Fabrication and characterization of TiAl/Ti3Al-based intermetallic composites (IMCs) reinforced with ceramic particles

Purpose: The purpose of the paper is to fabricate and characterise TiAl/Ti3Albased intermetallic composites (IMCs) reinforced with ceramic particles. Methodology: Composites were formulated by blending commercially available powders of either TiAl or Ti3Al (technical grade with traces of Al and Ti) with ceramic powders (B4C, TiC or TiB2) in appropriate amounts to create titanium aluminide-based matrices with 10, 20, 30, 40 and 50 vol. % of B4C, TiC or TiB2 discontinuous reinforcement. The powder blends were thoroughly mixed and subsequently cold compacted. Findings: Qualitative metallographic analysis of the as-densified microstructures confirmed that during densification of the composite matrix both TiAl and Ti3Al single phase titanium aluminide powders were transformed into various intermetallic phases (TiAl, Ti3Al and TiAl3). Regarding the room temperature tensile properties, excellent tensile strength, tensile yield strength and modulus were measured in all fully dense composite samples, irrespective of their phase composition and volume fraction of reinforcement. Research: Generally, the improvement of tensile strength, tensile yield strength and Young’s modulus was found to correlate with the increase in the amount of ceramic reinforcement in the matrix. However, quite the opposite behaviour was found regarding elongation, where the introduction of ceramic particles into the intermetallic matrix led in all specimens to a significant reduction of elasticity. Value: In all systems and compositions, fully dense composite samples (with a retained porosity less than 1 vol. %) were successfully obtained, revealing the significant industrial potential of this fabrication method.