抄録
Smooth specimens of an aluminum alloy 2024-T6 reinforced with 20 volume percent of silicon carbide particles (SiCp) were fatigued under four-point bending. The X-ray diffraction method was applied to measure the loading and residual stresses in each constituent phase. The phase stresses were determined from the diffractions of Al 222 and SiC 116. The compressive residual stress in the aluminum alloy phase increased with increasing stress cycles. For the SiC phase, when the ratio of the number of stress cycles to fatigue life, N/N_f, was larger than about 0.15, the compressive residual stress increased with stress cycles. Difference between the phase stresses measured at the maximum and zero loads was examined during fatigue. When N/N_f was larger than about 0.15, the change of the phase stress of both aluminum alloy and SiC particles decreased with the number of stress cycles. A lot of cracks in the matrix and decohesions at the interface were observed on the specimen surface. The decrease of the phase stress was caused by the initiation and propagation of fatigue cracks. The fatigue damage was successfully evaluated by the X-ray method.
