High strength and large ductility in spray-deposited Al–Zn–Mg–Cu alloys

• Spray deposition process was used to produce Al alloys with excellent performance.
• The deposited alloys exhibited a high strength of 690 MPa and elongation up to 17.2%.
• The η′ phase was coherent with α-Al and their orientation relationship was studied.
• The interface misfits and the transition matrixes of two phases were calculated.

The mechanical properties and microstructure of large-scale Al–Zn–Mg–Cu alloys fabricated by spray deposition/rapid solidification technology were investigated in detail. The as-extruded alloys under peak-aging temper exhibited ultimate tensile strength (UTS), yield strength (YS) and elongation of 690 MPa, 638 MPa and 17.2%, respectively. The simultaneous coexisting of high strength and large tensile ductility of the alloys were achieved in our experiment. It was considered that the high-density nano-precipitates distributed uniformly in the peak-aged alloys may be responsible for the high strength and improved ductility. Orientation relationship between η′ precipitates and α-Al matrix were verified by high resolution transmission electron microscopy (HRTEM) and selected area electron diffraction patterns (SADPs) observations. The η′   phases in the alloy were fully coherent with the aluminum matrix, with the orientation relationship of (101¯0)η′//{110}Al and [1¯21¯0]η′//<1¯12>Al. The relationship between the lattice parameters of η  ′ phase and the related plane-spacing of the aluminum were aη′=3d(112)Al and cη′=6d(111)Al. Based on obtained orientation relationship, the transition matrix of η′ phases were also calculated.