IN-SITU FORMATION OF THE TI3AL-SIC METAL-MATRIX COMPOSITE SYSTEM FROMITS COMPONENTS

Ti3Al-SiC metal matrix composite (MMC) can be produced directly from i ts components by mechanical alloying and the use of hot isostatic pres sing (HIP) for consolidation. A composite containing 5% SiC produced b y this technique is of better quality than the unalloyed Ti3Al. The pr ogress of in-situ formation of Ti3Al during sintering or HIP from its constituents, with and without SiC, was analyzed by X-ray diffraction (XRD), with Cu K alpha radiation. Ti3Al or a composite produced on the basis of this compound can also be obtained by sintering of the mecha nically alloyed aggregate, but the composite so produced has low densi ty and low specific strength and in general it is inferior to the mono lithic base alloy itself. The poor quality is attributed to the format ion of an interaction zone at the interface of the fiber and Ti3Al. Th e evolution of the reaction zone was followed by optical microscopy. F rom 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).