High temperature tribological behavior of a Ti-46Al-2Cr-2Nb intermetallics

Tribological behavior of a Ti-46Al-2Cr-2Nb alloy, produced by hot-pressed sintering, was investigated using a home-built ball-on-disc tribotester against a Si3N4 ceramic ball at a constant speed of 0.188 m s(-1) and an applied load of 10 N from 20 to 900 degrees C It was found that the friction coefficient decreased slowly with increasing temperature from 20 to 600 degrees C, and then rose and reached the highest value at 800 degrees C, but slightly dropped at 900 degrees C. The wear rate of the alloy, in the magnitude of 10(-4) mm(3)/Nm, increased mildly with increasing temperature to a maximum value at 400 degrees C and then dropped rapidly from 600 to 800 degrees C and increased a little at 900 degrees C. The wear mechanism of the alloy transformed from mainly ploughing and small delamination wear at 20-700 degrees C to plastic deformation and adhesive wear at 800 and 900 degrees C. The transition of the wear mechanism occurred between 700 and 750 degrees C. The friction and wear behavior of the hot-pressed Ti-46Al-2Cr-2Nb alloy was comparable to that of a vacuum casting Ti-41.7Al-8.3Nb-0.09Y alloy measured under the same conditions for comparative purposes. (C) 2012 Elsevier Ltd. All rights reserved.