Correlation of Physical Parameters with Steady-State Hardness of Pure Metals Processed by High-Pressure Torsion

摘要

Pure metals of 30 elements with various crystal structures (bcc, fcc, hcp, diamond cubic, complex cubic, primitive hexagonal and tetragonal) are processed by high-pressure torsion (HPT) and their mechanical properties are subsequently evaluated by Vickers microhardness measurements. For all metals, the hardness reaches steady states at large strains where the hardness remains unchanged with further straining. It is shown that the hardness values at the steady state are characteristics of each metal and are successfully expressed as a unique function of the homologous temperature, shear modulus and physical parameters of metals such as melting temperature, specific heat capacity and diffusion coefficient except for a few elements. The findings are well applicable to predict the ultimate steady-state hardness of metals attained by HPT processing through the correlation established in this study.