Effect of hot forging-annealing on microstructure and mechanical properties of lightweight refractory high-entropy alloys

Lightweight refractory high-entropy alloys (LRHEAs) exhibit significant application potential in aerospace and other fields due to their excellent high-temperature stability and the synergistic effects of high strength and good plasticity. However, casting defects arising during large-scale preparation severely hinder their engineering applications. In this study, TiZrVNbAlMo alloys were subjected to multi-pass hot forging and annealing to systematically investigate the evolution of their microstructure and mechanical properties. The results demonstrate that hot forging combined with annealing effectively eliminates as-cast porosity and refines the grain size through dynamic recrystallization (DRX). It was also found that pore defects induce continuous DRX (CDRX) during the initial forging pass by impeding dislocation motion, whereas subsequent forging becomes dominated by discontinuous DRX (DDRX) due to the elimination of porosity. This multi-step process refines the grain size of the alloy to approximately 90 μm and promotes effective dislocation interactions during plastic deformation, leading to a substantial increase in fracture elongation from 11 ± 5% to 29 ± 2%, while maintaining a high strength of 1049 ± 20 MPa. This study provides theoretical and technological support for the industrial-scale production of LRHEAs.