Effect of rolling reduction on the texture evolution and mechanical properties hot-rolled WMoTaV refractory high entropy alloy with interfacial segregation

Abstract

The microstructural modification of refractory high entropy alloys (RHEAs) during rolling is a recognized technology for improving their mechanical properties, but limited researches are available for the internal coupling of macroscopic deformation and grain orientation evolution. In the present work, a single BCC WMoTaV RHEAs was hot-rolled to different reduction in thickness. The evolution process of their microstructure, texture and mechanical properties was fully tracked. A distinct BCC W-enriched nanolayer exists in hot-rolled WMoTaV RHEAs. This nanolayer effectively hinders the grain orientation of the alloy during hot deformation. Eventually, the angle differences between rolled grains c-axis and ⟨001⟩ basal texture is mainly concentrated in 0–70°, no texture component with 70°–90° appears. This is distinct from the ubiquitous rolling grain orientation. Moreover, the dominant strong basal ⟨001⟩//ND texture and ⟨111⟩//ND textures exist in rolling grains with 0–20° and 45°–70°, respectively. Under large rolling reduction, the strong basal texture alters to suppress deformation. At the same time, non-substrate dislocation slip is activated to adapt to larger plastic deformation to synergistically improve yield strength-plasticity.

The geometrically necessary dislocations (GND) density also increases and distributes uniformly to coordinate microscopic deformation and maintain strain continuity. Under the joint contribution of grain boundary, dislocation and texture, the rolling sample with 60 % reduction achieves an ultrahigh yield strength (1524 MPa) and plasticity (8.1 %) trade-off along the rolling direction compared to typical RHEA alloys. These findings hold promise for further optimizing alloy properties.