Ti-6Al-4V合金高温氧化行为及显微组织

High-temperature Oxidation Behavior and Microstructure Evolution of Ti-6Al-4V

分析了Ti-6Al-4V合金在900,930,960℃下的氧化行为及表层显微组织变化。在0.5~24 h时间内,氧化层不断增厚,越靠近表面氧化层越疏松。氧含量在氧化层/富氧层界面的5μm内发生急剧下降,进入富氧层后缓慢下降直到稳定。氧化层中以TiO_2为主,同时也出现了Al_2O_3。富氧层中的a相含量远远高于基体内部,其晶粒尺寸也发生长大。富氧层深度与热暴露时间的关系可用对数函数描述,通过线性回归分析计算出了O在富氧层中的扩散激活能为206k J/mol。

This paper investigated the oxidation behavior and microstructure evolution of Ti-6Al-4V alloy at 900,930,and 960 ~oC.Results show that the thickness of surface oxide layer increases in 0.5~24 h and the closer to the surface,the more porous the oxide.There is a sharp decrease in O level at the boundary of oxide layer anda-case.The O level decreases gradually inside thea-case to a stable level in the Ti-6Al-4V base material.The oxide layer is mainly composed of TiO_2,and there is also a small amount of Al_2O_3.The volume fraction ofais much higher in thea-case and the grain size is larger.The relationship betweena-case depth and thermal exposure time can be fitted using log-log function.Linear regression analysis shows that the activation energy of O diffusion inacase is 206 k J/mol.