Studies of oxidation behavior in Ti-base alloys

Abstract

The performance of titanium alloys depends upon oxidation resistance to atmospheric corrosion, hydrogenation and prevention processes. Oxidation is the predominant failure mode of titanium alloys, which limits use of components in gas turbine above 1073K. Resistance to oxidation in titanium alloys increases limiting temperatures. It is achieved either through bulk alloying or surface alloying. Additional alloying elements form continuous surface scales with better adherence and resistance to high temperature decomposition. Improvement in surface oxidation resistance has been accomplished by laser surface deposition/remelt, ion implantation and cementation after electro deposition and in situ surface synthesis. Hydrogenation embrittles metal after formation of hydride precipitation along grain boundaries or along defects of prestrain. In presence of greater niobium and hydrogen content beta-phases appear to soften the metal during deformation. Other routes to improve oxidation resistance include solidfreedom fabrication by laser deposition/solidification-hot working techniques, rapid solidification, powder metallurgy and foil metallurgy and directional solidification. Alternative routes too improve oxidation resistance suffer from drawback such as anomalous grain size, porosity and inhomogenity