Determination of residual stress in alumina scale by photostimulated Cr3+ luminescence piezospectroscopy

Residual stresses in the scales of water-quenched and air-cooled Pt84:Al11:Cr3:Ru2 (at.%) specimens oxidized in air at 1150 °C for up to 100 h were measured using luminescence piezospectroscopy. Scanning electron microscopy equipped with energy dispersive spectroscopy, optical microscopy, X-ray diffraction and Raman spectroscopy showed that well-adhering, irregular and protective external α-Al2O3 scales developed on all specimens. Room-temperature residual stresses were compressive and became independent of oxidation times above 10 h exposure. Stress measurement results suggest that the air-cooled specimens possessed better adhesion than the water-quenched specimens, while both displayed lower stress values than those of the Ni- and Fe-based superalloys.

► We examine two alloys having similar compositions but quenched in different media.
► Oxidation at high temperatures results in formation of scales with residual stresses.
► The residual stresses were found to be compressive.
► Current alloy displayed lower stresses compared to other alumina forming alloys.