Oxidation Behavior of Al-Y Coating on γ-TiAl at 900 °C

Résumé

In this study, an Al-Y coating was applied to enhance the property of oxidation resistance on the surface of γ-
TiAl alloys by rf magnetron sputtering. The isothermal oxidation tests were investigated at 900 °C for 100 h.
The coating characteristics and microstructure of coating after isothermal oxidation were inspected by XRD
and SEM methods respectively, and coating bonding strength was investigated by scratch tester. Results
show that Al2O3 and Y2O3 were produced on the surface of γ-TiAl alloys to enhance oxidation resistance
during the isothermal oxidation test. Diffusion layer with rich element of Al provides abundant Al to surface
for formation of a continuous Al2O3 layer which increases oxidation resistance effectively. Oxides of YAlO3
and YAG were formed during the oxidation tests, which were beneficial for the strength, hardness and
fracture toughness of crystal grain of Al2O3. Furthermore, Element of Ti diffused into surface from substrate
was restrained by Al because of the formation of TiAl3 and TiAl, which avoid the layer-broken by titanium
oxides with porous structure
Keywords: Oxidation behavior; Magnetron sputtering; High temperature; Al-Y coating; γ-TiAl alloy;
Diffusion