Characteristics on microstructure and mechanical performances of 6111Al influenced by Ce-containing precipitates

In this work, the effects of Ce addition (0, 0.1 wt%, 0.3 wt%, 0.5 wt% and 0.7 wt%) on the evolution of microstructure and mechanical properties of 6111Al alloy and strengthening mechanism of 6111Al–Ce alloy were systematically investigated by a polarizing microscope, a scanning electronic microscope, an energy dispersive spectroscope and a high-resolution transmission electron microscope. The results indicate that with 0.3 wt% Ce addition, the α-Al grains show the equiaxed crystal morphology with the average size decreasing from 137 to 57 μm and numerous small AlCeSi phases with lump-like or plate-like morphology are distributed closely along the grain boundary. The peak yield strength, ultimate tensile strength and elongation of 6111Al–Ce alloy reach to 279 MPa, 316 MPa and 12.1%, respectively, which is attributed to the grain refinement strengthening and the formation of nanosized Al₁₁Ce₃ precipitates. Eventually, this investigation gives us instructive suggestion to prepare the new kind of aluminum alloy with high strength and high ductility.