An innovative processing route was adopted to fabricate 42.1%(volume fraction) TiC/AZ91D magnesium matrix composites. The reinforcement TiC was in situ synthesized from elemental powders of Ti and C and the matrix mag...An innovative processing route was adopted to fabricate 42.1%(volume fraction) TiC/AZ91D magnesium matrix composites. The reinforcement TiC was in situ synthesized from elemental powders of Ti and C and the matrix magnesium alloy AZ91D pressurelessly infiltrated into the preform of Ti and C. A comparative tensile deformation tests were conducted on the as-synthesized TiC/AZ91D composites and magnesium alloy AZ91D. The true strain—stress curves were fitted by Hollomon relation and their failure mechanisms were finally analyzed. The results show that the in situ formed TiC can increase the tensile strength, and is especially effective at elevated temperatures. Theoretical calculation of the strain hardening exponent (n) for TiC/AZ91D composites indicates that the n value ranges from 0.71 to 0.82 when tensile deformation was carried out at 423?723 K and shows fracture with brittle characteristic. However, the n value of 0.11?0.32 obtained for the matrix alloy AZ91D shows typical ductile features at elevated temperatures.展开更多
采用真空热压-内氧化烧结法制备TiC体积分数分别为0、10 vol%、20 vol%的TiC/Cu-Al2O3复合材料,观察和分析了其显微组织、测试和分析了其性能;利用Gleeble-1500D热力模拟试验机,研究了3种复合材料在变形温度为450-850℃,应变速率为0.001...采用真空热压-内氧化烧结法制备TiC体积分数分别为0、10 vol%、20 vol%的TiC/Cu-Al2O3复合材料,观察和分析了其显微组织、测试和分析了其性能;利用Gleeble-1500D热力模拟试验机,研究了3种复合材料在变形温度为450-850℃,应变速率为0.001-1 s^-1条件下的热变形行为。结果表明,复合材料的相对密度在97.1%以上,随着TiC含量的增加,其导电率下降、硬度升高。TiC/Cu-Al2O3复合材料的真应力-真应变曲线主要以动态再结晶机制为特征,峰值应力随变形温度的降低或应变速率的升高而增加;高温变形条件下TiC/Cu-Al2O3复合材料流变应力本构方程可以用双曲线正弦方程和Z参数描述;其热变形激活能分别为163.939 k J/mol（0 vol%TiC）、164.142 k J/mol（10 vol%TiC）和210.762 k J/mol（20 vol%TiC）。展开更多
Hot compression behavior of TiC–Al2O3/Al composites was studied using the Gleeble-1500 system at a temperature range of 300–550 °C and at strain rate range of 0.01–10.00 s-1. The associated structural changes ...Hot compression behavior of TiC–Al2O3/Al composites was studied using the Gleeble-1500 system at a temperature range of 300–550 °C and at strain rate range of 0.01–10.00 s-1. The associated structural changes were studied by TEM observations. The results show that stress level decreases with deformation temperature increasing and strain rate decreasing, which can be represented by a Zener–Hollomon parameter in an exponent-type equation with hot deformation activation energy Q of 172.56 kJ·mol-1.Dynamic recovery occurs easily when strain rates are less than 10.00 s-1. Dynamic recrystallization can occur at strain rate of 10.00 s-1.展开更多
Thermal compression testing was investigated using the Gleeble 3800 thermal simulator,and thermal deformation behavior of particle-reinforced titanium matrix composites(TMCs)was studied under deformation temperatures ...Thermal compression testing was investigated using the Gleeble 3800 thermal simulator,and thermal deformation behavior of particle-reinforced titanium matrix composites(TMCs)was studied under deformation temperatures of 750-900°C,strain rates of 0.001-1 s^(-1),and experimental deformation of 60%.According to obtained flow stress curves,the hot deformation characteristics were analyzed.Based on the Arrhenius hyperbolic sinusoidal model,the constitutive equation at high temperature was established.Based on the theory of dynamic material models,a hot processing map of TMCs at high temperature was established,and the peak region of power dissipation rate and the instability region in the hot processing map were both determined.At the same time,the corresponding microstructures in the peak power dissipation rate and rheological instability regions were observed.The results showed that flow stress decreased with increasing deformation temperature and increased with increasing strain rate.The thermal deformation activation energy of titanium matrix composites was 301.8 kJ/mol.The Ti-6Al-4V/(TiB+TiC)composites possessed only one instability zone under high-temperature compression at a strain of 0.5,with corresponding temperatures at 750-840°C and strain rates at 0.1-1 s^(-1).The optimal thermal deformation parameters included corresponding temperatures of 830-880°C and strain rates of 0.001-0.05 s^(-1).The microstructures corresponding to optimal hot working parameters in processing maps were more homogeneous than the microstructures in the instability zone,including the distribution uniformity of reinforcement and the degree of dynamic recrystallization,and no instability phenomena including abnormal grain growth,microcracks or intensive fracture of reinforcements were found,indicating that the hot processing map had a positive guiding effect on the option of desirable material thermal-working parameters.展开更多
基金Project(20032012) supported by the Natural Science Foundation of Liaoning Province, China
文摘An innovative processing route was adopted to fabricate 42.1%(volume fraction) TiC/AZ91D magnesium matrix composites. The reinforcement TiC was in situ synthesized from elemental powders of Ti and C and the matrix magnesium alloy AZ91D pressurelessly infiltrated into the preform of Ti and C. A comparative tensile deformation tests were conducted on the as-synthesized TiC/AZ91D composites and magnesium alloy AZ91D. The true strain—stress curves were fitted by Hollomon relation and their failure mechanisms were finally analyzed. The results show that the in situ formed TiC can increase the tensile strength, and is especially effective at elevated temperatures. Theoretical calculation of the strain hardening exponent (n) for TiC/AZ91D composites indicates that the n value ranges from 0.71 to 0.82 when tensile deformation was carried out at 423?723 K and shows fracture with brittle characteristic. However, the n value of 0.11?0.32 obtained for the matrix alloy AZ91D shows typical ductile features at elevated temperatures.
