Superior hardness-corrosion-resistance combination in a Co-, Cu-modified Ni-Cr-Mo alloy via multiple nanoscale segregation mechanisms

Hardening of Ni-Cr-Mo corrosion-resistant alloys facilitates the expansion of their industrial applications; however, it remains challenging. Herein, we report significant hardening in a Co-, Cu-modified Ni-Cr-Mo alloy under appropriate cold swaging/aging conditions. Age-hardening occurred over a relatively short period ( '0.5 h) and became clear upon cold-swaging to an area reduction of >60%, exhibiting peak hard-ness at 50 0-60 0 degrees C. Exceptional hardness (HV599), unattainable in conventional Ni-Cr-Mo alloys, was obtained after aging. Scanning transmission electron microscopy revealed that multiple nanoscale segre-gation mechanisms, including Suzuki segregation at stacking faults and Cr-rich nanodomains within the severely cold-swaged face-centered cubic matrix, were responsible for the resultant hardening. Further-more, segregation of Cu, alongside Cr and Mo, along the deformation-induced boundaries induced a fine dispersion of nanoscale Cu precipitates throughout the matrix, imparting further hardening. A superior combination of hardness and corrosion performance was realized through this strategy. (c) 2021 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Automated summary

In this study, significant hardening was achieved in a Co-, Cu-modified Ni-Cr-Mo alloy under appropriate cold swaging/aging conditions, resulting in exceptional hardness (HV599) and improved corrosion performance through nanoscale segregation mechanisms and fine dispersion of Cu precipitates.