Plane of Crack Propagation in Stress Corrosion Fracture in Copper Beryllium Available to Purchase

Single crystals of a copper-beryllium alloy of two axial orientations ([111] and [110]) strained in tension showed slip on {111} planes. The same crystals, stressed in tension and exposed to an ammonia atmosphere, failed in a transcrystalline mode. In crystals of [111] orientation cracks propagated on (123) planes. Calculations show that in these crystals, the maximum resolved shear stress on the $(1¯11)$ slip planes is produced when the crack propagates on the (123) plane. In crystals of the [110] axial orientation, the cracks propagated on (110) planes. Again calculations show that the maximum resolved shear stress on the (111) slip planes is produced when the crack propagates on the (110) plane. These results indicate that crack propagation occurred on planes which would result in the maximum plastic deformation on the available slip system.