轧制变形量对Ti-45Al-7Nb-0.3W合金组织与性能的影响

利用X衍射分析(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、室温拉伸试验等手段,研究粉末冶金Ti-45Al-7Nb-0.3W(原子分数,%)合金包套轧制过程中的显微组织和力学性能的变化规律。结果表明:热等静压法态的Ti-45Al-7Nb-0.3W合金组织为近γ组织,主要由块状的γ相组成,同时包括少量的α2相及极少量的B2相。轧制后Ti Al合金板材为双态组织,B2相消失。随轧制变形量增加,合金板材强度增加,变形量为40%时,板材抗拉强度最大,达到955 MPa。继续增加变形量合金板材的力学性能有所降低。当变形量较小时,合金的塑性变形主要通过位错滑移和攀移来实现。随变形量增加,孪生和动态再结晶机制发挥作用。

Effect of rolling deformation on microstructure and mechanical property of Ti-45Al-7Nb-0.3W alloy

The microstructure and mechanical properties of powder metallurgy Ti-45Al-7Nb-0.3W (mole fraction, %) alloy during pack-rolling were studied by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and tensile tests. The results show that the initial microstructure of HIPed Ti-45Al-7Nb-0.3W alloy is nearγ. It mostly consists of massiveγ phases, a few amount ofα2 phase and a small amount of B2 phase. The as-rolled alloy is duplex microstructure and B2 disappears after rolling. With increasing deformation, the strength of TiAl plates increases. The plate with deformation of 40% has the best strength of 955 MPa. Continually increasing the deformation, the mechanical properties of TiAl plate decrease. When the deformation is small, the main plastic deformation mechanisms are dislocation sliding and climbing. With increasing deformation, mechanical twins and dynamic recrystallization begin to play important roles on plastic deformation.