Transactions of Nonferrous Metals Society of China
JOURNAL OF RAILWAY SCIENCE AND ENGINEERING
|Vol. 12 No. 4 August 2002|
（High Temperature Material Research Division, Central Iron and
Steel Research In stitute，Beijing 100081, China）
Abstract:The research achievement on wrought TiAl alloys gained recently in Central Iron and Steel Re search Institute, China, was contributed. The progresses 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 also identified that breakdown of α2-Ti3Al lamellae produces new dislocation-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.
Key words: wrought TiAl; microalloying; hot deformability; microstructure