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Continuous powder extrusion, a new powder consolidation technology, is used to process alloy powders that are difficult to form. In the paper, Al-28.5Si alloys were successfully prepared by continuous powder extrusion, and the influences of particle size on the microstructure and tensile property have been investigated. In the as-extruded rods, the primary Si phase is dispersed in the α-Al matrix. As the powder size reduces from more than 75 μm to less than 25 μm, the equivalent diameter of the primary Si particles consecutively decreases, but the shape factor increases. Comparing the Si particles in the alloy rod and the powder, it is found that the eutectic Si phase disappears during continuous extrusion. Primary Si particles change from coarse and irregular to round. Specifically, the ultimate tensile strength and elongation at break of the powder-extruded alloy further increase from 211 MPa to 266 MPa and 0.99% to 2.21%. Moreover, the fracture mechanism of alloy rods is the brittle fracture.

The commercial Al-5.72Zn-2.36Mg-1.66Cu (7075) alloys were prepared by the spray Conform (SC) technique consisting of the spray forming and Conform extrusion. The extrusion ratio (ER) was selected as the variable parameter to study the influence mechanism on the microstructures and properties while keeping the other parameters unchanged. The microstructures and properties were investigated by scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM), x-ray diffraction (XRD), electron backscatter diffraction (EBSD) and tensile tests. Concretely, the changing rules of the grains, second phases, tensile strength and elongation with ER were researched respectively. Results indicate that a fine equiaxed grain microstructure with low level of segregation and porosity was achieved by SC. And the intergranular and intragranular phases were fine and homogeneous before and after retrogression and re-aging (RRA). The dispersion and tensile strength are positive to ER, but the grain size (GS) is inverse. Meanwhile, the elongation increases firstly and then decreases with increasing ER.