VISCOUS AND RHEOLOGIC SUPERPLASTIC TECHNIQUE

ＶＩＳＣＯＵＳＡＮＤＲＨＥＯＬＯＧＩＣＳＵＰＥＲＰＬＡＳＴＩＣＴＥＣＨＮＩＱＵＥ①ＨｅＹｕｅｈｕｉ，ＨｕａｎｇＢａｉｙｕｎａｎｄＬｉｕＹｏｎｇＰｏｗｄｅｒＭｅｔａｌｕｒｇｙＲｅｓｅａｒｃｈＩｎｓｔｉｔｕｔｅ，ＣｅｎｔｒａｌＳｏｕｔｈＵｎｉｖｅｒｓｉｔ...

A new viscousrheologic superplastic technique for TiAl based alloy has been explored successfully, which can be divided into three stages: accelerated deformation at large load, viscousrheologic deformation at low load and final deformation at increasing load. In above three stages, three respective deformation mechanisms exist: coerced grain boundary movement, grain boundary viscousrheologic sliding, grain boundary sliding aided by sliding inside grains. The damage of recrystallization and neck shrinkage on superplasticity can be avoided in this technique.