Texture evolution and strengthening mechanism of single-crystal Cu-2wt%Ag alloy during continuous drawing

Abstract

Ultrafine (30 μm diameter) Cu-2wt%Ag alloy wires were fabricated by cold drawing directionally solidified <111>-oriented single-crystal rods (φ6 mm) to a total deformation of 99.998 %. This study systematically investigates the evolution of texture, mechanical properties, and strengthening mechanisms, revealing significant heterogeneity in texture development across the wire's cross-section. The central region evolved from its initial <111> orientation to a dual <111>+<100> texture, with the <100> component arising from deformation band fragmentation. In contrast, the texture evolution in the edge region was more complex: at low deformation, deformation bands with <112> orientations formed with threefold rotational symmetry; at high deformation, these bands rotated to a <100> orientation, resulting in a final <111>+<100> texture. Concurrently, the matrix <111> component was stabilized via a <111>→<110>→<111> rotation path. The final 30 μm wire exhibited an excellent combination of high tensile strength (955.8 MPa) and good electrical conductivity (80.3 % IACS). Quantitative analysis identified grain boundary, dislocation, and texture strengthening as the primary strengthening mechanisms, while the proliferation of transverse grain boundaries was identified as the primary contributor to the increase in electrical resistivity.