Microstructural evolution, wear resistance, and electrical conductivity of Cu–Ti₂SnC functionally graded composites fabricated by cryogenic deformation-driven metallurgy

Functionally graded Cu–Ti₂SnC composites were successfully fabricated by cryogenic deformation-driven metallurgy (CDDM) to achieve a superior balance between mechanical performance, wear resistance, and electrical conductivity. A five-layer architecture containing 0–20 wt.% Ti₂SnC was consolidated under continuous liquid-nitrogen cooling, which promoted severe plastic deformation while suppressing dynamic recovery and oxidation. Progressive reinforcement addition refined the average copper grain size from 3.91 ± 0.22 μm to 0.12 ± 0.08 μm, accompanied by an increase in the Zener–Hollomon parameter (lnZ) from 32.1 to 43.7. Consequently, microhardness increased from 122 ± 5 HV₀.₁ to 266 ± 6 HV₀.₁, while the friction coefficient and wear rate decreased from 0.55 to 0.37 and 6.1 to 4.8 μg m−¹, respectively. The ultimate tensile strength improved from 213.5 ± 4.8 MPa for pure Cu to 335.7 ± 6.4 MPa for the 20 wt.% Ti₂SnC layer, representing an enhancement of approximately 57%, whereas electrical conductivity remained relatively high, decreasing only from 97.4% to 83.6% IACS. The proposed CDDM approach provides an effective solid-state route for producing multifunctional Cu-based functionally graded composites with optimised strength, tribological performance, and electrical conductivity.