Accelerated Corrosion of High Entropy Alloys under Tensile Stress

TL;DR

This study demonstrates that uniaxial tensile stress significantly accelerates corrosion in high entropy alloys by causing passivation layer breakdown and pit propagation, impacting their application in harsh environments.

Contribution

It introduces a novel experimental setup to quantify corrosion rates under tensile stress in high entropy alloys and identifies the mechanisms behind accelerated corrosion.

Findings

Corrosion current density increased by three orders of magnitude under stress.

Corrosion potential dropped by approximately 150 mV.

Surface passivation layer breakdown leads to rapid pit propagation.

Abstract

High entropy alloys are finding significant scientific interest due to their exotic microstructures and exceptional properties resulting thereof. These alloys have excellent corrosion resistance and may find broad range of applications from bio-implants, aerospace components and nuclear industry. A critical performance metric that determines the application worthiness of the alloys is the resilience of stressed structural members in a corrosive environment. This study reports the results from a novel experimental setup to quantify the corrosion rate under uniaxial tensile stress in a single phase fcc Al0.1CoCrFeNi high entropy alloy rods. Under a uniform uniaxial applied stress of 600 MPa, the corrosion current density was observed to increase by three orders of magnitude and ~150 mV drop in corrosion potential. The mechanism of accelerated corrosion is identified as surface passivation layer breakdown, pit initiation on un-passivated surface and rapid pit-propagation along the loading direction.