Precipitation hardening in metals

TLDR

Precipitation hardening has long been employed to strengthen commercial alloys such as quenched‑and‑tempered steels and duralumin aluminium alloys, and its theoretical treatments are briefly reviewed. The authors present equations describing strengthening by hard, indeformable particles and by soft, deformable particles, and discuss the resulting implications. They identify an optimum particle size that varies between systems, show that strength gains from precipitation largely depend on the volume fraction of precipitates, and compare these increments with theoretical predictions.

Abstract

AbstractAbstractPrecipitation hardening has long been used to increase the strength of commercial alloys, such as quenched and tempered steels and the duralumin type aluminium alloys. The theoretical treatments of precipitation hardening are briefly considered. The equations for strengthening by ‘hard’ indeformable particles and by ‘soft’ deformable particles are presented, and the implications are discussed. These lead to the concept of an optimum particle size for a given system, but the optimum can vary from system to system depending upon the particle characteristics. A broad comparison is made between the increments in strength that occur due to precipitation in commercial alloys and the predictions of the theories; an important contribution to these increments in strength is shown to derive from variations in the volume fraction of precipitated particles that can be employed in the various systems.