Mechanical Properties and Microstructure of PM Ti-Si3N4 Discontinuous Fibre Composite

2 vol% Si₃N₄ fiber Ti composites were manufactured by uniaxially pressing the powders and subjecting the green compact to pressureless sintering at 1400°C in flowing argon. The resulting composites were >98% theoretical density. The hardness of the titanium composite was measured at HBW 401 compared to HBW 293 for pure titanium. Microstructural analysis showed clearly defined 200–300nm diameter crystalline fibers throughout the composite with a 2–4μm reaction boundary cementing them to the titanium. Concentrations of smaller Si₃N₄ particles were located at the titanium grain boundaries, which may have reacted to form Ti-Si-N phases. The improved mechanical properties might be from a combination of discontinuous fiber reinforcement, nitrogen addition to the Ti matrix, and grain-boundary reinforcement.