Enhancement of cyclic oxidation resistance and effect of transition oxides on wear mechanism of yttrium plus aluminium modified tribaloy T-900 alloy

•Commercial Tribaloy T-900 alloy was alloyed with aluminium and aluminium plus yttrium.•High temperature cyclic oxidation behaviour and wear mechanism were investigated in air.•Yttrium plus aluminium improved the cyclic oxidation resistance by forming compact and continuous external Al2O3 layer.•Al2O3 layer blocked the internal nitrides and oxides formation, which could be detrimental to mechanical properties.•Yttrium addition enhanced the adherence of transition oxides scale during sliding wear. This paper investigated the microstructure, cyclic oxidation behaviour and wear mechanism of modified and unmodified Tribaloy T-900. Yttrium and aluminium addition promoted the selective oxidation of Al, which reduced the oxidation rate by forming continuous protective layer of Al2O3 at 1000 °C. Al2O3 layer hindered the formation of simultaneous internal oxidation and nitridation zone. Yttrium addition transforms the mechanism of grooving wear to rolling wear by increasing the surface passivation and adherence of transition oxides scale during sliding wear. Hardness of T-900Al and T-900AlY was increased due to refinement of Laves phase and precipitation of grey intermetallic phase.