Effects of trace zirconium on the initiation and propagation behavior of fatigue cracks in Cu-6Ni-2Mn-2Sn-2Al alloy

The effects of trace Zr on the fatigue behavior of Cu-6Ni-2Mn-2Sn-2Al alloy were studied through the initiation and growth behavior of a major crack. When stress amplitude was less than σa = 350 MPa, the fatigue life of Zr-containing alloys was about 2 times larger than that of alloy without Zr. When σa = 400 MPa, the effects of Zr addition on fatigue life disappeared. Increased fatigue life due to Zr addition resulted from an increase in crack initiation life and microcrack growth life. Zr addition generated strengthened grain boundaries (GBs) that developed from the precipitation of SnZr compounds. Strengthened GBs contributed to the increase in crack initiation life. The effects of Zr addition on fatigue behavior were discussed with relation to the behavior of microcracks.