Evolution of microstructure and crystallographic texture during cold rolling of liquid phase sintered tungsten heavy alloy

Abstract

In this study, the evolution of microstructure and crystallographic texture of two-phase tungsten heavy alloy (almost pure tungsten embedded in nickel‑tungsten‑iron matrix) during cold rolling was investigated systematically. Electron back scatter diffraction studies reflected that the matrix phase accommodates more strain in the early stages of deformation and that as deformation progresses, the matrix phase exhausts its work hardening ability, resulting in the onset of micro-shear band formation. The tungsten phase on the other hand showed the presence of large orientation gradients accompanied with significant flattening and elongation of grains. At higher rolling reductions (effective true strain of −2.66), extensive shear bands spanning across several tungsten particles and the matrix were observed in the microstructure, which in turn had implications on the evolution of the crystallographic texture. It was observed that weak αb. c. c. (<110>∥RD) and γ fiber (<111>∥ND) emerge in tungsten at low to intermediate rolling reductions, and that αb. c. c. fiber strengthens much more than γ fiber at higher rolling reductions with prominent intensity at rotated cube position. For the matrix phase, a weak beta fiber (fiber connecting the brass {011}<211>, copper {112}<111>, and S {123}<634> orientations in the Euler space) was observed at low to intermediate rolling reductions, followed by strengthening of Goss and Brass orientations at higher rolling reductions.