Metals and Materials International ( IF 3.5 ) Pub Date : 2021-09-09 , DOI: 10.1007/s12540-021-01037-z Yan Feng 1 , Jie Li 1 , Xinhua Yang 1, 2
Aim
As the first step to study the fatigue crack propagation, the molecular simulations were performed to investigate the opening, propagation and closure behaviors of intragranular and intergranular cracks in nanocrystalline Ni under single-cycle mode I loading. The atomic crack angle was proposed to characterize the crack-tip blunting and sharpening quantitatively. There are obvious different mechanisms between intragranular and intergranular crack propagation. Intragranular crack propagation could be induced by stacking faults and can change its direction very easily, but the intergranular crack perpendicular to the loading direction would propagate along the grain boundary and encounter strong resistance at the triple junction. New cracks could form in the grain boundaries ahead of the original crack. Different from the traditional understanding for intragranular and intergranular cracks, however, the dislocation density increases even in the unloading process and the crack tip is possibly sharpened temporarily during loading.
Graphical abstract
中文翻译:
单循环模式I加载下纳米晶Ni的晶内和晶间裂纹扩展
目的
作为研究疲劳裂纹扩展的第一步,进行了分子模拟以研究在单循环模式 I 加载下纳米晶 Ni 中晶内和晶间裂纹的张开、扩展和闭合行为。提出了原子裂纹角来定量表征裂纹尖端的钝化和锐化。晶内裂纹扩展和晶间裂纹扩展有明显不同的机理。晶间裂纹扩展可以由堆垛层错引起并且很容易改变其方向,但垂直于加载方向的晶间裂纹将沿晶界扩展并在三重结处遇到强阻力。新的裂纹可能会在原始裂纹之前的晶界中形成。