Preparation And Characterisation Of Ti-6-4 And Ti-8-1-1 MMCs With High Specific Stiffness Using Powder Hot Extrusion And Arc-Remelting

Titanium alloys with high stiffness are crucial for aerospace engineering and are often fabricated using additive manufacturing methods like arc or laser techniques. These high energy processes alter the microstructure and mechanical properties. To enhance stiffness, TiC and B4C have been added to Ti-6Al-4V and Ti-8Al-1Mo-1V alloys via powder hot extrusion. The resulting metal matrix composites (MMCs) were analyzed in both their as-extruded and heat-treated states for microstructure and mechanical properties. To simulate an additive manufacturing process, samples were remelted using a gas tungsten arc welding (GTAW) torch and examined. Results showed 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 proved effective in producing Ti-MMCs with high stiffness even with reactive ceramic additions. However, GTAW remelting led to the decomposition of TiC-reinforced Ti-MMCs, significantly altering morphology and reducing stiffness below that of the base alloy.