抄録
Ductile fracture process in a titanium alloy composite reinforced with whisker-like TiB particles was investigated with particular reference to the effect of stress triaxiality. The materials investigated are TiB/Ti-8Al-0.5Mo-0.5V composite produced by vacuum arc remelting process and Ti-6Al-4V alloy for comparison. The in-situ reaction process provided strong interface between the matrix and TiB particles. TiB particles of 8% volume fraction raised significantly elastic modulus and tensile strength, while ductility was reduced. Degradation in ductility due to the stress triaxiality was more significant in TiB/Ti-8Al-0.5Mo-0.5V composite than Ti-6Al-4V alloy. Micro-voids in the composite were nucleated from the cracking of TiB particles at or beyond the plastic yielding of matrix irrespective of the state of stress triaxiality. They grew abruptly under a high stress triaxiality in the notched specimens. Fractographic observation demonstrated well the effect of stress triaxiality on micro-void coalescence type-ductile fracture.
