Abstract:We link different microstructures to tribological behaviors of Ti-50.8Ni (mole fraction, %) in reciprocating mode at room temperature (20 °C). Hot-rolled alloys with B2 phase exhibit lower coefficient of friction and wear rate compared to the ones with B19？. Stress-induced martensitic transformation occurs during sliding. However, multi-pass hot rolling weakens the wear resistance. In this study, microstructures were characterized through electron backscatter diffraction and transmission electron microscopy (EBSD/TEM). From the concept of energy conservation, the effects of weak intensity of hot-rolled textures on the wear resistance are minimal. Based on the result that the alloy with a higher portion of coincidence site lattice boundaries shows lower martensitic start transformation temperature in the DSC curves than that with higher KAM values, the delay on B2-B19？ transformation from {112}_B2 twins outweighs dislocations. Moreover, widely distributed small-angle grain boundaries owing to dynamic recovery improve the wear resistance effectively compared to those that are well-recrystallized.

Key words: Ti-50.8Ni alloy; tribological performance; small angle grain boundaries; coincidence site lattice (CSL) boundary