Effect of grain boundaries on bending fatigue life of aluminum bicrystals with 0.5 schmid factor on primary slip systems

In order to examine the effect of grain boundaries on cyclic bending behavior, three types of aluminum bicrystals having a Schmid factor of 0.5 for the primary slip system of each component crystal and different disparities in plastic strain on the primary slip system between two component crystals were prepared by the Bridgman method. The component crystals A and B, the pseudo-bicrystals without grain boundary and the real grown bicrystals were investigated under the constant strain amplitude of 0.13% and cyclic frequency of 30.4 Hz at room temperature. The mixed model bicrystals without grain boundaries were prepared by joining two component crystals A and B. The cyclic saturation moments at 1000 cycles of the pseudo-bicrystals and the mixed model bicrystals were almost equal and were lower than that of real grown bicrystals with grain boundaries. It was suggested that the existence of grain boundaries contributed to the increase in the saturation moments and possibly shortened the fatigue lives.