Effect of ARB and High Temperature Annealing on the Microstructural Evolution and Mechanical Response of Cu–Al–Ag Shape Memory Alloys

Abstract

Abstract

This work employs accumulative roll bonding (ARB) to generate ultrafine-grained Cu–Al–Ag laminates prior to annealing. Subsequent high-temperature annealing produces the coarser microstructures required for martensitic phase development. High-purity aluminum and copper strips were combined with silver particles as the starting materials. The aluminum level was kept constant at 15 wt.%, while the silver content was adjusted to 2.5, 5, and 7.5 wt.%. After ARB processing, the multilayered composites were annealed for one hour at 700–1100 °C and then quenched to room temperature. The study focuses on how silver concentration and annealing temperature influence the resulting microstructure. All processed samples developed refined grains and elevated dislocation densities. Heat treatment produced new intermetallic compounds. Alloys containing 2.5 wt.% Ag mainly formed Cu9Al4, whereas those with5–7.5 wt.% Ag stabilized orthorhombic Cu3Al martensite. The presence of martensite increased strength and microhardness at room temperature. The highest martensite content appeared in the 900–1000 °C annealing range. The annealed and quenched composites demonstrated strong shape memory performance at ambient conditions.