Microstructural peculiarities and textural characteristics of Ni–W sheet alloy after accumulative roll-bonding and annealing

Abstract

In the present study, the through thickness morphological and textural characteristics of a Ni–14W sheet, processed by accumulative roll-bonding (ARB) up to 4 cycles (e = 3.2) and annealed at 1100 °C for 1 h, were investigated using electron backscatter diffraction. In the internal layers, the microstructure exhibited a small grains size free of twins and contained high fraction of low angle grain boundaries due the domination of {001}〈100〉 Cube orientation. At the surface layers, grains were coarser and contained high fraction of twins, while texture was characterized by retained shear components. The results showed that the heterogeneity of annealed microstructure texture decreased with the increasing number of ARB processing. Particle stimulated nucleation mechanism was evidenced at the vicinity of some bonding interfaces due to the presence of metallic inclusions resulting from wire-brushing procedure. As a result, the orientation of the new recrystallized grains was rather random and the grain size was stabilized by a pining effect which contributed to the microstructure heterogeneity. A successful bonding was achieved with increasing number of ARB cycles as shown by the transformation of interfaces into grain boundaries and their subsequent migration.