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

Abstract

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 1350 MPa at 77 K 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.

 

This Paper was Originally Published in Japanese in J. Japan Inst. Copper 59 (2020) 299–303. Some sentences were added in the main text of this paper. References of 2) and 5–11) were newly added.

Fig. 6 Strain-rate sensitivity vs. grain size in pure Cu and the Cu–Si solid-solution alloys processed by the HPT with 5 rotations. The open squares are the data obtained from the literature by Wei et al. for pure Cu.¹⁴⁾