爆轰载荷下TB6钛合金组织及绝热剪切行为研究

Microstructure and Adiabatic Shear Behavior of TB6 Titanium Alloy under Detonation Load

摘要:

采用电子背散射衍射技术（EBSD）研究了双相TB6钛合金在超高应变速率的爆轰载荷下绝热剪切带（ASB）中心、过渡区及基体的组织、织构演变。结果表明，爆轰后α、β相晶粒尺寸均减小，α相产生{10"1" ?2}孪晶；ASB中心区β相晶粒发生了动态再结晶，晶粒尺寸400 nm，绝大部分为大角度晶界，位错密度最低，ASB中心发生α→β相变；{10"1" ?0}⊥AD、<0001>//RD or ND、{100}<110>旋转立方存在于除了爆轰基体的所有α或β相中；{10"1" ?0}<0001>、{10"1" ?0}<11"2" ?0>织构存在于原始组织的α相中，过渡区存在{10"1" ?0}<0001>、{10"1" ?0}<11"2" ?0>、{11"2" ?0}<0001>三种织构，{100}<001>伪立方织构只存在于爆轰基体的β相中；{100}//SD是ASB组织的共同特点，<0001>//AD织构存在于爆轰基体、{11"2" ?0}//SD、<0001>//SD织构存在于ASB中心；α相的{11"2" ?0}面、<0001>取向和β相的{110}面平行于ASB，这均不是密排面和密排方向，不利于合金的机械性能。

Abstract:

The microstructure and texture evolution of the center of the adiabatic shear band (ASB), transition region and substrate of the dual-phase TB6 titanium alloy under detonation loading at ultra-high strain rates were investigated by electron backscatter diffraction (EBSD). The results show that the grain size of α and β phases decreases after detonation. The α phase produces {102} twins. The β phase grains in the central region of ASB undergo dynamic recrystallization, the grain size is 400 nm, most of them are high-angle grain boundaries, and the dislocation density is reduced. The α→β phase transition occurs in the ASB center. {100}⊥AD, <0001>//RD or ND, {100}<110> rotating cubes are present in all α or β phases except the detonation matrix; {100}<0001>, {100}<110> texture exists in the α phase of the original structure, and there are {100}<0001>, {100}<110>, {110}<0001> three textures in the transition region, {100}<001> pseudo cubic texture exists only in the β phase of the detonation matrix. {100}//SD is a common feature of ASB organization, <0001>//AD texture exists in the detonation matrix, {110}//SD, <0001>//SD texture exists in the ASB center. The {110} plane, <0001> orientation of α phase and the {110} plane of β phase are parallel to ASB direction, which are not belong to close-packed planes and dense-packed directions, which are not conducive to the alloy"s mechanical properties.