Tracking the role of nitrogen in the improvement of the high temperature oxidation resistance of titanium by mechanical treatments

We report the role of ultrasonic shot-peening (SP) and laser-shock peening (LSP) on the insertion of atmospheric nitrogen during high temperature oxidation of pure titanium and the improvement of its oxidation resistance. Ion Beam analysis showed that for short oxidation durations, a layer of Ti2N is formed at the oxide-metal interface. However, only the LSP treatment leads to the formation of a long-term stable nitrogen-rich layer which acts as a barrier for the diffusion of oxygen. This explains the efficiency of the LSP treatment to reduce the oxidation of Ti and prevent embrittlement.