To achieve Ti/Mg bimetallic composite with high strength and metallurgical bonding interface,Al interlayer and Zn/Al composite interlayer were used to prepare TC4/AZ91D bimetal composite with metallurgical bonding int...To achieve Ti/Mg bimetallic composite with high strength and metallurgical bonding interface,Al interlayer and Zn/Al composite interlayer were used to prepare TC4/AZ91D bimetal composite with metallurgical bonding interface by solid-liquid compound casting,respectively.Al interlayer was prepared on the surface of TC4 alloy by hot dipping,and Zn/Al composite interlayer was prepared by electroplating process.The results suggested that the phases across the interface were Al Ti andα(Al)+Mg_(21)(Al,Zn)_(17)when Zn/Al composite interlayer was used.When Al interlayer was used as interlayer,Al Mg Ti ternary structure and Al_(12)Mg_(17)+δ-Mg eutectic structure were the main phases at the interface.The shear strength of TC4/AZ91D bimetal with Zn/Al composite interlayer was much higher than that with pure Al interlayer,and the value of the shear strength was increased from 48.5 to 67.4 MPa.Thermodynamic models based on different compositions of the interface were established to explain the microstructure evolution of the interfacial zone.展开更多
Porous Ti-Mg composites were successfully fabricated through powder metallurgy processing with ammonium hydrogen carbonate （NH4HCO3） as a space-holder. The effects of NH4HCO3 on properties of porous composites were ...Porous Ti-Mg composites were successfully fabricated through powder metallurgy processing with ammonium hydrogen carbonate （NH4HCO3） as a space-holder. The effects of NH4HCO3 on properties of porous composites were comprehensively investigated. The pore characteristics and compressive properties of the specimens were characterized by X-ray diffractometry （XRD） and scanning electron microscopy （SEM）. The results show that the porosity of the porous composites can be tailored effectively by changing the amount of NH4HCO3 added, and the use of NI-I4HCO3 has no influence on the microstructure and phase constituents of the Ti-10%Mg porous composites. The open porosity and compressive strength as well as compressive elastic modulus vary with the adding amount and particle size of NHaHCO3. When the mass fraction of NHaHCO3 added is 25%, elastic modulus and compressive strength of composites with porosity of around 50% are found to be similar to those of human bone.展开更多
以不同脱氧方式熔炼的海洋工程用钢为研究对象,利用SEM、EDS及Image-Pro Plus 6.0软件对钢中夹杂物形貌、组成及尺寸分布等进行表征,通过3.5%NaCl溶液中阳极极化及腐蚀实验对钢中夹杂物诱发点蚀的行为进行探究。结果表明,与Al-Mg脱氧钢...以不同脱氧方式熔炼的海洋工程用钢为研究对象,利用SEM、EDS及Image-Pro Plus 6.0软件对钢中夹杂物形貌、组成及尺寸分布等进行表征,通过3.5%NaCl溶液中阳极极化及腐蚀实验对钢中夹杂物诱发点蚀的行为进行探究。结果表明,与Al-Mg脱氧钢相比,Ti-Mg脱氧钢中形成了含有TiO_x的复合氧化物,夹杂数量更多且平均尺寸更小(小于1μm),有利于MnS的异质形核析出及弥散分布;低腐蚀活性的含TiOx复合氧化物及高度分散、异质局部析出MnS夹杂具有较低的点蚀敏感性及自腐蚀催化作用,降低了点蚀的诱发及扩展,有效提高了钢的抗点蚀性能。展开更多
In this study,HEA/AI composite interlayer was used to fabricate Ti/Mg bimetal composites by solidliquid compound casting process.The Al layer was prepared on the surface of TC4 alloy by hot dipping,and the FeCoNiCr HE...In this study,HEA/AI composite interlayer was used to fabricate Ti/Mg bimetal composites by solidliquid compound casting process.The Al layer was prepared on the surface of TC4 alloy by hot dipping,and the FeCoNiCr HEA layer was prepared by magnetron sputtering onto the Al layer.The influence of the HEA layer thickness and pouring temperature on interface evolution was investigated based on SEM observation and thermodynamic analysis.Results indicate that the sluggish diffusion effect of HEA can effectively inhibit the interfacial diffusion between Al and Mg,which is conducive to the formation of solid solution,especially when the thickness of HEA is 800 nm.With the increase of casting temperature from 720 ℃ to 730 ℃,740℃,and 750 ℃,α-Al(Mg),α-Al(Mg)+Al3Mg2,Al3Mg2+Al12Mg17,and Al12Mg17+δ-Mg are formed at the interface of Ti/Mg bimetal,respectively.When the thickness of the HEA layer is 800 nm and the pouring temperature is 720 ℃,the bonding strength of the Ti/Mg bimetal can reach the maximum of 93.6 MPa.展开更多
