TiAl有序金属间化合物超塑性变形的状态方程  

Phenomenological equation of superplastic deformation of TiAl intermatellics

作　　者：张俊红[1] 徐亚娟[1] 贺跃辉[2] 

机构地区：[1]洛阳理工学院材料科学与工程系,洛阳471023 [2]中南大学粉末冶金国家重点实验室,长沙410083

出　　处：《粉末冶金材料科学与工程》2013年第4期465-470,共6页Materials Science and Engineering of Powder Metallurgy

基　　金：国家高技术研究发展计划(863计划)资助项目(715-005-0040)

摘　　要：采用应变速率递增实验研究有序金属间化合物Ti-48Al-2.3Cr-0.2Mo（原子分数,%）在800~1 100℃范围内的超塑性变形力学行为,在实验观察的基础上,对超塑性变形的状态方程进行分析。结果表明,在800~900℃和950~1 100℃区间,合金的应力、应变速率、温度、晶粒尺寸间的关系发生改变,在800~900℃区间,应变速率敏感性因子m的最佳值在0.52~0.67之间,表观激活能为Qapp=178 kJ/mol,为晶界扩散激活能,晶粒尺寸因子P=3;在950~1 100℃区间,m的最佳值为0.63~0.77,Qapp=290 kJ/mol,为体积扩散激活能,P=2。经实验拟合,得到TiAl合金超塑性变形的经验状态方程：在800~900℃区间,5.47×107×（σ/E）2（bDgb/d3）;在950~1 100℃区间,1.29×108×（σ/E）2（DL/d2）,与O D Sherby等在无序合金中观察到的现象相符,其超塑性变形的动力学因子仅比无序合金的动力学因子小约1个数量级,说明有序合金的结构有序性对超塑性变形速率影响不大。Superplastic mechanical behavior of Ti-48Al-2.3Cr-0.2Mo（at%） alloy was investigated at temperatures in the range of 800~1 100 ℃ with strain ratesin 5 10 5~1 10 3s 1by incremental strain rate tests.Depending on the data obtained,the phenomenological equation of the superplastic flow was discussed.It is revealed that the deformation exhibit another specific stress,temperature,and grain-sized dependences when temperature in the range of 800~900 ℃ and 950~1 100 ℃.When tested at 800~900 ℃,the maximum strain rate sensitivity（m） values are 0.52~0.67,the activation energy is calculated as Qapp =178 kJ/mol,which associated with that for grain boundary diffusion,the grain size exponent,p,is equal to 3.When tested at 950~1 100 ℃,thebest strain rate sensitivity（m） values are 0.63~0.77,the activation energy is calculated as Qapp =290 kJ/mol,which associated with that for lattice diffusion,the grain size exponent,p,is equal to 2.The equation of the superplastic deformation can be represented by 5.47×107×（σ/E）2（bDgb /d3）,at 800 900 ℃ and 1.29×108×（σ/E）2（DL /d2）,at 950 1 100 ℃,which is similar to that in disordered superplastic materials observed by O D Sherby et al,only with the kinetics in the ordered TiAl alloy is 1 order of magnitude smaller than that in disordered alloys,which suggests that,the ordered structure in TiAl alloy,which have dislocation barriers in dislocation plasticity,do not affect the kinetics of superplastic deformation heavily.

关 键 词：TIAL基合金 超塑性 激活能 状态方程 

分 类 号：TG146.2[一般工业技术—材料科学与工程]