Fatigue Crack Initiation and Propagation Behavior of Fiber Reinforced Metal (Sic/Al) at elevated temperatures

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Fatigue tests were made on a random SiC whisker reiforced cast aluminum alloy (SiC/AC8A) over the temperature range from room temperature to 350 C. Fatigue crack initiation and propagation behavior were investigated.The fatigue strength of SiC/AC8A is superior to that of cast aluminum alloy AC8A at room temperature. Fatigue strength at 10^7 cycles at room temperature of SiC/AC8A is about 2 times that of AC8A.The number of cycles for crack initiation of FRM is about 600 times that of AC8A, is equivalent to 90% of the total fatigue life. the increase in the fatigue lives of FRM is owing to the increase in the number of cycles for crack initiation.The fatigue strength at 350 C of FRM is also larger than that of AC8A, but the rate of increase of FRM decreases to about 17%. The fatigue strength for 100h at 350 C of FRM is equal to that for 0.5h at 350 C. For FRM, times at elevated temperature does not have a marked effect.