The crack model of ti - 2al - 2 . 5zr is proposed as follows : ( a ) hydrogen diffuse to the crack tip under applied stress ; ( b ) precipitation of hydride ; ( c ) crack propagation by hydride and precipitation through autocatalytic process ; ( d ) repeat the former steps ; ( e ) final fracture 该合金氢致延迟断裂的机理为： h ）氢在应力作用下向裂纹尖端扩散； （ b ）在裂纹尖端形成氢化物并长大： k ）主裂纹沿氢化物扩展； m重复h人比、 （ c ） ； k ）最后断裂。
