EFFECT OF GRAIN BOUNDARY ON FATIGUE BEHAVIOUR OF Al BICRYSTALS
LI Qingsheng (Chingshen Li);T. BRETHEAU Taiyuan University of Technology University Paris Nord Department of Mathematics and Mechanics;Taiyuan University of Technology; Taiyuan 030024
Cite this article:
LI Qingsheng (Chingshen Li);T. BRETHEAU Taiyuan University of Technology University Paris Nord Department of Mathematics and Mechanics;Taiyuan University of Technology; Taiyuan 030024. EFFECT OF GRAIN BOUNDARY ON FATIGUE BEHAVIOUR OF Al BICRYSTALS. Acta Metall Sin, 1990, 26(3): 55-60.
Abstract The effect of grain boundaries on cyclic deformation and fatiguecrack growth in Al bicrystals under stress controlling in laboratory atmospherehas been studied. The effect of a grain boundary is found to be restricted in anarrow area, termed as grain boundary affecting zone (GBAZ), where the incom-patible plastic strain by the two sides of the interface under cyclic loads creats in-ternal stress which conversely promotes inhomogeneous slip in the area and grainboundary cracking. As an extended stage I crack initiated from a notch approachesthe grain boundary under a constant cyclic load, the crack branches, the crackfront splits into several pieces, meanwhile, the growth rate reduces to a minimumvalue at the centre of GBAZ. Such microstructure-sensitive growth of extendedstage I cracks is mainly attributed to the grain boundary-induced crack tip shielding.
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