Surface and internal deoxidation behavior of titanium alloy powder deoxidized by Ca vapor: Comparison of the deoxidation capability of solid solution and intermetallic titanium alloys

The surface and internal deoxidation behavior of hydrogenation-dehydrogenation titanium alloy powder deoxidized by Ca vapor was investigated. Comparison of the deoxidation behavior of solid solution and intermetallic alloys was performed by calculating the surface and internal oxygen concentrations. The surface O concentration of the Ti alloy powders depended on the specific surface area and the thickness of the surface oxide layer. The removed surface O concentration of the solid solution alloy increased significantly with decreasing particle size. However, the removed surface O concentration of the intermetallic alloy increased slightly as the particle size decreased. The difference in the deoxidation behavior of the surface O of the solid solution alloy and the intermetallic compound alloy occurred owing to the difference in the tendency of the specific surface area to increase with the particle size and the thickness of the reduced surface oxide layer. The internal O concentration of the Ti alloy powder was uniformly reduced regardless of the particle size, and a larger amount of O was removed from the inside of the particles than from the surface.