Abstract
The present authors have reported on microstructures of unidirectionally solidified Al-CuAl2-Si, Al-CuAl2-NiCu3Al6, Al-CuAl2-FeCu2Al7 ternary eutectic composites in the preceding paper. In the present study, mechanical properties, fracture mechanics and thermal stabilities of these alloys were studied.
Although these ternary eutectic composites are reinforced with two kind of phases, the stress-strain curves consist of two zones, primary and secondary elastic zones, as have been observed in binary eutectic composites. Fracture of the composites occurred by the failure of one of the phases. Therefore, for estimating the tensile strength of the ternary eutectic composites from the law of mixture, we should consider the fracture strain of the two reinforcing phases. Solution treatment and aging of these composites are effective to improve their mechanical properties and fracture behaviour. Thermal stability of the ternary eutectic composites is greatly improved as compared with those of the concomitant binary eutectic composites, because the coarsening of the phases is interrupted mutually the phases.
