Tensile Deformation Behavior of High-Strength Nanostructured Cu-Si Solid-Solution Alloys Processed by Severe Plastic Deformation

Tensile deformation behavior of high-strength nanostructured Cu-Si solid-solution alloys processed by high-pressure torsion (HPT) with 5 rotations was investigated at room and low temperatures. With increasing Si concentration, tensile strength of the nanostructured Cu-Si solid-solution alloys was significantly increased. The maximal tensile strengths were 980 MPa at room temperature, and 1350MPa at 77K in a Cu-2.04 wt.%Si alloy. This significant strengthening was achieved by grain refinement and increased dislocation density through severe plastic deformation (SPD) with the effect of Si addition on the decreasing stacking fault energy of the Cu-Si alloy. With increasing Si concentration, strain-rate sensitivity m of the nanostructured Cu-Si solid-solution alloys was decreased due to the increased dislocation density, resulting in accelerating plastic instability of tensile specimens, caused by the diminishing strain-rate hardening capacity after necking.