Microstructure and tensile properties of mechanically alloyed Ti–6A1–4V with boron additions

Particulate titanium metal matrix composites (MMCs) offer advantages for a wide range of structural applications with increases in stiffness and possibly wear resistance. A powder metallurgy/mechanical alloy route was used successfully to give a fine, uniform distribution of boron in titanium alloy powder. This powder was hot isostatically pressed and during the process TiB reinforcement was formed by an in-situ reaction. Significant tensile ductility in MA titanium alloy (without boron), equivalent to wrought material was achieved, along with good tensile strength. In materials with high TiB volume fractions it is thought that the fine boride size and high strength matrix caused embrittlement. This suggests that the use of a lower strength matrix, such as commercial purity titanium, and shorter milling times would provide a better balance of strength, stiffness and ductility for this type of composite.