Two kinds of Cu bicrystals, with a high-energy grain boundary and a coherent twin boundary parallel to the loading direction respectively, were cyclically deformed to reveal the fatigue cracking mechanisms. It was shown that intergranular fatigue cracking occurred firstly in the bicrystal with the grain boundary, while the persistent slip bands became the preferential cracking sites in the bicrystal with a twin boundary. These results indicate that the twin boundary had an intrinsically higher fatigue cracking resistance than the grain boundary.

Higher Fatigue Cracking Resistance of Twin Boundaries than Grain Boundaries in Cu Bicrystals. L.L.Li, Z.J.Zhang, P.Zhang, Z.F.Zhang: Scripta Materialia, 2011, 65[6], 505-8