Recent advances of wrought TiAl alloys

1　ＩＮＴＲＯＤＵＣＴＩＯＮＴｗｏ ｐｈａｓｅ ｇａｍｍａＴｉＡｌａｌｌｏｙｓｈａｖｅｇｏｏｄｓｔｒｅｎｇｔｈｒｅｔｅｎｔｉｏｎａｂｉｌｉｔｙａｔｈｉｇｈｔｅｍｐｅｒａｔｕｒｅｓｗｈｉｃｈ ,ｉｎｃｏｍｂｉｎａｔｉｏｎｗｉｔｈｌｏｗｄｅｎｓｉｔｙ ,ｍａｋｅｓｔ

Recent advances of wrought TiAl alloys

The research achievement on wrought TiAl alloys gained recently in Central Iron and Steel Research Institute, China, was contributed. The progress es mainly include the improved hot deformability and homogenized microstructure after hot deformation due to the significant effects of micro-alloying process. Isothermal compressive test indicated that the TiAl containing minor Ni exhibits better plastic flow behavior and enlarged process window. The effect of Ni on modifying hot deformability of TiAl can be enhanced by incorporated addition of Mg . TEM observations suggested that Ni addition activates dislocations as well as twins at beginning stage of hot deformation and thereafter the higher-density dislocations promote the dynamic recrystallization inside γ-TiAl lamellae. It is a lso identified that breakdown of α2-Ti3Al lamellae produces new disloc ation-free γ-TiAl grains. On the other hand, the homogeneity of deformed microstructure can be increased by transforming the microstructure of the Ni-containing TiAl fro m original lamellar structure to equiaxed grains before hot deformation.