Microstructure and mechanical properties of Al–Si–Ni–Ce alloys prepared by gas-atomization spark plasma sintering and hot-extrusion

► There are distinct microstructures in the as-atomized powders with different size. ► The morphology of Al 11Ce 3 crystals is related to the Ni content. ► Tiny Al 3Ni precipitated from the supersaturated matrix after SPS process. ► Hot-extrusion leads to the improved microstructures. ► This kind of alloy exhibits high comprehensive mechanical properties. Al–Si–Ni–Ce alloys with the composition of Al 78.5Si 19Ni 2Ce 0.5, Al 76Si 19Ni 4Ce 1 and Al 73Si 19Ni 7Ce 1 were atomized and then sintered by using spark plasma method. The microstructure of the as-atomized powders, sintered and hot-extruded samples was analyzed. The influences of granularity and sintering parameters including time and temperature on the density of sintered alloy were also discussed. It is shown that the atomized powders are composed of Si, Al 11Ce 3, Al 3Ni and alpha Al. Tiny Al 3Ni particles precipitate from supersaturated matrix near the powder boundaries during SPS. Hot-extrusion process leads to the layer structure and more homogeneous distribution of precipitates. These alloys exhibit high comprehensive mechanical properties with combination of high Vicker's micro-hardness, moderate tensile properties and elongation, which provide a novel kind of promising engineering materials.