FABRICATION AND IMPACT PROPERTY OF MULTI-SCALE TIB/TI6AL4V COMPOSITES BY POWDER METALLURGY

To improve impact toughness of TMCs, a kind of Ti6Al4V-TiBw/Ti6Al4V multi-scale titanium matrix composite has been successfully fabricated by preparation of powders, stacking, hot pressing and rolling. The microstructure morphology of sintered composite shows a laminated structure in low magnification and network microstructure in TiBw/Ti6Al4V layer, and the interface is well-bonded. The average grain size in TiBw/Ti6Al4V layer is finer than that in Ti alloy layer (9.25 mu m and17.66 mu m respectively), which is mainly because TiB whiskers can inhibit grain growth. Large degree of strain occurs around TiB whiskers and thus prompts dislocation concentration and strengthen TiBw/Ti6Al4V layer. Rolling can decrease thickness layer and after rolling, the laminated structure still exist while network structure is destroyed to some extent. The introduction of Ti alloy layer can increase impact energy compared with TiBw/Ti6Al4V composite, which is mainly because crack deflection and interface crack.