Excellent calcium–magnesium–aluminosilicate corrosion resistance of high‐entropy garnet/alumina directionally solidified eutectic at 1500°C

Abstract

AbstractHigh‐temperature corrosion resistance is one of the major challenges for hot‐section components in gas turbines. In this paper, the interaction of a novel high entropy (HE) (Y0.2Gd0.2Ho0.2Er0.2Yb0.2)3Al5O12/Al2O3 directionally solidified eutectic (DSE) with molten calcium–magnesium–aluminosilicate (CMAS) at 1500°C for 4 to 200 h was investigated and the results indicate that (Y0.2Gd0.2Ho0.2Er0.2Yb0.2)3Al5O12/Al2O3 DSE possesses excellent CMAS resistance, with a true recession depth about 219.5 μm after corroded by CMAS at 1500°C for 200 h. Moreover, possible explanations on the outstanding CMAS corrosion resistance, including the protective diffusion‐blocking garnet layer and the actively adjustment on the corrosion activity of CMAS melt by both the rapid dissolution of Al2O3 phase and the synergetic effects of multicomponent RE elements, are deduced based on the identification, distribution and evolution analysis of the reaction products over the corrosion time. The current results can cast light on new mechanisms and strategies with respect to multilevel optimization to develop new high‐temperature structural materials with enhanced CMAS corrosion resistance ability.