Thermal activation approaches to deformation mechanisms for high Nb containing TiAl base alloys
来源期刊：中国有色金属学报(英文版)2002年第6期
论文作者：刘自成 王艳丽 林均品 张卫军 陈国良
文章页码：1081 - 1086
Key words：TiAl; thermal activation approach; deformation mechanisms
Abstract: The deformation mechanisms in a wide temperature range from room temperature to 1200K were investigated by thermal activation approach. Using observed instantaneous stress response to the strain rate jump (Δσtr), the activation volume Va, then the activation enthalpy ΔH, activation free enthalpy ΔG and activation entropy ΔS were calculated. The apparent activation energy of high temperature deformation is estimated to be 3.66eV, which is larger than the self-diffusion coefficient of binary TiAl (3.01eV). The dislocations at 1173K are generally curved or bowed, even helical-shaped dislocations. The climb of ordinary dislocations as well as twinning has greatly contributed to the plastic deformation. The CRSS at 1173K is estimated to be 180MPa. The higher resisting stress at both room temperature and elevated temperature might relate to the high Nb content of the alloy.
