The concept of high entropy alloys(HEAs) or multi-principal component alloys has inspired a great progress of physical metallurgy along with several unusual phenomena. The high corrosion resistance of HEAs was frequen...The concept of high entropy alloys(HEAs) or multi-principal component alloys has inspired a great progress of physical metallurgy along with several unusual phenomena. The high corrosion resistance of HEAs was frequently mentioned but without convincing explanations. In this paper, the intrinsic mechanism of corrosion resistance in FCC HEAs was revealed by designing equal atomic alloys with single solid solution phase. The results showed that the Cr element in FCC HEAs played the dominant role in the corrosion resistance rather than the simple structure from high entropy effect or uniform element distribution.展开更多
The microstructural modification for cellular structures can achieve the improvement of dynamic me-chanical properties of a selective laser melted FeCoNiCrMo_(0.2)high-entropy alloy(SLM-FeCoNiCrMo_(0.2)HEA)and can exp...The microstructural modification for cellular structures can achieve the improvement of dynamic me-chanical properties of a selective laser melted FeCoNiCrMo_(0.2)high-entropy alloy(SLM-FeCoNiCrMo_(0.2)HEA)and can expand its promising applications in the field of high-velocity deformation.In this work,FeCoNiCrMo_(0.2)HEAs with cellular structures in different sizes were produced by selective laser melt-ing(SLM)with different process parameters.The dynamic mechanical properties and microstructure of the SLM-FeCoNiCrMo_(0.2)HEA were studied.The dynamic mechanical properties of the SLM-FeCoNiCrMo_(0.2)HEA increased with decrease of average size of cellular structures,and the values of them were sensitive to strain rates.The energy absorption,compressive strength and yield strength of the SLM-FeCoNiCrMo_(0.2)HEAs reached 315.6 MJ/m^(3),2.2 GPa and 775.6 MPa,respectively at a strain rate of 2,420 s^(−1),under the process parameters of laser power and scanning speed of 330 W and 800 mm/s,respectively,where the corresponding average size of cellular structures in the HEAs was 483.6 nm.The value of strain-hardening rate of the SLM-FeCoNiCrMo_(0.2)HEA was about 5.1 GPa at a strain level of 0.1,which was much higher than that of the powder-metallurgy FeCoNiCrMo_(0.2)HEA.The cellular structure was formed inside the molten pool with segregation of Mo on the boundary.Deformation localization appeared in the cellular structures,forming several deformation bands after high strain-rate deformation.The elemental segre-gation strengthening and dislocation strengthening are considered to be the main strengthening mecha-nisms in SLM-FeCoNiCrMo_(0.2)HEA.展开更多
Plasma cladding was used to prepare a CoCrFeMnNi high-entropy alloy(HEA)coating under different conditions.The process parameters were optimized using an orthogonal experiment design based on surface morphology qualit...Plasma cladding was used to prepare a CoCrFeMnNi high-entropy alloy(HEA)coating under different conditions.The process parameters were optimized using an orthogonal experiment design based on surface morphology quality characteristics,dilution rate,and hardness.The optimal process parameters were determined through range and variance analysis to be a cladding current of 70 A,a cladding speed of 7 cm·min^(-1),and a powder gas flow rate of 8 L·s^(-1).During the optimized experiments,both the cladded and annealed CoCrFeMnNi HEA coatings exhibit some pores,micro-voids,and a small amount of aggregation.However,the aggregation in the annealed coating is more dispersed than that in the cladded coating.The cladded CoCrFeMnNi HEA coating consists of simple FCC phases,while a new Cr-rich phase precipitates from the FCC matrix after annealing the coating at a temperature range of 550°C-950°C.After annealing at 850°C,the proportion of the FCC phase decreases compared to the cladded coating,and the number of large-angle grain boundaries is significantly reduced.However,the proportion of grains with sizes below 50μm increases from 61.7%to 74.3%.The micro-hardness and wear resistance of the cladded coating initially increases but then decreases with an increase in annealing temperature,indicating that appropriate annealing can significantly improve the mechanical properties of the CoCrFeMnNi HEA coatings by plasma cladding.The micro-hardness of the CoCrFeMnNi HEA coatings after annealing at 650°C increases to 274.82 HV_(0.2),while the friction coefficient decreases to below 0.595.展开更多
