Hardening palladium using hydrogen as a catalytic alloying element

Work hardening is one of the most widely used methods in strengthening metals by increasing dislocation density, which can be achieved by raising plastic strain and/or suppressing dynamic recovery of the dislocations upon plastic deformation. Based on the analyses on the data reported in our previous work in cold-rolled Pd-H system (Scripta Materialia, Vol. 68 (2013), p. 743), we propose a new strategy in hardening Pd using hydrogen as a catalytic element. It is shown that since the introduction of hydrogen facilitates dislocation formation and increases the dislocation density in Pd upon plastic deformation, subjected to a same deformation level and subsequent removal of hydrogen, Pd can obtain a higher hardness compared to that without hydrogenation before deformation. It is further pointed out that the proposed strategy may, in addition, be applied to other metals, which can dissolve a relatively large amount of hydrogen, e.g. magnesium, nickel and niobium.