic compression.The porous structure of syntactic foam fully exploits the properties of the AlCoCrFeNi_(2.1) alloy matrix with a unique FCC/B2 dual-phase eutectic microstructure and thus yields exceptional per-formance.We discovered that this dual-phase microstructure not only provides high strength but also allows the pores to collapse in a progressive and diffusive way,which enables the formation of a high and smooth energy absorption platform.It is found that the heterogeneity between the two phases in the matrix can provide back stress strengthening,and it also induces multiple micro shear bands and microcracks as additional energy dissipation modes as the deformation proceeds.This unique mechanism ensures the strength of microstructures and makes them fracture promptly,which causes the balance of strengthening and softening on the macro scale.This work opens the avenue for developing advanced high-strength lightweight structural and energy-absorbing materials.
基金the financial supports from National Key R&D program of China(Grant Number2017YFB0703103)Guangdong Province Key Area R&D Program(Grant Number 2019B010942001)Heilongjiang Touyan Team。
文摘The 5.0 vol.%GNP/2024Al composites were prepared by accumulated shear deformation combined with heat treatment,i.e.the thermomechanical treatment(TMT).The results showed that homogeneous distributed GNPs that aligned along the plastic deformation direction were obtained by six-pass drawing in the solution heat treatment state.The introducing of high-density dislocations in Al matrix by multiple drawing resulted in enhanced nucleation of precipitates and subsequent uniform growth during ageing.Consequently,ultra-strength GNP/2024Al composites,with yield and ultimate tensile strength 482 and571 MPa,respectively,were achieved.The high strength was attributed to homogeneous dispersion of undamaged GNPs,fine and dispersed precipitations and work-hardening effect.This work demonstrated that TMT could act as a feasible strategy for preparing high-performance GNP/Al composites.
文摘The constant increase in power and heat flux densities encountered in electronic devices fuels a rising demand for lightweight heat sink materials with suitable thermal properties.In this study,discontinuous pitch-based carbon fiber reinforced aluminum matrix（Al-CF） composites with aluminum–silicon alloy（Al–Si） were fabricated through hot pressing.The small amount of Al–Si contributed to enhance the sintering process in order to achieve fully dense Al–CF composites.A thermal conductivity and CTE of 258 W/（m K） and 7.0 9 10-6/K in the in-plane direction of the carbon fibers were obtained for a（Al95 vol%＋ Al–Si5 vol%）-CF50 vol%composite.Carbon fiber provides the reducing of CTE while the conservation of thermal conductivity and weight of Al.The achieved CTEs satisfy the standard requirements for a heat sink material,which furthermore possess a specific thermal conductivity of 109 W cm3/（m K g）.This simple process allows the low-cost fabrication of Al–CF composite,which is applicable for a lightweight heat sink material.
基金financially supported by the National Natural Science Foundation of China (Nos.21905180 and 51873108)Shenzhen Science and Technology Planning Project (Nos. JCYJ20200109141640095 and JCYJ20170817110251498)Guangdong-Hong Kong-Macao Joint Laboratory (No. 2019B121205001)。
文摘The design of flexible composite electrodes has become the top priority in energy storage devices for the development of future wearable intelligent electronics.However,searching for fully integrated,ultrathin flexible composite electrodes with satisfying electrochemical performance is still a major challenge.Herein,we introduce a nanoporous gold metallic glass(MG) ribbon-based composite electrode with excellent electric conductivity,mechanical flexibility,and extra capacitance by integrating polypyrrole(PPy) into wrinkled nanoporous ribbon(NPG@MG).The freestanding,ultrathin,highly conductive and flexible" nature of the composite electrode prevents the conducting polymer from structural instability resulting from the volume swell and shrink during the charging/discharging circulation,and the packed PPy provides protection for the wrinkled topology on the surface of the MG ribbon.The capacitance of pure NPG@MG-PPy composite electrode reached 393 mF·cm^(-2).The ultra-thin all-solid-state flexible supercapacitor demonstrates an excellent capacitance of 172 mF·cM^(-2)(14.8 F·cm^(-3)),accompanied by a superior cycling capability after 8000 charge/discharge cycles attributed to mechanical flexibility.The areal energy density also reached 0.74 mWh·cm^(-3)(9μWh·cm^(-2)) at a power density of 1 μW·cm^(-2).This work provides valuable concepts on the design of PPy-based hybrid materials for flexible energy storage systems with greatly enhanced electrochemical performances.
基金The authors gratefully acknowledge University Malaysia Pahang (UMP) for providing financial support under project no RDU 160371 during this research work。
文摘In this research,the wear and mechanical responses of pure magnesium-graphite(Mg-Gr)composite have been investigated aiming to get the optimum composition of reinforcement.The composite materials were fabricated by mechanical alloying.The percentage of graphite reinforcement was chosen as 3,5,7 and 10 wt.%to identify its potential for self-lubricating property under dry sliding conditions.The mechanical properties including hardness,tensile strength and flexural strength of the composites and the base material were tested.The wear tests were conducted by using a pin-on-disc tribometer.The results show that the mechanical properties decrease with increasing graphite content as compared to that of the base material.The wear rate and average coefficient of friction decrease with the addition of graphite and was found to be minimum at 5 wt.%graphite reinforcement.The addition of 5 wt.%graphite in the composite exhibits superior wear properties as compared to that of the matrix material and other compositions of the Mg-Gr composites.
