Thermal stability of hierarchical and multiphase nanolaminated TiZrAlV

Abstract

Abstract Microstructures, thermal stabilities and microstructures and properties evolutions of a new β TiZrAlV alloy have been investigated in this paper. Various hierarchical and multiphase nanolaminated (HMN) structures have been successfully produced in the alloy via appropriate thermomechanical processing treatments. The higher thermal stability (Tp ~ 275 °C), i.e., onset temperature of phase transformation, is achieved in a specific HMN structure consisting of nanoscale acicular isothermal α″ martensites, submicroscale α plates and large microscale primary αp grains, compared with that (Tp ~ 105 °C) of its coarse-laminated counterpart without primary αp grains. For this specific HMN structure, thermal exposures at 300–400 °C lead to further precipitation of isothermal α″ martensites, which enhances evidently the strength and reduces the ductility, while the reverse transformation of α″/α to β and the coarsening of previously formed α plates concur during thermal exposures at 500–600 °C, which leads to dramatically decreased strength and increased ductility.