Transformation mismatch plasticity in Pd induced by cyclic hydrogen charging

Abstract

Transformation mismatch plasticity is achieved in swaged palladium wires by cyclical hydriding–dehydriding. Upon multiple cycles at ambient temperature, a total strain of ∼40% is accumulated under a constant tensile stress. This value is much higher than the tensile ductility for swaged Pd subjected to monotonic deformation without transformation (<2% for this wire). Strain increments after a single cycle are proportional to the applied stress, in agreement with the Greenwood–Johnson equation for transformation mismatch plasticity. The yield stress of hydrogen-cycled Pd calculated from this equation is 760 MPa, which is much higher than the value of the original wire and about 50% higher than previous values reported for Pd that was hydrogen cycled at 100 °C without an applied stress.