High cycle fatigue characterization of two die-cast magnesium alloys

High cycle fatigue characteristics of two magnesium alloys including die-cast AZ91D and AZ91D with 1%Ce(wt.%) addition were investigated. High cycle fatigue tests were carried out at a stress ratio(R) of 0.1 and a frequency of 90 Hz using cylindrical specimens at different maximum applied stress levels. Fatigue crack growth tests were conducted at R = 0.1 and a frequency of 20 Hz using single edge V-notched plate specimens. The results showed that some new rod-like Al11Ce3 phases were observed, and the elongation, yield and tensile strength of the materials are significantly improved in AZ91D alloy with 1%Ce(wt.%) addition. Die-cast AZ91D magnesium alloy with 1%Ce(wt.%) addition exhibits higher fatigue performance. The superior fatigue behavior of the alloy containing 1%Ce(wt.%) is mostly due to the grain refinement, Al11Ce3 and fined β phases at the grain boundary diffusely and cast characteristics improvement. The fractographs of two die-cast magnesium alloys shows basically quasi-cleavage fracture.