Fabrication, mechanical properties, and tribological behaviors of Ti₂AlC and Ti₂AlSn_0.2C solid solutions

Highly pure and dense Ti₂AlC and Ti₂AlSn_0.2C bulks were prepared by hot pressing with molar ratios of 1:1.1:0.9 and 1:0.9:0.2:0.85, respectively, at 1450 ℃ for 30 min with 28 MPa in Ar atmosphere. The phase compositions were investigated by X-ray diffraction (XRD); the surface morphology and topography of the crystal grains were also analyzed by scanning electron microscopy (SEM). The flexural strengths of Ti₂AlC and Ti₂AlSn_0.2C have been measured as 430 and 410 MPa, respectively. Both Vickers hardness decreased slowly as the load increased. The tribological behavior was investigated by dry sliding a low-carbon steel under normal load of 20-80 N and sliding speed of 10-30 m/s. Ti₂AlC bulk has a friction coefficient of 0.3-0.45 and a wear rate of (1.64-2.97)×10^-6 mm³/(N·m), while Ti₂AlSn_0.2C bulk has a friction coefficient of 0.25-0.35 and a wear rate of (2.5-4.31)×10^-6 mm³/(N·m). The influences of Sn incorporation on the microstructure and properties of Ti₂AlC have also been discussed.