Modification of microstructure and properties of Ti-47Al-2Cr-4Nb-0.3W alloys fabricated by SPS with trace multilayer graphene addition

In this paper, Ti-47Al-2Cr-4Nb-0.3W alloys with trace multilayer graphene addition were fabricated by spark plasma sintering to enhance both mechanical properties and tribological property simultaneously. With the addition of multilayer graphene, bending strength, compressive strength and tribological property of TiAl alloys are all improved. When graphene content increases from zero to 0.8 at.%, the mean grain size decreases from 14.8 ± 1.4 μm to 8.2 ± 0.8 μm. The bending strength reaches almost 1000 MPa and the fracture strength increases to 2347 ± 12 MPa, an increase of 15% compared with TiAl alloy. The friction coefficient also decreases from about 0.6 to 0.4, a decrease by 1/3 compared with TiAl alloy. The reasons for the improved mechanical properties and tribological property are the in-situ reaction plate-shape Ti₂AlC phase, fine needle-like Ti₃AlC phase as well as fine and homogeneous microstructure. The wear mechanism changes from abrasive wear to abrasive wear plus adhesive wear with the increased graphene content.