Microstructure and properties of a refractory high-entropy alloy after cold working

Abstract

A refractory high-entropy alloy HfNbTaTiZr was successfully rolled at room temperature up to 86.4% reduction in thickness (true thickness strain is −2.3). This represents the first successful attempt to cold roll a HEA with a BCC crystal structure. The microstructure and properties of the rolled sheets were determined in the as-rolled condition and after annealing at 800 °C, 1000 °C, and 1200 °C. Cold rolling resulted in extensive grain elongation, formation of deformation bands within the grains, and development of crystallographic textures that depended on the rolling reduction. The 86.4% cold-rolled sheet had true tensile stress of 1295 MPa and tensile ductility of 4.7%. After annealing at 1000 °C and 1200 °C, complete recrystallization of the cold-rolled sheet occurred. After annealing at 1000 °C, the true tensile stress and ductility of the sheet were 1262 MPa and 9.7%, respectively.