Eutectic and near-eutectic high entropy alloys （HEAs） have recently attracted a great deal of interest because of their promising properties, such as an excellent castability and unique combination of good ductility...Eutectic and near-eutectic high entropy alloys （HEAs） have recently attracted a great deal of interest because of their promising properties, such as an excellent castability and unique combination of good ductility and high strength. However, in the absence of a phase diagram, it remains a non-trivial task to find a eutectic or near-eutectic composition for a HEA system, which usually demands a tremendous amount of efforts if a trial-and-error approach is followed. In this paper, we briefly review the thermodynamics that governs the entectic solidification in regular binary and ternary alloys, and proceed to the discussion for the design of eutectic HEAs. Based on the data reported, we then propose an improved strategy which may enable an efficient search for the eutectic or near eutectic HEA compositions.展开更多
Fatigue failures cost approximately 4% of the United States' gross domestic product(GDP). The design of highly fatigue-resistant materials is always in demand. Different from conventional strategies of alloy desig...Fatigue failures cost approximately 4% of the United States' gross domestic product(GDP). The design of highly fatigue-resistant materials is always in demand. Different from conventional strategies of alloy design, high-entropy alloys(HEAs) are defined as materials with five or more principal elements, which could be solid solutions. This locally-disordered structure is expected to lead to unique fatigue-resistant properties. In this review, the studies of the fatigue behavior of HEAs during the last five years are summarized. The four-point-bending high-cycle fatigue coupled with statistical modelling, and the fatigue-crack-growth behavior of HEAs, are reviewed. The effects of sample defects and nanotwins-deformation mechanisms on four-point-bending high-cycle fatigue of HEAs are discussed in detail. The influence of stress ratio and temperature on fatigue-crack-growth characteristics of HEAs is also discussed. HEAs could exhibit comparable or greater fatigue properties, relative to conventional materials. Finally,the possible future work regarding the fatigue behavior of HEAs is suggested.展开更多
Objective To understand the genetic load in the Chinese population for improvement in diagnosis, prevention and rehabilitation of deafness. Methods DNA samples, immortalized cell lines as well as detailed clinical and...Objective To understand the genetic load in the Chinese population for improvement in diagnosis, prevention and rehabilitation of deafness. Methods DNA samples, immortalized cell lines as well as detailed clinical and audiometric data were collected through a national genetic resources collecting network. Two conventional genetic approaches were used in the studies. Linkage analysis in X chromosome and autosomes with microsatellite markers were performed in large families for gene mapping and positional cloning of novel genes. Candidate gene approach was used for screening the mtDNA 12SrRNA, GJB2 and SLC26A4 mutations in population -based samples. Results A total of 2,572 Chinese hearing loss families or sporadic cases were characterized in the reported studies, including seven X-linked, one Y-linked, 28 large and multiplex autosomal dominant hearing loss families, 607 simplex autosomal recessive hereditary hearing loss families, 100 mitochondrial inheritance families, 147 GJB2 induced hearing loss cases, 230 cases with enlarged vestibular aqueduct (EVA) syndrome, 169 sporadic cases with auditory neuropathy, and 1,283 sporadic sensorineural hearing loss cases. Through linkage analysis or sequence analysis, two X-linked families were found transmitting two novel mutations in the POU3F4 gene, while another X -linked family was mapped onto a novel locus, nominated as AUNX1 (auditory neuropathy, X-linked locus 1). The only Y-linked family was mapped onto the DFNY1 locus(Y-linked locus 1, DFNY1). Eight of the 28 autosomal dominant families were linked to various autosomal loci. In population genetics studies, 2,567 familial cases and sporadic patients were subjected to mutation screening for three common hearing loss genes: mtDNA 12S rRNA 1555G, GJB2 and SLC26A4. The auditory neuropathy cases in our samples were screened for OTOF gene mutations. Conclusions These data show that the Chinese population has a genetic load on hereditary hearing loss. Establishing personalized surveillance and prevention models for hearing展开更多
基金supported by National Natural Science Foundation of China(Grant No.5147113)
文摘The concept of high entropy alloys(HEAs) or multi-principal component alloys has inspired a great progress of physical metallurgy along with several unusual phenomena. The high corrosion resistance of HEAs was frequently mentioned but without convincing explanations. In this paper, the intrinsic mechanism of corrosion resistance in FCC HEAs was revealed by designing equal atomic alloys with single solid solution phase. The results showed that the Cr element in FCC HEAs played the dominant role in the corrosion resistance rather than the simple structure from high entropy effect or uniform element distribution.
