Strain Gradient Plasticity in Multiprincipal Element Alloys

The strain gradient plasticity of multiprincipal element alloys, CoCrNi and CoCrFeMnNi, was investigated in work-hardened and annealed conditions using nano-indentation. The hardness of the alloys demonstrated significant dependence on indentation depth, which was explained by geometrically necessary dislocations resulting from the high strain gradients due to the shape of the indenter. The characteristic length-scale of the indentation size effect for the multiprincipal element alloys was found to be larger than pure nickel due to higher friction stress, which constrains the storage volume of geometrically necessary dislocations.