Microstructural and mechanical properties of dual Ti3A1C2 -Ti2AlC reinforced TiAl composites fabricated by reaction hot pressing

A new dual Ti3AlC2 -Ti2AlC/TiAl composite was in situ synthesized by hot-pressing sintering process at 900 degrees C for 2 h using Ti, Al, and Ti3AlC2 powders as the initial materials. The phases and microstructure of the products were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The influence of Ti3AlC2 content on the mechanical properties of the composites was studied in detail. The composites were composed of TiAl, Ti3Al, Ti3AlC2 and a small amount of Ti2AlC phases. Ti(2)AC phase was mainly produced by the decomposition reaction of Ti3AlC2. The composite with 5 wt% Ti3AlC2 additive exhibited better properties, and the Vickers hardness, three-point flexural strength and fracture toughness were 2.7 GPa, 316 MPa and 7.3 MPa m(1/2), respectively. The toughening of the composite was primarily attributed to crack deflection, transgranular and/or translamellar cracking, pull-out of the carbides reinforcements and cleavage, especially, the combination toughening of Ti3AlC2 and Ti2AlC. (C) 2014 Elsevier Ltd and Techna Group S.r.l. All rights reserved.