The effect of hot-pressing temperature on the tensile strength of B4C coated boron fiber reinforced Al composites.

Abstract

For the purpose of investigating the effect of interfacial bonding between a fiber and a matrix on the tensile strength of FRM, several B4C coated boron fiber reinforced Al composites were prepared by controlling the hot-pressing temperature. The tensile-test showed that the composites prepared at 550°C exihibited a higher strength than the composites prepared at 500°C and 600°C. The fracture surfaces were changed from a rugged face like a bundle break to a flat face with an increase in the temperature. It was seen from SEM that the interfacial bonding became stronger. So, the transition in the composites' strength was considered as follows ; As the hot-pressing temperature rises, the critical fiber length, a factor determining a fiber's strength in a matrix, becomes gradually shorter, but the stress concentration factor to the adjacent fibers caused by a fiber fracture also becomes larger. Therefore, the higher strength of the composites results in the case that these two factors are properly overlapped. Such a transition of the composites' strength was additionally supported by Batdorf's theory.