Indentation creep behaviour of the magnesium AZ61–0.7Si–xBi cast alloys

Abstract

Creep behaviour of the AZ61–0.7Si–xBi cast magnesium alloys were studied by Vickers indentation testing under constant load of 5 N in the temperature range of 423–523 K. The results indicate that increasing Bi content improved the creep resistance at all test temperatures. This was caused by the higher volume fraction of the thermally stable Mg3Bi2 intermetallic particles, as the principal strengthening cause, which compensated the possible effects of the lower amount of the Mg2Si particles. According to the obtained stress exponents of about 6.7 and activation energies in the range of 84.6–88.1 kJ mol−1, dislocation pipe diffusion was suggested as the dominant creep mechanism.