Hydrogen effects in [001] oriented nickel-base superalloy single crystals

The entry and subsequent interaction of hydrogen on the mechanical properties of the single crystal nickel-base super alloy CMSX-2 has been studied. Significant amounts of hydrogen were introduced by high temperature hydrogen charging in molten salts which led to an increased lattice parameter and microhardness and to a degradation in tensile elongation to failure whose extent scales with the depth of the hydrogenated zone. In this region a fracture mode change from a {111} to a {100} type also occurred. The values of the binding energy of hydrogen to solidification voids and the effective hydrogen pressure in the voids were estimate.