Investigation On Microstructure And Properties Of Ti₂AlC/TiAl Composite Prepared By Ma And SPS

TiAl based alloys are widely studied because they possess light weight, high specific strength and resistance to creep and oxidation. However, their application is currently limited by the low ductility and poor workability at room temperature. And it has been reported that TiAl based composite synthesized can be a better way to improve mechanical properties. Therefore, a new technology, which consists of mechanical alloying and spark pulse sintering, has been put forward to fabricate Ti2AlC/TiAl composite in order to receive ameliorated properties.The researched results showed that when the amount of PCA added into vial increased, Ti,Al powders would get finer and finer, composition of as-milled powders was close to the nominal ingredient, and powder yield was enhanced. At a high ball-to-powder weight ratio, because of an increased in the weight proportion of the balls, the number of collisions per unit time increased and consequently more energy was transferred to the powder particles and so alloying took place faster, powder yield was reduced and amount of impurities that got into the powder increased. With prolonging milling time, the Ti reacted with Al, through a mechaochemical reaction, to form orderly TiAl3,TiAl,Ti3Al intermetallics phase and amorphous phase, with continued milling, the amorphous phase can transform into TiAl3,TiAl,Ti3Al intertellics phase agaign. According to research results, it was decided that the initial amount of acetone (PCA) added to the vial was 1ml per 10g as-milled powders, the ball-to-powder ratio was 20∶1 and milling time was 50h, during mechanical alloying.Two kinds of bulk material obtained by SPS, one was Ti2AlC/TiAl prepared by as-sintered powder contained 2wt% CNTS addition, and Ti2AlC phase showed three-dimesional network, the other wasγ-TiAl based alloy exhibited a duplex structure consisting of theα2-Ti3Al andγ-TiAl phase, which was only prepared by as-sintered powder without any additions. Milling temperature has strong effect on the density of as-sintered bulk materials. as milling temperature raising,...