Preparation and characterisation of Ti‐6‐4 and Ti‐8‐1‐1 metal matrix composites with high specific stiffness using powder hot extrusion and arc‐remelting

Abstract

Titanium alloys with high stiffness are crucial for aerospace engineering and are often fabricated using additive manufacturing (AM) methods like arc or laser techniques. These high energy processes alter the microstructure and mechanical properties. To enhance stiffness, TiC and B4C are added to Ti–6Al–4V and Ti–8Al–1Mo–1V alloys via powder hot extrusion. The resulting metal matrix composites (MMCs) are analyzed in both their as-extruded and heat-treated states for microstructure and mechanical properties. To simulate an AM process, samples are remelted using a gas tungsten arc-welding (GTAW) torch and examined. In the results, it is shown that TiC and B4C increased mechanical properties up to 2 GPa cm3 g−1, with the highest increase observed in heat-treated B4C samples, achieving specific stiffnesses of 34.6 GPa cm3 g−1 (Ti–6Al–4V) and 32.3 GPa cm3 g−1 (Ti–8Al–1Mo–1V). Powder hot extrusion proves effective in producing Ti–MMCs with high stiffness even with reactive ceramic additions. However, GTAW remelting leads to the decomposition of TiC-reinforced Ti–MMCs, significantly altering morphology and reducing stiffness below that of the base alloy.