Ti/Mg laminated metal composites(LMCs)were processed by hot roll bonding and subsequent annealing at 200℃and300℃for 1 h,and the effect of dynamic recrystallization on the microstructure and anisotropy behavior was i...Ti/Mg laminated metal composites(LMCs)were processed by hot roll bonding and subsequent annealing at 200℃and300℃for 1 h,and the effect of dynamic recrystallization on the microstructure and anisotropy behavior was investigated in detail.The results revealed that,in both as-rolled and annealed Ti/Mg LMCs,the inhomogeneous distribution in the microstructure of Mg layers near the interface and near the center was related to the effect of friction between the roller and sheet surface and uncoordinated deformation between constituent layers.With increasing annealing temperature,Ti/Mg LMCs exhibited excellent elongation without sacrificing strength properties,which was mainly due to the improvement in bonding strength and the increasing strain gradient at the interface between soft and hard layers after annealing treatment.Besides,the increasing Schmid factors(SFs)of prismatic slip and pyramidal slip in Mg layers contributed to the improved plastic deformation ability of Ti/Mg LMCs.The experimental analysis indicated that the presence of Mg alloys resulted in the microstructure and mechanical properties of LMCs were different along various loading directions,and annealing treatment can effectively inhibit the anisotropic behavior of Ti/Mg LMCs resulting from the weakening of basal texture in the Mg layer.展开更多
The volume fractions and morphology of precipitates in precipitation-strengthened Cu-Ti alloys,which precipitate mainly as continuous and discontinuous precipitates,are important for the application of the alloy.This ...The volume fractions and morphology of precipitates in precipitation-strengthened Cu-Ti alloys,which precipitate mainly as continuous and discontinuous precipitates,are important for the application of the alloy.This study employed hardness and electrical conductivity tests transmission electron microscopy(TEM),atom probe tomography(APT),and first-principles calculations to demonstrate that the addition of Mg is effective for accelerating nanosized continuousβ'-Cu_(4)Ti precipitation as well as for suppressing the precipitation of coarse lamellar discontinuousβ-Cu_(4)Ti precipitates along the grain boundaries,resulting in Cu-Ti alloys with high yield strength and good electrical conductivity.The results showed that the continuous precipitation ofβ'-Cu_(4)Ti was accelerated by the Mg additions,which reduced the supersaturation of the matrix,thereby reducing the chemical driving force for the discontinuous precipitates.On the other hand,Mg additions increased the mismatch between the discontinuousβ-Cu_(4)Ti precipitates and matrix decreased the nucleation rate of the discontinuous precipitates,and increased the spacing of the discontinuous precipitation layer,resulting in a lower growth rate of the discontinuous precipitates.Therefore,the addition of Mg to Cu-Ti alloys enhances the strength and improves the resistance to over-ageing.展开更多
基金the financial support from the National Natural Science Foundation of China(No.51875062)。
文摘To achieve Ti/Mg bimetallic composite with high strength and metallurgical bonding interface,Al interlayer and Zn/Al composite interlayer were used to prepare TC4/AZ91D bimetal composite with metallurgical bonding interface by solid-liquid compound casting,respectively.Al interlayer was prepared on the surface of TC4 alloy by hot dipping,and Zn/Al composite interlayer was prepared by electroplating process.The results suggested that the phases across the interface were Al Ti andα(Al)+Mg_(21)(Al,Zn)_(17)when Zn/Al composite interlayer was used.When Al interlayer was used as interlayer,Al Mg Ti ternary structure and Al_(12)Mg_(17)+δ-Mg eutectic structure were the main phases at the interface.The shear strength of TC4/AZ91D bimetal with Zn/Al composite interlayer was much higher than that with pure Al interlayer,and the value of the shear strength was increased from 48.5 to 67.4 MPa.Thermodynamic models based on different compositions of the interface were established to explain the microstructure evolution of the interfacial zone.
文摘Porous Ti-Mg composites were successfully fabricated through powder metallurgy processing with ammonium hydrogen carbonate （NH4HCO3） as a space-holder. The effects of NH4HCO3 on properties of porous composites were comprehensively investigated. The pore characteristics and compressive properties of the specimens were characterized by X-ray diffractometry （XRD） and scanning electron microscopy （SEM）. The results show that the porosity of the porous composites can be tailored effectively by changing the amount of NH4HCO3 added, and the use of NI-I4HCO3 has no influence on the microstructure and phase constituents of the Ti-10%Mg porous composites. The open porosity and compressive strength as well as compressive elastic modulus vary with the adding amount and particle size of NHaHCO3. When the mass fraction of NHaHCO3 added is 25%, elastic modulus and compressive strength of composites with porosity of around 50% are found to be similar to those of human bone.
