Hundred years of precipitation hardening

Abstract

About 100 years ago, precipitation hardening was discovered and the first structural aluminum alloys with considerable strength were developed. Our present understanding of the phenomenon in based on the application of dislocation theory as well as reaction kinetics, especially the role of metastable phases and lattice defects in nucleation from supersaturated solids. The prerequisites for optimum precipitation hardening can be precisely defined. However, the progress in the development of new alloys has been slow in the recent years. The original alloy is still in use today.