In situ damage assessment in a cast magnesium alloy during very high cycle fatigue

Damage evolution during very high cycle fatigue (VHCF) in AXJ530 die-cast magnesium alloy was studied in situ using nonlinear ultrasonic measurements via analysis of the feedback signal of a closed-loop ultrasonic fatigue system. Variations in acoustic nonlinearity with fatigue cycles revealed cyclic hardening/softening during early fatigue life ( 8 cycles) as well as the initiation and growth of a dominant fatigue crack in the VHCF regime ( N f  = 0.82 × 10 9 cycles).