FATIGUE LIVES OF GRAIN BOUNDARY AND COMPONENT CRYSTALS IN A COPPER BICRYSTAL
铜双晶体中晶界及组元晶体的疲劳寿命

Cyclic tension-tension deformation was carried out on a copper bicrystal which consists of a single and a double slip oriented component crystal. The grain boundary of the bicrystal is nearly perpendicular to the stress axis during cyclic deformation. The S-N curves of grain boundary and component crystals were respectively determined. By comparison of fatigue lives between component crystals and grain boundary, it was found that the fatigue lives of grain boundary were lower than those of component crystals, however, the fatigue lives of two component crystals showed no obvious difference under the same cyclic stress. Surface observation by SEM indicated that the probability of initiating fatigue cracks in copper bicrystal increased in the order of double, single slip oriented component crystals and grain boundary under the same cyclic load amplitude.