Voids Formed During Solution Heat Treatment of Aluminum

Solution treatment of aluminum is a critical first step in preparing an alloy for age hardening. The main purpose of solution treatment is to dissolve critical alloying components that strengthen the alloy and thus create a solid solution. A typical solution heat treatment requires that the alloy be heated above the solvus temperature, or to a temperature high enough to dissolve some of the constituent particles. Improper control of the furnace or excessive heating rates can produce voids in the aluminum that may reduce tensile ductility, fracture toughness and fatigue life. Exceeding the recommended solution temperature may cause incipient melting and also produce voids in the metal. Unlike incipient melting, these voids are only associated with the magnesium-rich constituent particles