Ti40阻燃合金粗晶超塑性变形行为及机理

Superplastic Deformation Behavior and Mechanism of Burn-Resistant Ti40 Alloy with Large Grains

借助OM、TEM研究了高温条件下Ti40阻燃合金的粗晶超塑性变形行为及机理。结果表明:在920℃下,应变速率为5×10-5～1×10-2s-1的Ti40合金表现出良好的超塑性行为,拉伸延伸率均超过250%,应变速率敏感指数m大于0.3。超塑变形后,粗大的等轴组织细化。TEM分析表明,在变形过程中,位错运动形成亚晶界,亚晶界通过吸收滑移位错形成小角度晶界甚至大角度晶界。Ti40合金的粗晶超塑性是由动态回复和再结晶共同作用的结果。

The superplastic deformation behavior and mechanism of bum-resistant Ti40 alloy with large grains at elevated temperature were investigated by OM and TEM. Results show that Ti40 alloy exhibits excellent superplastic behavior in the strain rate range from 5× 10s to 1×10-2 s-1 at 920℃. All of the tensile elongations exceed 250% while the strain rate sensitivity index m is over 0.3. Optical microstructure shows that the large equiaxed gains are refined after superplastic deformation. TEM observation indicates that an unstable subgrain boundary formed by dislocation during superplastic deformation. The subgrain boundaries were transformed into low- and even high-angle grain boundaries by absorbing gliding dislocations. The superplastic behavior of large-grained Ti40 alloy could be explained by dynamic recovery and recrystallization.