Influence of alloying with hafnium on the microstructure, texture, and properties of Cu–Cr alloy after equal channel angular pressing

Equal channel angular pressing (ECAP) results in grain refinement of the Cu–0.7 % Cr alloy with an average grain size of 320 ± 73 nm. Addition of hafnium leads to a further decrease of average grain size down to 225 ± 82 nm and to an increase of the fraction of high angle boundaries from 40 to 53 %. The microhardness of the Cu–0.7 % Cr–0.9 % Hf alloy is higher than that of the Cu–0.7 % Cr alloy in the quenched state, after ECAP followed by annealing in the temperature interval of 400–550 °C during which aging occurs. Compared with the quenched state, ECAP increases the tensile strength of the Cu–0.7 % Cr and Cu–0.7 % Cr–0.9 % Hf alloy by a factor of 2.3 and 2.2, respectively. Aging leads to additional strengthening. Compared with the Cu–0.7 % Cr alloy, the strength of the Cu–0.7 % Cr–0.9 % Hf alloy after ECAP and after subsequent aging is 1.3 and 1.5 times higher, respectively.