【摘要】 通过等温拉伸实验研究双态组织Ti-6Al-2Zr-1Mo-1V合金的热变形行为、显微组织演变与断裂特征。结果表明:材料的流动软化由双态组织动态球化引起,并导致较高的应力指数和热激活能。结合SEM、EBSD和TEM显微组织观察发现,750和800°C下动态球化由α/α亚晶界的形成与β相的渗透共同导致;而在850°C下由于低角度晶界向高角度晶界转化,生成呈项链状分布的细小晶粒,证明该温度下主要的球化机制为动态再结晶。随着变形温度的升高或应变速率的减小,合金的断裂机制由微孔聚集向沿晶断裂转变。更多还原

【Abstract】 The hot deformation behavior, microstructure evolution and fracture characteristics of bimodal microstructured Ti-6 Al-2 Zr-1 Mo-1 V alloy were investigated by isothermal tensile tests. Results reveal that flow softening is caused by dynamic globularization of the bimodal microstructure, which also results in a relatively high stress exponent and thermal activation energy. The corresponding SEM, EBSD and TEM observations indicate that the dynamic globularization at 750 and 800 °C is accomplished by the formation of α/α sub-grain boundary and penetration of the β phase. However, dynamic recrystallization(DRX) is the main globularization mechanism at 850 °C, which was proved by the generation of fine grains with a necklace-like character due to the transformation of low-angle boundaries (LABs) into high-angle boundaries (HABs). With an increase in the deformation temperature or a decrease in the strain rate, the fracture mechanism changes from microvoid coalescence to intergranular fracture.更多还原