Tribochemistry of dry-sliding wear of structural TiAl(Nb,Cr,Zr)B,La intermetallics family against the chromium steel

Effects of microstructure and composition on dry friction, wear and tribochemistry of worn surfaces of new intermetallics Ti–44Al–5Nb–3Cr–1.5Zr, Ti–44Al–5Nb–2Cr–1.5Zr–0.4B–0.07La and Ti–44Al–5Nb–1Cr–1.5Zr–1B–0.17La (at%) sliding against the steel 40Cr have been investigated in air. XRD, SEM, EDX and on-depth ion sputtering techniques were used to investigate the alloys, their worn surfaces and debris particles. For all three alloys the friction coefficient (f) increased vs. sliding way within the range of 0.16–0.39, afterwards followed by the steady state. Neither grain refinement degree, nor content of (Ti,Nb)B, La2O3 abrasives in intermetallics affected the stationary f value and wear rate. This tribological behavior reflects the kinetics of FeO-based cover formation on the worn surface, resulting from local oxidation of counterbody steel under the frictional heating-up. [Display omitted] •Tribometric testing of three new γ-TiAl based alloys against 40Cr steel.•Neither microstructure, nor content of TiB and La2O3 inclusions affected friction coefficient.•Clarification of thermo-mechanical oxidative mechanism of wear.•Alloyed steel undergoes the principal wear within the friction pair.•High wear proof of new intermetallic alloys.