Shear Stress in High-Pressure Torsion and Vickers Hardness of Au-Co Alloys

Alloys of the Au-Co system characterized by restricted solubility of the constituents were produced by shear deformation under high quasi-hydrostatic pressure. Resistance to shear strain was recorded during mechanical fusion. The forming pressure dependence of shear stress during deformation has been revealed, with the form of the curve remaining qualitatively unchanged. The form of the curve for the joint deformation of the Au-Co constituents differs from the curve recorded during the deformation of one constituent, namely gold. In the former case there are stages of sharp increase, retardation, and attainment of saturation, whereas in the latter case there is a sharp increase followed by attainment of saturation. This indicates the appearance of the deformation interaction of the constituents, which manifests itself in a prolonged increase in shear stress with an increase in strain, as distinct from the case of a single element, where there occur only structural changes caused by torsion under pressure. After the samples had been made, their Vickers hardness was measured, which demonstrates practically equal values of the hardness of the Au-Co alloys produced under different pressures.