基金The present work was financially supported by the National Natural Science of China(No.52020105013)by the State Key Laboratory of Powder Metallurgy(No.62102172).
文摘The microstructural modification for cellular structures can achieve the improvement of dynamic me-chanical properties of a selective laser melted FeCoNiCrMo_(0.2)high-entropy alloy(SLM-FeCoNiCrMo_(0.2)HEA)and can expand its promising applications in the field of high-velocity deformation.In this work,FeCoNiCrMo_(0.2)HEAs with cellular structures in different sizes were produced by selective laser melt-ing(SLM)with different process parameters.The dynamic mechanical properties and microstructure of the SLM-FeCoNiCrMo_(0.2)HEA were studied.The dynamic mechanical properties of the SLM-FeCoNiCrMo_(0.2)HEA increased with decrease of average size of cellular structures,and the values of them were sensitive to strain rates.The energy absorption,compressive strength and yield strength of the SLM-FeCoNiCrMo_(0.2)HEAs reached 315.6 MJ/m^(3),2.2 GPa and 775.6 MPa,respectively at a strain rate of 2,420 s^(−1),under the process parameters of laser power and scanning speed of 330 W and 800 mm/s,respectively,where the corresponding average size of cellular structures in the HEAs was 483.6 nm.The value of strain-hardening rate of the SLM-FeCoNiCrMo_(0.2)HEA was about 5.1 GPa at a strain level of 0.1,which was much higher than that of the powder-metallurgy FeCoNiCrMo_(0.2)HEA.The cellular structure was formed inside the molten pool with segregation of Mo on the boundary.Deformation localization appeared in the cellular structures,forming several deformation bands after high strain-rate deformation.The elemental segre-gation strengthening and dislocation strengthening are considered to be the main strengthening mecha-nisms in SLM-FeCoNiCrMo_(0.2)HEA.
基金This work was financially supported by the National Natural Science Foundation of China(No.51861025)the Jiangxi Provincial Department of Science and Technology(No.20203BDH80W008).
文摘Plasma cladding was used to prepare a CoCrFeMnNi high-entropy alloy(HEA)coating under different conditions.The process parameters were optimized using an orthogonal experiment design based on surface morphology quality characteristics,dilution rate,and hardness.The optimal process parameters were determined through range and variance analysis to be a cladding current of 70 A,a cladding speed of 7 cm·min^(-1),and a powder gas flow rate of 8 L·s^(-1).During the optimized experiments,both the cladded and annealed CoCrFeMnNi HEA coatings exhibit some pores,micro-voids,and a small amount of aggregation.However,the aggregation in the annealed coating is more dispersed than that in the cladded coating.The cladded CoCrFeMnNi HEA coating consists of simple FCC phases,while a new Cr-rich phase precipitates from the FCC matrix after annealing the coating at a temperature range of 550°C-950°C.After annealing at 850°C,the proportion of the FCC phase decreases compared to the cladded coating,and the number of large-angle grain boundaries is significantly reduced.However,the proportion of grains with sizes below 50μm increases from 61.7%to 74.3%.The micro-hardness and wear resistance of the cladded coating initially increases but then decreases with an increase in annealing temperature,indicating that appropriate annealing can significantly improve the mechanical properties of the CoCrFeMnNi HEA coatings by plasma cladding.The micro-hardness of the CoCrFeMnNi HEA coatings after annealing at 650°C increases to 274.82 HV_(0.2),while the friction coefficient decreases to below 0.595.
基金National Natural Science Foundation of China(51774179)Natural Science Foundation of Liaoning Province(20180550546)Joint Fund of State Key Laboratory of Metal Material for Marine Equipment and Application(HGSKL-USTLN(2021)03)。
基金supported by the City University of Hong Kong through the UGC Block Grant with the Project(Grant No.9610366)
文摘Eutectic and near-eutectic high entropy alloys （HEAs） have recently attracted a great deal of interest because of their promising properties, such as an excellent castability and unique combination of good ductility and high strength. However, in the absence of a phase diagram, it remains a non-trivial task to find a eutectic or near-eutectic composition for a HEA system, which usually demands a tremendous amount of efforts if a trial-and-error approach is followed. In this paper, we briefly review the thermodynamics that governs the entectic solidification in regular binary and ternary alloys, and proceed to the discussion for the design of eutectic HEAs. Based on the data reported, we then propose an improved strategy which may enable an efficient search for the eutectic or near eutectic HEA compositions.
