Mechanical behavior of a fiber reinforced Ni3Al matrix composite

Pressure casting has been used to reinforce a Ni₃Al-based alloy, IC218, with continuous Al₂O₃-based fibers, DuPont's 20 μm diameter PRD-166 fibers. The mechanical properties of the cast composites and the unreinforced IC218 were evaluated at room temperature and 1000°C, in air. Optical, transmission and scanning electron microscopy were employed to characterize the microstructure and fracture of the composites. Reinforcing IC218 with PRD-166 fibers resulted in an increase in elastic modulus and a reduction in strength. A high degree of fiber-fiber bonding is believed to be responsible for the observed reduction in strength. Residual stresses which resulted from the thermal expansion mismatch between the fiber and matrix were not sufficient to deform the matrix during cool-down from the processing temperatures.