Investigation of dynamic recrystallization, grain growth and material flow in friction consolidated aluminum alloys using EBSD and X-ray μCT

In this study, the interplay between grain morphology and crystallographic texture evolution is investigated within friction consolidation (FC), a newly emerging solid-state recycling technology. Employing comprehensive electron backscatter diffraction analysis, microstructural development is primarily controlled by continuous dynamic recrystallization, along with discontinuous dynamic recrystallization that occurs prior to entering the FCed region. The compressive strain experienced by the sample during FC increases the aspect ratio of the grains, suppressing geometric dynamic recrystallization. Subsequently, two distinct grain growth mechanisms are identified: Texture-induced grain convergence dominates early-stage FC and thermally activated grain growth dominates at prolonged processing. The imposed shear deformation produces simple shear texture with a dominant B/B texture alongside minor A1∗/A2∗ and C texture components. Additionally, a multi-layer material flow structure forms at the bottom of the FCed region and decouples from the subsequent material flow, revealing the reason for the observed saturation in consolidation depth as processing time increases. At prolonged processing time, mechanical property gradients are reduced, especially near material flow boundaries. The slight improvement in yield strength and ultimate tensile strength is attributed to an increased precipitate volume fraction as confirmed by high-energy X-ray diffraction (HEXRD) analysis.