Role of Ti3AlC2 MAX phase on characteristics of in-situ synthesized TiAl intermetallics. Part IV: mechanical properties

Abstract

In this study, the 4th part of a series of publications on the sintering and characterization of TiAl-Ti3AlC2 composite materials, the mechanical properties were measured and discussed. For this purpose, different contents of synthesized Ti3AlC2 reinforcement (10, 15, 20, 25, and 30 wt%) were added to metallic Ti and Al powders, then ball-milled and manufactured by spark plasma sintering (SPS) for 420 s at 900 ºC under 40 MPa. Flexural strength, fracture toughness and Vickers hardness were measured by 3-point technique, SENB method, and indentation technique, respectively. Increasing the Ti3AlC2 content resulted in improvement of the mechanical properties, so that TiAl-25 wt% Ti3AlC2 composite showed the best flexural strength and Vickers hardness (270 MPa and 4.11 GPa, respectively). Increasing amount of Ti3AlC additive had no significant effect on fracture toughness. Densification improvement, in-situ formation of Ti2AlC, and limitation of grain growth were recognized as the reasons of mechanical properties enhancement. In contrast, further addition of Ti3AlC2 (30 wt%) decreased the mechanical properties due to the reduction of density and formation of more Ti2AlC agglomerates in grain boundaries.