How calcium prevents precipitation hardening in Al–Mg–Si alloys

Precipitation Hardening of Metal Alloys

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 [1,2]. Duralumin is an aluminum alloy containing copper and magnesium with small amounts of iron and silicon. In a...

Precipitation hardening in dilute Al–Zr alloys

The aim of this study was to investigate the effect of solute content (hipoperitectic Al–0.22 wt.%Zr and hiperperitectic Al–0.32 wt.%Zr) on the precipitation hardening and microstructural evolution of dilute Al–Zr alloys isothermally aged. The materials were conventionally cast in a muffle furnace, solidified in a water-cooled Cu mold and subsequently heat-treated at the temperature of 650 K (3...

Precipitation Hardening of Al–Si–Mg Alloys

Modelling of Precipitation Hardening in Casting Aluminium Alloys

Precipitation hardening, because it involves the hardening of the material over a prolonged time, is also called age hardening, or ageing. By the appropriate heat treatment of precipitation hardening, the strength or hardness of some heat-treatable aluminium alloys can be enhanced by the formation of nano-meter sized second-phase precipitated particles within the original phase matrix. The fine...

Atomic pillar-based nanoprecipitates strengthen AlMgSi alloys.

Atomic-resolution electron microscopy reveals that pillarlike silicon double columns exist in the hardening nanoprecipitates of AlMgSi alloys, which vary in structure and composition. Upon annealing, the Si2 pillars provide the skeleton for the nanoparticles to evolve in composition, structure, and morphology. We show that they begin as tiny nuclei with a composition close to Mg2Si2Al7 and a mi...