Understanding the Mechanochemical Effect of High‐Pressure Torsion on AA2195–0.025 wt% Sc Alloy

The severe plastic strain‐induced mechanochemical alterations in a AA2195‐0.025Sc alloy is experimentally investigated. The alloy is subjected to high‐pressure torsion (HPT) processing at room temperature. Microstructural and microchemistry evolution is systematically characterized by scanning electron microscopy, transmission electron microscopy, and atom probe tomography techniques. Precipitate dissolution (Al 3 (LiScZr) and Al 2 Cu precipitates) and grain fragmentation occurs at an onset strain of 1.0 and continues till strain 4 resulting in disappearance of precipitates and appearance of high segregation at grain boundaries. Thereafter, at higher strains, the segregated solutes form nanoclusters at grain boundaries, triple junctions and HPT‐induced vacancy cluster sites. Diffusion calculations are performed to account for the experimentally observed changes in precipitate state by evaluating the increased atomic mobility of solutes (Li, Sc, and Zr) by HPT‐induced vacancies, dislocations, and grain boundaries. Enhanced atomic mobility of Li can be attributed to the high density of vacancies, dislocations, and grain boundaries, whereas solute drag by moving grain boundaries result in enhanced diffusion of Sc and Zr. The increase in Sc and decrease in Zr in the reprecipitated phases could be attributed to the rapid diffusion of Sc along grain boundaries along with trapping of Zr at grain boundaries.