Universal Plot for Hardness Variation in Pure Metals Processed by High-Pressure Torsion

Abstract

Various pure metals (Al, Au, Ag, Cu, V, Pt, Ni, Fe, Co, Ti, Zr, Hf, Mo) including Cu-30%Zn are processed by high-pressure torsion. Most of Vickers microhardness (HV) values are expressed by a universal plot when they are normalized as (HV⁄G)(T⁄T_m) and plotted against εP⁄G, where G, T⁄T_m, ε and P are the shear modulus, homologous temperature, equivalent strain and pressure, respectively. Deviations to this plot are for Al (99.99%), Ti, Zr, Hf and Cu-30%Zn and for when P is below a critical pressure.