Nanoindentation study of hydride diffusion layer in commercial pure titanium

Abstract In this work, the mechanical properties of hydride diffusion layer were thoroughly researched by nanoindentation technique. For the first time, the clear section microstructure of hydride diffusion layer was revealed under scanning electron microscope with complicated interactions of hydride plates near the interface between hydride layer and titanium matrix. The hydride layer section has higher hardness and lower modulus towards titanium matrix due to the hard nature and easier crack nucleation of hydride precipitation. Besides, the hardness of titanium matrix shows considerable anisotropy. The anisotropic hardness of sample surface was studied before and after hydrogen charging. The hardness of titanium matrix decreases with the increase of deviation angle between c-axis and surface normal. The hydride layer formed in the titanium grain with more favorable orientation for hydride transformation tends to possess higher indentation hardness.