Textural Changes in Hot Compression of Disintegrated Melt Deposition (DMD)–Processed AZ31-1Ca-1.5 vol. % Nano-Alumina Composite

Abstract

Abstract The development of texture in AZ31-1Ca-1.5 volume percent (vol. %) nano-alumina composite subjected to uniaxial compression is studied over large ranges of temperature and strain rate, and correlated with operative slip systems in the various domains of its processing map. The initial rod, synthesized via disintegrated melt deposition and subsequently extruded, has a fine grain size (2–3 μm) and basal texture with (0001) planes parallel to the extrusion direction. The processing map exhibits four domains: Domain 1: 250–350°C and 0.0003–0.01 s−1, Domain 1A: 350–410°C and 0.0003–0.01 s−1, Domain 2: 410–490°C and 0.002–0.2 s−1, and Domain 3: 325–410°C and 0.6–10 s−1. Microstructures in these four domains revealed dynamic recrystallization, although the mechanisms of slip and recovery are different. In Domain 1, basal slip is the dominating mechanism that produced strong basal textures. Recovery occurs via dislocation climb controlled by lattice self-diffusion, which is promoted by the fine grain size in the starting material. In Domain 1A, prismatic slip is the major deformation mechanism and the basal texture is reduced, and the prismatic planes are tilted towards the compression axis. At higher temperatures of Domain 2, in addition to basal and prismatic slip, pyramidal slip occurs, and cross-slip among the multiple intersecting slip planes is the recovery mechanism that destroys the initial basal texture. At higher strain rates, at which Domain 3 occurs, non-basal slip (prismatic and pyramidal) activity is higher than that for basal slip, and the basal texture is reduced, giving way to favorable prismatic slip orientations. The recovery in this domain occurs via dislocation climb, which is controlled by grain boundary self-diffusion. The activation parameters, tensile ductility, and fracture features further support the conclusions on the rate-controlling mechanisms occurring in each domain.