Surface Remelting‐Mediated Improvement in Oxidation Resistance of Cr2Nb‐Containing Nb‐Si‐Based Alloys at High Temperatures

Abstract

The poor oxidation resistance of Nb‐Si‐based alloys generally limits their high‐temperature application. A surface remelting strategy for the formation of protective oxide scales and the improvement of oxidation resistance is reported. Electron beam surface melting (EBSM) is performed on arc‐melted Nb‐14Si‐18Ti‐12Cr‐7Al‐0.2Y (at.%) alloys. The microstructure is significantly refined, without altering the phase regime that consists of an Nb solid solution, βNb5Si3 and Cr2Nb. After oxidation at 1200 °C, the EBSM‐remelted layer forms a flatter and more compact oxide scale without significant cracking or spalling than that on the arc‐melted alloy. A continuous SiO2 oxide layer is formed within the oxide scale on the EBSM‐remelted layer. A reduction of ≈47% in the oxide scale thickness, indicative of improved oxidation resistance, is achieved by the EBSM treatment. The present work provides a promising engineering approach toward the design and fabrication of Nb‐Si‐based alloys with balanced properties.