Zr-2合金中应力及应变诱发氢化锆析出过程的电子显微镜原位研究

IN SITU ELECTRON MICROSCOPY STUDY ON PRECIPITATION OF ZIRCONIUM HYDRIDES INDUCED BY STRAIN AND STRESS IN ZIRCALOY-2

用电子显微镜原位研究了Zr-2合金中的氢化锆在应力及应变作用下的析出过程。应力诱发析出的氢化锆为γ相,与基体间存在(110)_γ//(1120)_(αZr),(001)_γ//(0001)_(αZr)的取向关系。γ氢化锆沿它的[110]生长最快,形成尖劈状。当沿氢化锆开裂后,在裂纹端部又将析出氢化锆。应变诱发析出的氢化锆为δ相,与基体间存在(111)_δ//(0001)_(αZr),(110)_δ//(1120)_(αZr);或(010)_δ//(0001)_(αZr),(001)_δ//(1120)_(αZr)的取向关系。形变速率越高,δ氢化锆越细小。

The precipitation hydrides induced by stress were found to be gamma phase with orientation relationship of (110)_γ//(1120)_(αZr),(001)γ//(0001)_(αZr)between γ- hydride and surrounding matrix. The growth of-hydrides exhibiter a quickest rate along [110] direction, that brings them in taper shape. After cracking at hydride matrix beundary, a new one will precipitate at the tip of cracks. This is the essential process of hydrogen-induced delayed cracking in zircaloy The pre- cipitating hydrides induced by strain were found to be delta phase Phase with both orientation relationships of (111)_δ//(0001)_(αZr)(110)_δ//(1120)_(αZr) and (010)_δ//(0001)_(αZr) (001)_δ//(1120)_(αZr) between δ-hydride and surrouding matrix. The δ-hydride becomes much finer as the strain rate increased.