Effect of Ge Contents on Oxidation Resistance of Ni‐15Cr‐5Al Alloy at 1000°C

Abstract

A Ni‐15Cr‐5Al‐6Ge alloy was prepared using powder metallurgy technology. The effect of Ge on the oxidation resistance of Ni‐Cr‐Al alloy at 1000°C was investigated. The results indicate that the addition of Ge reduces the oxidation rate of the alloy interface in the range of 0 to 6 wt.% Ge. When the Ge content reaches 6 wt.%, a continuous and dense oxide film forms on the surface of the matrix, imparting the alloy with the best oxidation resistance. The addition of Ge improves the selective oxidation of Al and inhibits the diffusion rate of Ni and Cr elements to the alloy surface, resulting in the formation of a single, uniform Al2O3 oxide film on the alloy surface with a thickness of approximately 1.45 micrometers. An appropriate amount of Ge (6 wt.%) reduces surface defects, while an excessive amount of Ge (8 wt.%) increases surface defects, thereby adversely affecting the oxidation resistance of the alloy.