Precipitation Hardening in Aluminum

Heating and Quenching steel makes it stronger and more brittle, because of the way small Carbon atoms are trapped in the lattice of larger Iron atoms... this is an interstitial alloy. In Aluminum, however, the alloy atoms are much closer to being the same size as the Aluminum. This makes it a substitutional alloy, where the alloy atoms take the place of an Aluminum atom, rather than trying to fit into a void. As a result, the heat treatment process for Aluminum is almost the exact opposite of that for steel. This video looks specifically at 6061-T6 aluminum, and discusses both how to undo the T6 heat treatment... and get it back!