The wear behavior of powder metallurgy γ -tial alloy Ti-45Al-5Nb-0.4W+2Nb (atomic percentage) containing niobium particles has been investigated by pin-disk wear tests at room temperature. Dry slide wear tests were performed on zirconia discs in different environments: argon, hydrogen with nitrogen mixture, air and oxygen. The wear rate of TiAl pins increases significantly in the presence of oxygen, but is little affected by water vapor or molecular hydrogen. The wear surfaces and wear fragments of TiAl pins were examined by scanning electron microscopy and X-ray diffractometry. The friction layer in the Nb rich region near the wear tip of the pin was studied by transmission electron microscopy on the samples prepared by focusing ion beam milling. The results show that the residual Nb particles in β phase and the new compounds precipitated in the niobium-rich region around Nb particles improve the wear resistance significantly. During the wear test, the zirconia discs underwent a phase transition caused by high stress and temperature. The abrasive particles generated during wear testing were mainly composed of zirconia particles and were found to be embedded in the friction layer of the TiAl needle wear tip. The results show that the main wear mechanisms of (Ti-45Al-5Nb-0.4W)+2Nb alloy are two-body and three-body abrasive wear, partial delamination and plastic deformation. During the wear test, the zirconia discs underwent a phase transition caused by high stress and temperature. The abrasive particles generated during wear testing were mainly composed of zirconia particles and were found to be embedded in the friction layer of the TiAl needle wear tip. The results show that the main wear mechanisms of (Ti-45Al-5Nb-0.4W)+2Nb alloy are two-body and three-body abrasive wear, partial delamination and plastic deformation. During the wear test, the zirconia discs underwent a phase transition caused by high stress and temperature. The abrasive particles generated during wear testing were mainly composed of zirconia particles and were found to be embedded in the friction layer of the TiAl needle wear tip. The results show that the main wear mechanisms of (Ti-45Al-5Nb-0.4W)+2Nb alloy are two-body and three-body abrasive wear, partial delamination and plastic deformation.
In this work, the fretting wear behavior of Ti6Al4V titanium alloy and the tribological oxidation of thermal oxide film under different working atmosphere were studied by in-situ XPS analysis and testing combined with a self-designed high-precision fretting wear tester. The frictional oxidation (4×10-3Pa) environment caused by fretting in air and vacuum was analyzed, and its response to the resulting fretting wear resistance and damage mechanism was discussed. The results show that the working environment plays an important role in the formation of tribological oxidation and the determination of fretting wear properties. For all the fretting states, the thermal oxide film in vacuum atmosphere shows better fretting wear than that in air atmosphere, except for the partial sliding state (PSR), which has equivalent fretting wear. Compared with the matrix Ti6Al4V titanium alloy, the thermal oxide film in vacuum atmosphere has a good protection effect on the titanium alloy, especially on the slip state (SR), but it is not suitable for air atmosphere.
