Evolution of deformation microstructures of cold-rolled Ta-2.5W alloy with coarse grains at low to medium strains

摘要

Ta-2.5W alloy with coarse grains was cold-rolled to reductions ranging from 5 to 40%. The evolution of the microstructure was investigated by optical microstructure, electron backscatter diffraction (EBSD). A few microbands appear when the reduction reaches 20%. The density of microbands increases with increasing reduction. When the reduction reaches 40%, grains are composed of one or two groups of microbands except the {001}< 110 > orientations. Most of the inclination angle between microbands and RD in this condition is 20-35 degrees. As the strain increases, the inclination angle between microbands and RD gets smaller. The habit plane of microbands can be {110} plane. The microbands and matrix usually share a common < 110 > or < 111 >. The mature body-centered cubic rolling texture, including alpha and gamma fibers, is not developed until the reduction reaches 40%. Meanwhile, shear bands appear. New grains can be seen in shear bands and a model is proposed to explain this process. (C) 2015 Elsevier Ltd. All rights reserved.y