High cycle fatigue response of in-situ Al-based composites containing TiB2 and Al2O3 submicron particles

Aluminum-based composites reinforced with in situ TiB2 and Al2O3 submicron particles were fabricated via reactive hot pressing of TiO2, Al, B or B2O3 powders. The high-cycle fatigue (HCF) behavior of such in situ composites at room temperature was investigated under stress-controlled conditions at different load ratios. The S-N curves were determined in fully reversed tension-compression loading. The microstructures and fracture surfaces of in situ composites were examined to reveal their fatigue failure mechanism. The composite prepared from the Al-TiO2-B system and reinforced with TiB2 and Al2O3 submicron particles exhibited superior fatigue endurance stress and life. However, the composite fabricated from the Al-TiO2-B2O3 system had lower HCF resistance due to the formation of large intermetallic Al3Ti blocks. The fatigue response characteristics of both in situ composites are discussed in terms of the intrinsic microstructural and extrinsic stress ratio effects.