ABSTRACT
Precipitation hardening, or age hardening, provides one of the most widely used mechanisms for the strengthening of metal alloys. The fundamental understanding and basis for this technique was established in early work at the U. S. Bureau of Standards on an alloy known as Duralumin. Duralumin is an aluminum alloy containing copper and magnesium with small amounts of iron and silicon. When age hardening of aluminum was discovered accidentally by A. Wilm, during the years 1903–1911, it quickly became an important commercial alloy under the trade name Duralumin. Paul Dyer Merica et al. suggested that examination of the relevant phase diagrams would reveal which alloys were candidates for precipitation hardening and would provide both the solutionizing temperature and the range of temperature needed for the precipitation process. This prescription proved to be astonishingly successful for developing new alloys.
