New function of hydrogen in materials

Useful functions of hydrogen found recently in materials are reviewed with newly obtained results. By hydrogen absorption-desorption heat-treatment, grain size of Cu-Ti alloys are refined to several 10 nm. Simultaneous improvements of electrical conductivity and mechanical strength for Cu-3 mass%Ti alloy were achieved, and the values of 21%IACS and 1100 MPa were obtained, respectively. Hydrogen treatment led to a reduction in the grain size in α- and β-rich α + β type alloys to about 3 and 0.3 μm, respectively. The yield strength of fine-grained α- and β-rich α + β type alloys is greatly improved. Curie temperature of La(Fe_xSi _1-x)₁₃ compounds is controlled by the content of hydrogen. It is also demonstrated that the La(Fe_xSi_1-x) ₁₃H_y compounds can be applicable as new-type pressure sensing materials. Polymer-coated CuPd nanoparticles were synthesized by chemical reduction method, and B2 phase in CuPd alloy nanoparticles is effectively formed by the hydrogenation treatment.