Thermal deformation characteristics of AlMo0.8NbTiW0.2Zr refractory multi-principal element alloy

Abstract

Thermal deformation characteristics of a multiphase AlMo0.8NbTiW0.2Zr refractory multi-principal element alloy (RMPEA) prepared by powder metallurgy (P/M) were investigated using isothermal compression at temperature range of 1150–1350 °C and the strain rate of 10−4–10−2 s−1. The apparent activity energy (Q) for high-temperature deformation of AlMo0.8NbTiW0.2Zr was evaluated as 293–323 kJ mol−1 from the stress-strain data obtained from the hot-compression tests. The values of the stress exponent (n) were in a range of 2.51–2.84 at the strains of 0.35–0.69. At higher deformation strain rate, the discontinuous dynamic recrystallization (DDRX) mechanism became more obvious with increasing temperature. While at higher deformation temperature, the dominant dynamic recrystallization (DRX) mechanism gradually changed to the continuous dynamic recrystallization (CDRX) mechanism with decreasing strain rate. The intermetallic-growth-induced unidirectional bulging grain boundaries at low deformation temperature and high strain rate were beneficial to the nucleation of DDRX. The precipitated needle-like Zr-rich phase would promote the processing of CDRX at the deformation condition of high deformation temperature and low strain rate.