Hydrogen embrittlement micromechanisms and direct observations of hydrogen transportation by dislocations during deformation in a carbon-doped medium entropy alloy

Abstract

The hydrogen embrittlement micromechanisms and the effect of carbon interstitial on hydrogen distribution were characterized in Fe40Mn40Ni10Cr10 and Fe38Mn41Ni10Cr10C1 medium entropy alloy. Ex-situ microstructural observations revealed that the segregation of carbon on grain boundaries suppresses hydrogen from being trapped in the grain boundaries for carbon-doped alloy before deformation. However, the distribution of hydrogen was similar for both alloys after plastic strain so that the grain boundaries trapped a large fraction of hydrogen during deformation. The fully intergranular fracture mode in the hydrogen affected area of both alloys was explained by the synergy of grain boundary–dislocation reactions and hydrogen-enhanced grain boundary decohesion effects.

Keywords

• Hydrogen embrittlement
• Medium entropy alloy
• Carbon segregation
• Hydrogen accumulation
• Hydrogen-enhanced decohesion
• Hydrogen-enhanced localized plasticity