MORPHOLOGIES OF (Al,Ag)_3Ti AND Ti_3AlC PRECIPITATES IN Ll_0-TiAl INTERMETALLIC COMPOUND
TiAl金属间化合物中（Al,Ag）3Ti,Ti3AlC的析出形态

A trasmission electron microscopy (TEM) investigation has been performed on the moerphologies of Ll2-(Al,Ag),Ti and Ti3AIC precipitates in Ll0-ordered TiAl(Ag). During aging at temperatures around 1073 K after quenching from 1473 K, TiAl(Ag) hardens by the precipitation of (Al,Ag)3Ti and Ti3AIC. TEM observations revealed that plate-like precipitates (Al,Ag)3Ti lie on (001) plane of TiAl(Ag) matrix and needle--like pricipitates Ti3AlC, which lie only in one direction parallel to the 001] axis of the TiAl(Ag) matrix, appear after longer period aging or higher temperature aging. The anisotropic misfits between TiAl matrix and Ll2-(Al,Ag)3Ti and Ti3AIC can be considered to explain the morphologies of (Ag,Al)3Ti and Ti3AIC precipitates.