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

在室温~ 350℃范围内对SiC晶须增强铸造铝合金（SiC/AC8A）进行了疲劳试验，研究了疲劳裂纹的萌生和扩展行为。SiC/AC8A的室温疲劳强度优于铸铝合金AC8A。SiC/AC8A的室温10^7次疲劳强度约为AC8A的2倍。FRM的裂纹起裂循环次数约为AC8A的600倍，相当于总疲劳寿命的90%。FRM疲劳寿命的增加是由于裂纹萌生循环次数的增加。在350℃时，FRM的疲劳强度也比AC8A大，但增幅降至17%左右。FRM在350℃下100h的疲劳强度等于在350℃下0.5h的疲劳强度。对于FRM来说，温度升高次数没有明显的影响。

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.