文摘Metal matrix composites （MMCs） as advanced materials, while producing the components with high dimensional accuracy and intricate shapes, are more complex and cost effective for machining than conventional alloys. It is due to the presence of discontinuously distributed hard ceramic with the MMCs and involvement of a large number of machining control variables. However, determination of optimal machining conditions helps the process engineer to make the process efficient and effec- tive. In the present investigation a novel hybrid multi-response optimization approach is proposed to derive the economic machining conditions for MMCs. This hybrid approach integrates the concepts of grey relational analysis （GRA）, principal component analysis （PCA） and Taguchi method （TM） to derive the optimal machining conditions. The machining experiments are planned to machine A17075/SiCp MMCs using wire-electrical discharge machining （WEDM） process. SiC particulate size and its weight percentage are explicitly considered here as the process variables along with the WEDM input variables. The derived optimal process responses are confirmed by the experimental validation tests and the results show satisfactory. The practical possibility of the derived optimal machining conditions is also analyzed and presented using scanning electron microscope （SEM） examinations. According to the growing industrial need of making high performance, low cost components, this investigation provides a simple and sequential approach to enhance the WEDM performance while machining MMCs.
基金financial support received from Fonds Québécois de la Recherche sur la Nature et les Technologies (FQRNT)
文摘Titanium metal matrix composite(Ti-MMC)has excellent features and capabilities which can be considered a potential candidate to replace commercial titanium and superalloys within an extensive range of products and industrial sectors.Regardless of the superior features in Ti-MMC,however,referring to several factors including high unit cost and existence of rigid and abrasive ceramic particles in the generated matrices of the work part,the Ti-MMC is grouped as extremely difficult to cut with a poor level of machinability.Furthermore,adequate process parameters for machining Ti-MMCs under several lubrication methods are rarely studied.Therefore,adequate knowledge of this regard is strongly demanded.Among machinability attributes,ultrafine particles(UFPs)and fine particles(FPs)have been selected as the main machinability attributes and the factors leading to minimized emission have been studied.According to experimental observations,despite the type of coating used,the use of higher levels of flow rate led to less UFPs,while no significant effects were observed on UFPs.Under similar cutting conditions,higher levels of FPs were recorded under the use of uncoated inserts.Moreover,cutting speed had no significant influence on UFPs;nevertheless,it significantly affects the FPs despite the type of insert used.
基金financially supported by the Chinese National Natural Science Fund for Distinguished Young Scholars(No.52025015)the National Natural Science Foundation of China(Nos.51771130,52071230,52101181)+3 种基金the Tianjin Youth Talent Support Program,the Tianjin Natural Science Funds for Distinguished Young Scholars(No.17JCJQJC44300)the Tianjin Science and Technology Support Project(No.17ZXCLGX00060)the China Postdoctoral Science Foundation(Nos.2020M670648 and 2021T140505)the Joint Fund of Ministry of Education for Equipment Pre-Research(No.6141A02033230)。
文摘The structural deterioration caused by the relatively weak out-of-plane bending stiffness and the chemically-active edge area of graphene limits its outperformance in strengthening for Al matrix composites(AMCs).Introducing one-dimensional(1D)carbon nanotubes(CNTs)to graphene/metal system is one of the promised strategies to complement the weakness of 2D graphene and make full use of the outstanding intrinsic properties of the both reinforcements.To date,such synergistic strengthening and toughening mechanisms are largely unknown.In this study,AMCs reinforced by a novel hybrid reinforcement,i.e.,graphene nanosheets decorated with Cu nanoparticles and CNTs(Cu@GNS-CNTs),are fabricated by an in-situ synthesis method.The combined contrast experiments validated that the organically integrated reinforcing structure promotes the intrinsic load bearing capacity of GNS and the strain hardening capability of the Al matrix simultaneously.As a result,the composites achieved excellent tensile strength and uniform elongation with almost no loss.The strengthening mechanism originated primarily from the hybrid reinforcement exhibits superior load-transfer,fracture inhibition and dislocation storage capability by controlling the interface reaction to construct an effective interface structure without damaging the reinforcement.Our work identifies a promising structural modification strategy for 2D materials and provides mechanistic insights into the synergistic strengthening effect of graphene/CNTs hybrid reinforcement.
基金financially supported by the Fundamental Research Program (PNK7480) of the Korea Institute of Materials Science (KIMS)the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) (NRF2020M3H4A3105943)+1 种基金supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF)funded by the Ministry of Education (NRF2014R1A1A2059123)。
文摘This study shows that the mechanical strength of the composite of Fe matrix and titanium carbide(Ti C)ceramic particles is significantly enhanced with addition of molybdenum(Mo) atoms. Ti C reinforced Fe(Fe-0.2C-7Mn) composites with and without Mo were fabricated by a liquid pressing infiltration(LPI)process and the effect of Mo on interfacial properties of TiC–Fe composite was investigated using atomic probe tomography(APT) analysis, molecular dynamics(MD) simulations, first-principle density functional theory(DFT), and thermodynamic calculations. First, DFT calculations showed that total energies of the Mo-doped Ti C–Fe superlattices strongly depend on the position of Mo defects, and are minimized when the Mo atom is located at the TiC/Fe interface, supporting the probable formation of MoC-like interphase at the TiC/Fe interface region. Then, APT analysis confirmed the DFT predictions by finding that about6.5 wt.% Mo is incorporated in the Ti C–Fe(Mo) composite and that sub-micrometer thick(Ti,Mo)C interphase is indeed formed near the interface. The MD simulations show that Mo atoms migrate to the Mo-free TiC–Fe interface at elevated temperatures and the mechanical strength of the interface is considerably enhanced, which is in good agreement with experimental observations.
