Materials Science Forum, Vol.426-4, 1757-1762, 2003
Effects of processing condition on properties of Ti-aluminides reinforced Ti matrix composites synthesized by pulsed current hot pressing (PCHP)
Ti-aluminides reinforced Ti matrix composites were fabricated from 0.04mm-thcik Ti foils with 0.012mm- and 0.024mm-thick aluminum foils,. using pulsed current hot pressing (PCBP) process, and the effect of holding temperature on the properties of the composites was investigated. The microstructure of the composites fabricated was an alternatively laminated structure composed of Ti and reacted zones consisting of Ti-aluminides, and the reacted zones had different Ti-aluminides when PCBP-fabricated at different holding temperatures. Tensile tests carried out for the composites at room temperature revealed that the holding temperature is effective changing the mechanical properties (yield stress, elongation and fracture mode) of the composites. The tensile strength and the elongation of the composite produced at 1273K from 0.04-mm-thick Ti and 0.012-mm-thick Al foils showed 810MPa and 3,64%, respectively, while they are 677MPa and 3.44% for composite produced at 1173K. Microstructural observations of fractured specimens showed that the Ti layers effectively bridged numerous cracks formed in the Ti-aluminides in the composites fabricated at 1173 and 1273K. Large elongation was attributed to the bridge structure of many cracks of the Ti-aluminides in the composites, which were fabricated at temperatures lower than 1273K.
Keywords:titanium;titanium-aluminide;intermetallic compound;metal-matrix-composite;combustion synthesis;spark plasma sintering;pulsed current hot pressing