基金supported by the Department of Energy(DOE),Office of Fossil Energy,National Energy Technology Laboratory(Grant No.DE-FE-0024054,DE-FE-0011194)the U.S.Army Research Office Project(Grant No.W911NF-13-1-0438)+4 种基金the National Science Foundation(DMR-1611180)the QuesTek Innovation LLC(limited liability company)the Ministry of Science and Technology of Taiwan(Grant No.MOST105-2221-E-007-017-MY3)the Department of Materials Science and Engineering at the National Tsing Hua University(Taiwan)the School of Materials Science and Engineering of the Dalian University of Technology,China
文摘Fatigue failures cost approximately 4% of the United States' gross domestic product(GDP). The design of highly fatigue-resistant materials is always in demand. Different from conventional strategies of alloy design, high-entropy alloys(HEAs) are defined as materials with five or more principal elements, which could be solid solutions. This locally-disordered structure is expected to lead to unique fatigue-resistant properties. In this review, the studies of the fatigue behavior of HEAs during the last five years are summarized. The four-point-bending high-cycle fatigue coupled with statistical modelling, and the fatigue-crack-growth behavior of HEAs, are reviewed. The effects of sample defects and nanotwins-deformation mechanisms on four-point-bending high-cycle fatigue of HEAs are discussed in detail. The influence of stress ratio and temperature on fatigue-crack-growth characteristics of HEAs is also discussed. HEAs could exhibit comparable or greater fatigue properties, relative to conventional materials. Finally,the possible future work regarding the fatigue behavior of HEAs is suggested.
基金supported by grants from the National High Tech Development Project (No. 2006AA028 Z181)the National Natural Science Foundation of China,Key Project (No. 30830104)+5 种基金the National Natural Science Foundation of China(No. 30771857, 30672310 & 30771203)the Foundation of National Excellent Doctoral Thesis (No. 200463)Beijing Nature Science Technology Major Project (No. D0906005 040291 & 7070002)the National 973 Project (No. 2007CB 507400)as well as the National Eleventh Scientific Program (No. 2006BAI02B06& 2007BAI18B12)the Sun Yat-Sen University Start-up Fund (Grant No. 3171310)
文摘Objective To understand the genetic load in the Chinese population for improvement in diagnosis, prevention and rehabilitation of deafness. Methods DNA samples, immortalized cell lines as well as detailed clinical and audiometric data were collected through a national genetic resources collecting network. Two conventional genetic approaches were used in the studies. Linkage analysis in X chromosome and autosomes with microsatellite markers were performed in large families for gene mapping and positional cloning of novel genes. Candidate gene approach was used for screening the mtDNA 12SrRNA, GJB2 and SLC26A4 mutations in population -based samples. Results A total of 2,572 Chinese hearing loss families or sporadic cases were characterized in the reported studies, including seven X-linked, one Y-linked, 28 large and multiplex autosomal dominant hearing loss families, 607 simplex autosomal recessive hereditary hearing loss families, 100 mitochondrial inheritance families, 147 GJB2 induced hearing loss cases, 230 cases with enlarged vestibular aqueduct (EVA) syndrome, 169 sporadic cases with auditory neuropathy, and 1,283 sporadic sensorineural hearing loss cases. Through linkage analysis or sequence analysis, two X-linked families were found transmitting two novel mutations in the POU3F4 gene, while another X -linked family was mapped onto a novel locus, nominated as AUNX1 (auditory neuropathy, X-linked locus 1). The only Y-linked family was mapped onto the DFNY1 locus(Y-linked locus 1, DFNY1). Eight of the 28 autosomal dominant families were linked to various autosomal loci. In population genetics studies, 2,567 familial cases and sporadic patients were subjected to mutation screening for three common hearing loss genes: mtDNA 12S rRNA 1555G, GJB2 and SLC26A4. The auditory neuropathy cases in our samples were screened for OTOF gene mutations. Conclusions These data show that the Chinese population has a genetic load on hereditary hearing loss. Establishing personalized surveillance and prevention models for hearing
