High-Temperature Tensile Behavior of an As-Cast Ni-W-Co-Ta Medium–Heavy Alloy

Abstract

High-temperature tensile experiments with tensile rates ranging from 0.01 s−1 to 10 s−1 were carried out at various temperatures ranging from 1000 °C to 1250 °C with a Gleeble-3800 thermal simulation tester to evaluate the physical properties of an as-cast Ni–W–Co–Ta medium–heavy alloy. The microstructure evolution of the alloy during high-temperature stretching was characterized by metallographic microscopy, scanning electron microscopy, and transmission electron microscopy. The results indicated the emergence of multiple slip lines and the parallel arrangement of dislocations in the grain of the alloy after high-temperature stretching, and typical characteristics of plane slipping were observed. The plasticity of the Ni–W–Co–Ta medium–heavy alloy increased, but its strength decreased with an increase in the deformation temperature. In contrast, an increase in the strain rate resulted in a noticeable increase in the strength and plasticity of the medium–heavy alloy. The experiments revealed that the maximum tensile strength of the as-cast Ni–W–Co–Ta medium–heavy alloy was 735 MPa (T = 1000 °C, ε˙ = 10 s−1). Additionally, the maximum reduction in area and elongation was 38.1% and 11.8% (T = 1250 °C, ε˙ = 10 s−1), respectively. The mode of fracture after high-temperature tensile deformation was brittle fracturing.