Strategies for hardening purity metallic materials by high pressure and high temperature quenching method.

Purity metallic materials are increasingly demanded in modern manufacturing industries, but their applications are limited owing to their poor wear resistance and mechanical properties. Therefore, exploring an efficient hardening method to significantly enhance the hardness of pure metals is emergent in materials science. In this work, a series of high pressure and high temperature (HPHT) quenching experiments were carried out on several pure metals, with a maximum hardening factor exceeding 10. The results indicated that pressure has an unusual effect on refining grains and increasing the Hall–Petch coefficient k_y. The k_y value of pure Fe is 49.5 GPa*μm^1/2 with a quenching pressure of 5 GPa, which is two orders higher than that of the untreated polycrystalline sample (0.2 GPa*μm^1/2). In addition, we report an extreme hardness of 8.34 GPa in pure Ti induced by HPHT quenching, and the unprecedented hardening comes from the formation of the twin and lath martensitic substructures. The hardening mechanism of the HPHT quenching method is a combination of Hall–Petch hardening and work-hardening. Our results provide a practical route to achieve attractive mechanical properties in pure metals and shine a light on the hardening mechanism of metallic materials. [ABSTRACT FROM AUTHOR]