氢对裂尖断裂过程影响的透射电镜原位观察

TEM In-Situ Observation of Hydrogen Effect on the Crack Tip Fracture

利用带有拉伸台的透射电镜观察了面心立方金属镍单晶体裂纹尖端的断裂过程。观察表明：随载荷增加，裂纹出现锐化、钝化、再锐化的现象，并且裂纹均以形变带中空洞萌生、长大，裂纹与空洞相连的方式扩展。但氢促进形变带减薄，加速裂纹与空洞的相连，而且氢易使裂纹以较大的“Ｚ”字形呈Ⅱ型裂纹扩展。

The crack tip fracture characteristics of the nickel single crystal were observed by an in-situ technique inTEM equipped with tensile stage. It was shown that the crack tip becomes sharp,blunt with voids and thensharp again with tensile stress increase. The crack advance mode is the nucleation,growth and coalescence ofholes in deformation band and joins the crack tip with voids. The crack easily propagates in mode I.The effectsof hydrogen are to localize the deformation zone and promote the crack joining the void.The crack easily ad-vances in mode II with zigzag crack.