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

Abstract

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.