Influence of hydrogen-induced ordering on the tensile and fatigue characteristics of the alloy system Pd1 − xMnx (x = 0.1–0.25)

Tensile, microhardness and fatigue tests were carried out on palladium-manganese alloys with manganese contents in the range 10–25 at.%. Each alloy was examined in three structural forms: a disordered form, an Al3Zr-ordered form and a hydrogen-induced L12-ordered form. While the disordered and Al3Zr-ordered forms of a particular alloy have quite similar mechanical properties, the L12-ordered form of the alloy differs markedly from the others. It has been found that the L12-ordered form of an alloy has enhanced strength and hardness, together with reduced ductility and fatigue life, compared with either the disordered or Al3Zr-ordered forms. These differences are attributed to the formation of a hydride phase in each alloy during the preparation of the L12-ordered structure.