Effect of yttrium on the oxide scale adherence of pre-oxidized silicon-containing heat-resistant alloy

This paper investigates the effect of the rare earth element yttrium on the rupture behaviour of the oxide scale on the silicon-containing heat-resistant alloy during cooling. After 10 h of oxidation, yttrium is found to facilitate the formation of internal oxides (silica) at the scale–matrix interface. Due to the twinning observed by scanning transmission electron microscopy (STEM) in silica, the critical strain value for the scale failure can be dramatically improved, and the formation of cracks at the scale–matrix interface is inhibited.

► AE experiment shows yttrium has a beneficial effect on the pre-oxidized HP40 alloy.
► Yttrium facilitates the formation of internal oxide after 10 h of oxidation.
► Internal oxide changes the rupture behaviour of the oxide scale.
► Twins form in the internal oxide and improve the binding strength of the scale.