In-situ formation of the Ti 3AlSiC metal matrix composite system from its components

Abstract

Ti 3AlSiC metal matrix composite (MMC) can be produced directly from its components by mechanical alloying and the use of hot isostatic pressing (HIP) for consolidation. A composite containing 5% SiC produced by this technique is of better quality than the unalloyed Ti 3Al. The progress of in-situ formation of Ti 3Al during sintering or HIP from its constituents, with and without SiC, was analyzed by X-ray diffraction (XRD), with Cu Kα radiation. Ti 3Al or a composite produced on the basis of this compound can also be obtained by sintering of the mechanically alloyed aggregate, but the composite so produced has low density and low specific strength and in general it is inferior to the monolithic base alloy itself. The poor quality is attributed to the formation of an interaction zone at the interface of the fiber and Ti 3Al. The evolution of the reaction zone was followed by optical microscopy. From measuring the interaction zone width it appears that the kinetics of the interface reaction proceeds by a parabolic law with an apparent activation energy of 75 kJ mole −1.