Development and oxidation resistance evaluation of Al-rich surface layer on Alloy 617

Abstract

Surface treatment was carried out for Alloy 617 to improve the high temperature oxidation resistance. After high purity Al was pre-deposited on the surface, electron beam (EB) was applied to form Al-rich micro-alloying zone with the depth of similar to 50 mu m. In the micro-alloying zone, cellular and dendritic structures with very fine arm spacing were developed. In the oxidation test performed in air at 900 degrees C up to 1000 h, a transient oxidation behavior was observed for the surface-treated Alloy 617. During the short initial oxidation stage (<1 h), Al-rich external oxide layers with the outermost spinel and inner alumina were quickly formed. However, during the steady-state oxidation stage, the oxidation rate of EB surface-treated Alloy 617 was substantially lower than that of the as-received Alloy 617. (C) 2013 Elsevier B.V. All rights reserved.