低氢含量工业纯钛循环变形的微观结构——Ⅰ.γ氢化物附近的晶体旋转及胞结构的形成

MICROSTRUCTURE OF CYCLICALLY DEFORMED TITANIUM WITH LOW HYDROGEN CONCENTRATION I. Crystal Rotation and Formation of Cell Structure Near Hydrides

对均匀弥散分布着γ氢化物的低氢含量的工业纯钛进行循环疲劳试验,发现在氢化物碎化之前,位错可以穿过氢化物和基体的共格界面,从而使氢化物发生剪切变形,然而在氢化物碎化之后,位错则不能继续穿过界面,而是在界面处缠结,这被归结于由于氢化物尺寸发生变化导致氢化物内部应力降低,氢化物不能继续发生剪切变形所致,透射电镜观察表明,在氢化物的内部至少能激发3套滑移系统,为了协调氢化物和基体之间的不均匀变形,在氢化物和基体内部都发生了晶体旋转,并且氢化物和基体之间的取向关系遭到了破坏,对相应的晶体旋转的机制进行了讨论。

Cyclic testes were conducted on commercially pure titanium with low hydrogen concentration, in which 7 hydrides dispersed homogenously. It was found that dislocations can transfer through the coherent interface only before the hydride was fragmented, after fragmentation, dislocations would tangle at the fragments and do not penetrate the interface again due to the decrease of the maximum stress in the fragments. At least three sets of dislocations can be activated in hydrides during the cyclic deformation. To accommodate the inhomogenous strain between the matrix and hydrides, the crystal rotation occurred in both of them. A mechanism for the crystal rotation has been proposed.