A refractory multi-principal element alloy with superior elevated-temperature strength

Abstract

A multiphase AlMo0.8NbTiW0.2Zr refractory multi-principal element alloy (RMPEA) with superior elevated-temperature strength was prepared by the powder metallurgy (PM). The as-sintered RMPEA was composed of BCC matrix, lath-like B2 phase, and two Al-Zr hexagonal structure phases. The alloy (ρ = 7.07 g/cm3) exhibited a superior specific compressive yield strength of 153.3, 107.8 and 54.7 MPa cm3/g at the temperature of 1423, 1523 and 1623 K, respectively, which were remarkable in the current designed refractory alloys. After compressing at 1423 K, the AlMo0.8NbTiW0.2Zr consisted of a band-like or blocky Zr5Al4-type phase and the BCC matrix, in which embedded amounts of spherical B2 nanoparticles with a size of 5–10 nm. The superior elevated-temperature compressive yield strength of the RMPEA at 1423 K is primarily ascribed to both the stabilization of the martensitic-transformation Zr5Al4-type submicron-sized phase and the precipitation of the B2 nanoparticles, afterwards impede the deformation flow.