Wear-resistant CoCrNi multi-principal element alloy at cryogenic temperature

Area of Science:

• Materials Science
• Tribology
• Cryogenic Engineering

Background:

• High-strength engineering alloys often exhibit surface brittleness and poor wear resistance at cryogenic temperatures.
• This limits their application in demanding cold environments.

Purpose of the Study:

• To investigate the cryogenic wear resistance of cobalt-chromium-nickel (CoCrNi) multi-principal element alloys.
• To elucidate the underlying temperature-dependent structural and deformation mechanisms responsible for enhanced wear performance.

Main Methods:

• Microscopic observation of worn surfaces and subsurface regions.
• Atomistic simulations to understand deformation mechanisms.
• Comparative analysis with cryogenic austenitic steels.

Main Results:

• CoCrNi alloys demonstrate significantly enhanced wear resistance as temperature decreases from 273 K to 153 K.
• Cryogenic conditions induce significant grain refinement and a deep plastic zone in the subsurface.
• Distinct deformation mechanisms, including stacking fault networks and phase transformation, contribute to strengthening and toughening.

Conclusions:

• CoCrNi alloys overcome the limitations of traditional alloys in cryogenic sliding contact.
• The unique subsurface microstructural gradient and deformation mechanisms are key to their superior cryogenic wear resistance.
• CoCrNi alloys are promising candidates for safety-critical applications in cryogenic environments.