Effects of minor Zr additions on the microstructure and mechanical properties of super-high strength Al alloys by spray forming were investigated by optical microscope（OM）

scanning electron microscope（SEM） and transmission electron microscopy（TEM）.The results show that there exists coarse non-dissolve phases with the size from 5 μm to 30 μm and the strip-like morphology in the alloys with Al-Zr master alloy addition.The size of coarse phases is increased with the increase of Zr in the master alloys.Absence of coarse phases in the alloys with the Zr addition in form of pure particles can be observed.The fracture analysis shows that the coarse phases are the initiation resource of cracks

leading to the deterioration of the mechanical properties severely.The tensile strength and elongation are 820 MPa and 5%

respectively

of the alloy with the Zr addition in form of pure particle while their are 710MPa and 3.5%

respectively

of one with Zr addition in form of Al-Zr master alloys.