A novel wear-resistant Ni-based superalloy via high Cr-induced subsurface nanotwins and heterogeneous composite glaze layer at elevated temperatures

Abstract

Tribo-induced structural and chemical modifications at elevated temperatures play paramount roles in the tribological performance of Ni-based superalloys. Here, we report on a novel face-centered-cubic Ni-27Cr superalloy with a low stacking fault energy exhibiting remarkable tribological properties at 25–800 ℃, especially the low wear rates at 400 ℃ (1.97 ×10−5 mm3/N·m) and 800 ℃ (3.1 ×10−6 mm3/N·m). First, at 25–600 ℃, tribo-induced deformation nanotwins show superior structural stability, contributing to the high wear resistance. Second, at 800 ℃, the tribo-induced nanotwins are not formed. Instead, the topmost glaze layer transits from homogeneous nanostructure to heterogeneous microstructure consisting of hard nanograined oxides and soft ultrafine grained matrix. The strong and ductile heterogeneous composite glaze layer accommodates large plastic deformation and reduces wear loss.