Tribological investigation of new self-fluxing nickel alloys for high temperature application: The effect of silicon distribution on glaze layer formation

The objective of this study is to investigate the tribological performance of new nickel-based self-fluxing alloys for replacing cobalt-based alloys in aircraft components. Two new NiCrSiFeB alloys, manufactured by gravity casting and laser metal deposition processes, having different microstructures, are submitted to fretting loadings and tested at temperatures ranging from ambient to 650 °C. Their wear behavior is compared to a reference Stellite 6 cobalt- based alloy. Although the two NiCrSiFeB alloys have the same chemical composition, the alloy having a coarse microstructure rich in silicates was able to form a protective glaze layer at high temperature as Stellite 6. On the other hand, the alloy having a fine microstructure underwent severe adhesive wear. This highlights the crucial effect of the microstructure and the silicon distribution in activating the formation of a protective glaze layer at high temperatures. • New NiCrSiFeB alloys are tested from ambient to 650°C under fretting loadings • Fine microstructure NiCrSiFeB alloy experiences severe adhesive wear • Coarse silicate-rich microstructure alloy forms protective glaze layer at 650°C • Microstructure and silicon distribution are key factors for glaze layer formation