Effect of zirconia on low cycle fatigue and energy absorption of molybdenum alloy

Abstract Pure molybdenum and ZrO2 dispersion strengthened Mo alloy were prepared by liquid-liquid doping method. The effects of adding ZrO2 on their microstructure and properties were investigated by tensile test and low cycle fatigue (LCF) test at room temperature, and the fracture mode and energy absorption were analyzed. The research shows that ZrO2 can refine the grain size and increase the recrystallization temperature of molybdenum alloy. The enhancement of yield strength by ZrO2 is mainly reflected in grain boundary strengthening. The tensile fracture mode is related to grain size, and changes from transgranular fracture to transgranular-intergranular fracture with the decrease of grain size. At the initial stage of the cycle, the increase of strain amplitude changes the cyclic hardening into cyclic softening, and the addition of ZrO2 accelerates the cyclic hardening/softening. With the increase of strain amplitude, the loading energy and absorption energy of a single stable cycle increase, while the unloading energy is basically unchanged. ZrO2 can increase the total fatigue absorption energy of molybdenum alloy at the same strain amplitude, and the single cycle absorption energy is lower than that of pure Mo, thus increasing the fatigue life.