Effects of ionizing radiation and thermal cycling on tensile properties of extruded Mg–Zn–Y–Zr alloys containing quasicrystalline phase

Effects of ionizing radiation and thermal cycling simulated low-earth orbit (LEO) environments on tensile properties of three kinds of as-extruded Mg–Zn–Y–Zr alloys at room temperature have been studied for the first time. Results show that Alloy 2 containing 2.3% Y (wt.%) possesses the optimal tensile properties among the three kinds of alloys. Significant difference between the alloys performed ionizing radiation is in elongation which show increase after radiation in Alloy 3. This may result from combined effect of the grain growth and a possible transformation between W-phase and quasicrystalline phase during the radiation process. Similarly, there are possibly two kinds of opposing effects simultaneously operated on tensile properties of the alloys during the thermal cycling process. One is softening effect initiated at the interface between the second phases and α-Mg matrix. The other is strengthening effect of dislocations generated at the grain boundary and the precipitates and particles of the second phases. Therefore, there is a decrease in strength and ductility after 200 cycles but an increase after 500 cycles which could be due to an overriding effect of hardening during cycling over the softening effect.