Effect of reinforcement size on the elevated-temperature tensile properties and low-cycle fatigue behavior of particulate SiC/Al composites

The cyclic stress response characteristics and low-cycle fatigue endurance of powder-metallurgy-processed commercially pure aluminum composites reinforced with SiC particles of different sizes and of the unreinforced matrix were studied under a range of cyclic plastic strains at 441 K. Tensile properties of these materials were also examined. At elevated temperature the composites and unreinforced aluminum all definitely show cyclic softening. Under the same plastic strain amplitudes, the cyclic response stresses of the composites are higher than that of their unreinforced counterpart. Reinforcing particle size has no apparent influence on the cyclic stress/strain features of the composites The amount of cyclic softening is similar except that the cyclic response stress is slightly higher for the composite reinforced with small particles than for the large-particle-reinforced composite at a given cyclic strain amplitude. At high plastic strain ranges, the two composites display shorter fatigue lives than the unreinforced matrix material and of the two composites, the large-particle-reinforced composite exhibits slightly superior fatigue resistance. (C) 1997 Elsevier Science Limited.