Coarsening behavior of Ti2Cu phase of Ti14 alloy during isothermal thermal exposure

Abstract:

The static coarsening behavior of Ti14 alloy with Ti2Cu phase during long term exposure at 500°C was investigated. The growth of precipitated phase is determined to be controlled by the diffusion mechanism revealed by the morphology variation during thermal exposure. The static coarsening processes are uncovered to be composed of rapid coarsening stage and stable coarsening stage, which are controlled by volume diffusion with LSW model. The rapid coarsening stage is mainly dominated by the terminal migration mechanism, and the stable coarsening stage is proceeded mainly by Oswald ripening mechanism. The rapid coarsening of the Ti2Cu phase initiates the strengthening of the second phase and effectively improves the plasticity in the rapid coarsening stage. But in the stage of stable coarsening, the increase in Ti2Cu phase increases the effective slip length and further affect the crack nucleation resistance, thereby reducing the tensile plasticity of the Ti14 alloy.