Influence of SiC particulate size on the microstructural evolution and mechanical properties of Al-6Ti-6Nb matrix composites

Three kinds of SiC particulates (SiCp), whose diameters range from millimet er through micrometer to nanometer (designated as m-SiCp, mu-SiCp and n-SiC p, respectively), were separately incorporated into an Al-6wt.%Ti-6wt.%Nb a lloy by high energy ball milling. The as-milled composite particles are app reciably refined particularly when finer SiC particulate was added, and so do the in situ formed Al3Ti, AlNb2 dispersoids as well as the Nb particles. The room temperature strength and ductility of the composites, except for the stiffness, deteriorate unexpectedly. Nonetheless, elevated temperature strength and thermal stability of the composites are improved and greater s trength over that of the A1-6Ti-6Nb matrix alloy is exhibited above 240 deg rees C. The changes of the mechanical properties from room to elevated temp erature are correlated with the microstructure and fractographs. (C) 2000 P ublished by Elsevier Science S.A.