文摘以不同脱氧方式熔炼的海洋工程用钢为研究对象,利用SEM、EDS及Image-Pro Plus 6.0软件对钢中夹杂物形貌、组成及尺寸分布等进行表征,通过3.5%NaCl溶液中阳极极化及腐蚀实验对钢中夹杂物诱发点蚀的行为进行探究。结果表明,与Al-Mg脱氧钢相比,Ti-Mg脱氧钢中形成了含有TiO_x的复合氧化物,夹杂数量更多且平均尺寸更小(小于1μm),有利于MnS的异质形核析出及弥散分布;低腐蚀活性的含TiOx复合氧化物及高度分散、异质局部析出MnS夹杂具有较低的点蚀敏感性及自腐蚀催化作用,降低了点蚀的诱发及扩展,有效提高了钢的抗点蚀性能。
基金financial supports from the National Natural Science Foundation of China (No. 51875062)China Postdoctoral Science Foundation (No. 2021M700567)。
文摘In this study,HEA/AI composite interlayer was used to fabricate Ti/Mg bimetal composites by solidliquid compound casting process.The Al layer was prepared on the surface of TC4 alloy by hot dipping,and the FeCoNiCr HEA layer was prepared by magnetron sputtering onto the Al layer.The influence of the HEA layer thickness and pouring temperature on interface evolution was investigated based on SEM observation and thermodynamic analysis.Results indicate that the sluggish diffusion effect of HEA can effectively inhibit the interfacial diffusion between Al and Mg,which is conducive to the formation of solid solution,especially when the thickness of HEA is 800 nm.With the increase of casting temperature from 720 ℃ to 730 ℃,740℃,and 750 ℃,α-Al(Mg),α-Al(Mg)+Al3Mg2,Al3Mg2+Al12Mg17,and Al12Mg17+δ-Mg are formed at the interface of Ti/Mg bimetal,respectively.When the thickness of the HEA layer is 800 nm and the pouring temperature is 720 ℃,the bonding strength of the Ti/Mg bimetal can reach the maximum of 93.6 MPa.
基金financially supported by the Special fund for Special Posts of Guizhou University(No.[2022]06)the National Natural Science Foundation of China(No.52065009)the Science and Technology Planning Project of Guizhou Province in China(No.ZK[2021]269)。
文摘Ti/Mg laminated metal composites(LMCs)were processed by hot roll bonding and subsequent annealing at 200℃and300℃for 1 h,and the effect of dynamic recrystallization on the microstructure and anisotropy behavior was investigated in detail.The results revealed that,in both as-rolled and annealed Ti/Mg LMCs,the inhomogeneous distribution in the microstructure of Mg layers near the interface and near the center was related to the effect of friction between the roller and sheet surface and uncoordinated deformation between constituent layers.With increasing annealing temperature,Ti/Mg LMCs exhibited excellent elongation without sacrificing strength properties,which was mainly due to the improvement in bonding strength and the increasing strain gradient at the interface between soft and hard layers after annealing treatment.Besides,the increasing Schmid factors(SFs)of prismatic slip and pyramidal slip in Mg layers contributed to the improved plastic deformation ability of Ti/Mg LMCs.The experimental analysis indicated that the presence of Mg alloys resulted in the microstructure and mechanical properties of LMCs were different along various loading directions,and annealing treatment can effectively inhibit the anisotropic behavior of Ti/Mg LMCs resulting from the weakening of basal texture in the Mg layer.
基金financially supported by the Technological Innovation 2025&Major Special Project of Ningbo(Nos.2021Z084 and 2020Z039)。
文摘The volume fractions and morphology of precipitates in precipitation-strengthened Cu-Ti alloys,which precipitate mainly as continuous and discontinuous precipitates,are important for the application of the alloy.This study employed hardness and electrical conductivity tests transmission electron microscopy(TEM),atom probe tomography(APT),and first-principles calculations to demonstrate that the addition of Mg is effective for accelerating nanosized continuousβ'-Cu_(4)Ti precipitation as well as for suppressing the precipitation of coarse lamellar discontinuousβ-Cu_(4)Ti precipitates along the grain boundaries,resulting in Cu-Ti alloys with high yield strength and good electrical conductivity.The results showed that the continuous precipitation ofβ'-Cu_(4)Ti was accelerated by the Mg additions,which reduced the supersaturation of the matrix,thereby reducing the chemical driving force for the discontinuous precipitates.On the other hand,Mg additions increased the mismatch between the discontinuousβ-Cu_(4)Ti precipitates and matrix decreased the nucleation rate of the discontinuous precipitates,and increased the spacing of the discontinuous precipitation layer,resulting in a lower growth rate of the discontinuous precipitates.Therefore,the addition of Mg to Cu-Ti alloys enhances the strength and improves the resistance to over-ageing.