文摘采用真空热压-内氧化烧结法制备TiC体积分数分别为0、10 vol%、20 vol%的TiC/Cu-Al2O3复合材料,观察和分析了其显微组织、测试和分析了其性能;利用Gleeble-1500D热力模拟试验机,研究了3种复合材料在变形温度为450-850℃,应变速率为0.001-1 s^-1条件下的热变形行为。结果表明,复合材料的相对密度在97.1%以上,随着TiC含量的增加,其导电率下降、硬度升高。TiC/Cu-Al2O3复合材料的真应力-真应变曲线主要以动态再结晶机制为特征,峰值应力随变形温度的降低或应变速率的升高而增加;高温变形条件下TiC/Cu-Al2O3复合材料流变应力本构方程可以用双曲线正弦方程和Z参数描述;其热变形激活能分别为163.939 k J/mol（0 vol%TiC）、164.142 k J/mol（10 vol%TiC）和210.762 k J/mol（20 vol%TiC）。
基金financially supported by the Inner Mongolia Science and Technology Reward Foundation(No.20101707)the Inner Mongolia Natural Science Foundation(No.2013MS0804)+1 种基金the Inner Mongolia High School Scientific Research Foundation(No.NJZZ14056)the Inner Mongolia University of Technology Foundation(No.ZD20120015)
文摘Hot compression behavior of TiC–Al2O3/Al composites was studied using the Gleeble-1500 system at a temperature range of 300–550 °C and at strain rate range of 0.01–10.00 s-1. The associated structural changes were studied by TEM observations. The results show that stress level decreases with deformation temperature increasing and strain rate decreasing, which can be represented by a Zener–Hollomon parameter in an exponent-type equation with hot deformation activation energy Q of 172.56 kJ·mol-1.Dynamic recovery occurs easily when strain rates are less than 10.00 s-1. Dynamic recrystallization can occur at strain rate of 10.00 s-1.
基金This work was financially supported by the General project of Education Department of Liaoning Province(No.LQGD2019001)the Natural Science Foundation of China(No.51805335)。
文摘Thermal compression testing was investigated using the Gleeble 3800 thermal simulator,and thermal deformation behavior of particle-reinforced titanium matrix composites(TMCs)was studied under deformation temperatures of 750-900°C,strain rates of 0.001-1 s^(-1),and experimental deformation of 60%.According to obtained flow stress curves,the hot deformation characteristics were analyzed.Based on the Arrhenius hyperbolic sinusoidal model,the constitutive equation at high temperature was established.Based on the theory of dynamic material models,a hot processing map of TMCs at high temperature was established,and the peak region of power dissipation rate and the instability region in the hot processing map were both determined.At the same time,the corresponding microstructures in the peak power dissipation rate and rheological instability regions were observed.The results showed that flow stress decreased with increasing deformation temperature and increased with increasing strain rate.The thermal deformation activation energy of titanium matrix composites was 301.8 kJ/mol.The Ti-6Al-4V/(TiB+TiC)composites possessed only one instability zone under high-temperature compression at a strain of 0.5,with corresponding temperatures at 750-840°C and strain rates at 0.1-1 s^(-1).The optimal thermal deformation parameters included corresponding temperatures of 830-880°C and strain rates of 0.001-0.05 s^(-1).The microstructures corresponding to optimal hot working parameters in processing maps were more homogeneous than the microstructures in the instability zone,including the distribution uniformity of reinforcement and the degree of dynamic recrystallization,and no instability phenomena including abnormal grain growth,microcracks or intensive fracture of reinforcements were found,indicating that the hot processing map had a positive guiding effect on the option of desirable material thermal-working parameters.
