Microstructure evolution and mechanical properties of Al-Zn-Mg-Cu alloy reprocessed by spray-forming and heat treated at peak aged condition

Machining chips of the alloy AA7050 were reprocessed by spray forming followed by hot-extrusion and heat treatment. The spray-formed deposit presented a microstructure with hardening η′ precipitates within the matrix and equilibrium η precipitates at the grain boundaries, refined grains and low segregation of the main elements Zn, Cu and Mg. The final microstructure at peak aged condition is mainly composed by Guinier-Preston (GP) zones, η′ metastable, η equilibrium , Al3Zr dispersoids and the coarse Al7Cu2Fe intermetallic. A well-defined precipitation free zone along grain boundaries was not observed. Good mechanical properties were achieved.