In situ processing of Al-TiB2 composite by the stir-casting technique

Al base composite reinforced by in situ TiB2 particulates was successfully synthesized by the stir-casting technique. The composite, with a particulate size of 1-3 mu m, was produced by optimizing the process variables. An improvement of up to 61% in tensile strength 58% in yield strength and 23% in modulus, depending upon the volume fraction of TiB2 incorporated into the Al, was achieved. Modification of the Al matrix with the addition of copper improved the mechanical properties by a factor of not less than 2.5. Fractographs showed a dimpled fracture surface, indicating a retention of relatively high ductility not withstanding the presence of coarse TiAl3 associated with the Al-Ti-B system. The exhibition of a clean Al-TiB2 interface testified to the benefit that had been gained from the in situ processing. (C) 1999 Elsevier Science S.A. All rights reserved.