High Temperature Cyclic Oxidation of Ni-based 800H Superalloy at 700°C in Air

Abstract

The high temperature cyclic oxidation has been investigated on 800H superalloy, composed of Fe-33Ni-19Cr alloy at 700? for 150 cycles in laboratory air. Two types of samples has been used, where the Fe-33Ni-19Cr alloy has been experienced a different heat treatment temperatures, which are 1000? and 1100?, which has differ grain size. The alloy was subjected to a short oxidation period at 700? for one hours, followed by cooling for 20 minutes for each cycle. The oxide phase analysis has been analyzed using x-ray diffraction (XRD) technique. The cross sectional line scan analysis has been examined using field emission scanning electron microscope (FESEM) equipped with energy dispersive x-ray (EDX) spectrometer. The phase analysis recorded four types of structure has formed on the oxidized sample, composes of austenite phase represent the base metal, corundum oxides, spinel oxides and fluorite oxides structure. The cross sectional analysis indicate that the oxidized samples were formed a several oxide layer, mainly compose of Cr-Mn and Cr-Ti rich oxide with detection of internal oxide precipitates compose of Al-oxide and Si-oxide precipitates.