Microstructural tailoring and property enhancement of Cu–Ti2SnC composites via sequential severe plastic deformation routes

Abstract

This study investigates the microstructural evolution and property enhancement of Cu–Ti 2 SnC composites fabricated through a sequential severe plastic deformation route combining asymmetric rolling, recrystallization treatment, and cryogenic friction stir processing (LN 2 -FSP). Copper substrates were prepared in two initial states: strain-hardened (75% thickness reduction) and fully recrystallized (500 °C for 90 min). Approximately 7 wt.% Ti 2 SnC particles were introduced prior to processing to evaluate the combined effects of prior deformation and ceramic reinforcement on dynamic recrystallization, strengthening mechanisms, and electrical conductivity. The stir-zone grain size strongly depended on the initial microstructure and reinforcement. The composite produced from strain-hardened copper exhibited the finest grains (4.1 ± 0.3 μm), followed by strain-hardened copper without reinforcement (5.8 ± 0.8 μm), the composite produced from annealed copper (6.9 ± 0.4 μm), and annealed copper without reinforcement (8.5 ± 0.5 μm). Mechanical properties demonstrated a strong synergy between pre-strain and reinforcement. The composite produced from strain-hardened copper achieved the highest ultimate tensile strength (289.4 ± 12.3 MPa), yield strength (209.5 ± 12.3 MPa), elongation (29.3 ± 1.1%), and toughness (85.4 ± 1.2 MJ m -3 ). Electrical conductivity showed the typical strength–conductivity trade-off, with values ranging from 86.3 ± 1.3% to 94.3 ± 1.1% IACS for processed samples, while fully annealed copper reached 98.4 ± 1.1% IACS. The results demonstrate that combining prior asymmetric rolling with Ti 2 SnC reinforcement during cryogenic FSP enables significant grain refinement and mechanical strengthening while retaining high electrical conductivity.