Novel strength-electrical conductivity synergy in Cu-based composites reinforced with TiZrNbTa high entropy alloy

An ultra-high strength TiZrNbTa (TZNT) high-entropy alloy (HEA) with good plasticity was attempted as a new reinforcing phase, which is introduced in the highly conductive Cu matrix to fabricate high-strength conductive composites. This work utilized a combination of a two-step ball milling method (first HEA mechanical alloying followed by fabrication of TZNT HEA/Cu hybrid powder) and a spark plasma sintering process to prepare the bulk TZNT HEA/Cu metal matrix composites (MMCs). Remarkably enhanced mechanical properties of the designed TZNT HEA/Cu MMCs with increasing TZNT contents were characterized while the electrical conductivity declined. Compared to the strength of the copper matrix, the strength of the fabricated 50 wt% TZNT/Cu specimens increased up to 340% induced by the second phase strengthening effect. The combination of grain boundary strengthening and dislocation strengthening contributed relatively less to the overall strength improvement of the composites. The TZNT/Cu composites were found to be a new insight into the high-strength conductive material preparation by choosing TZNT HEA with superior strength as hard secondary phase in copper matrix.