FORMATION AND INTERFACE STRUCTURE OF TIC PARTICLES IN DISPERSION-STRENGTHENED CU ALLOYS

TiC-dispersion-strengthened Cu alloys were prepared by mechanical allo ying and subsequent hot extrusion. The evolution of the microstructure with respect to the preparation process is analysed by transmission e lectron microscopy techniques. The TiC dispersoids are formed in situ by the reaction of Ti and graphite. Ti diffuses from the pre-alloyed C uTi matrix to C inclusions which are embedded in the matrix after high -energy milling. Heat treatment of the powder mixtures at 400 degrees C leads to heterogeneous nucleation of TIC at the C/Cu interface. Ther eby a well defined cube-on-cube orientation relationship is establishe d between TiC and the Cu matrix. A study of the morphology of the TIC dispersoids shows that they are faceted on {111}(TiC), {110}(TiC) and {100}(TiC) planes and possess ledges on the atomic scale. The TiC/Cu i nterfaces are atomically abrupt and free of interface phases. The {100 }(TiC)//{100}(Cu) and [110](TiC)//[110](Cu) topotaxy leads to a misfit of 17.6% between the adjacent lattices. This misfit is accommodated b y a dislocation network along [100](Cu) directions.