CYCLIC STRAIN RESISTANCE OF A SPRAY-ATOMIZED AND SPRAY-DEPOSITED CAST-ALUMINUM-ALLOY METAL-MATRIX COMPOSITE

In this paper, the cyclic strain resistance and fracture behavior of a spray-atomized and -deposited cast-aluminum-alloy metal-matrix composite is examined. Test specimens of the Al/SiC(p) composite were strained to failure, under total strain-amplitude control, over a range of cyclic strain amplitudes giving less than 10(4) cycles to failure, for both the spray-processed and -cast microstructures. The spray-processed and conventionally cast composites followed the Coffin-Manson and Basquin relationships for variation of cyclic strain amplitude with reversals to low-cycle fatigue life. At equivalent plastic strain amplitudes the spray-processed material exhibited several orders of magnitude improvement in cyclic strain controlled fatigue resistance over the case composite counterpart. The rational for enhanced cyclic fatigue resistance is discussed in light of processing influences on composite microstructure, plastic-strain amplitude, concomitant response stress and macroscopic aspects of fracture.