2. Structural precipitation characteristics

2.1 Alloy composition criteria and heat treatment sequence

Consider an Al-M binary alloy (figure 2 a ). For it to be suitable for precipitation hardening, the alloying element in the solid-state aluminum matrix must exhibit increasing solubility with temperature. For simplicity's sake, we assume that there is a eutectic reaction for this alloy at temperature T _E for concentration x _E . The ratio of the mean slopes of liquidus and solidus, called the partition coefficient, is then less than 1. This is the most general case for structurally hardening aluminum alloys produced by conventional...