Effect of Zr on the cast microstructure and mechanical properties of Al-4.0Cu-1.4Mg-0.5Mn alloy by electromagnetic continuous casting

The effects of Zr on the cast microstructure and mechanical properties of Al-4.0Cu-1.4Mg-0.5Mn high strength aluminum alloy by electromagnetic continuous casting were studied by using optical microscope, hardness measurement, tensile test, scanning electron microscope and XRD etc. The results show that Zr can remarkably improve the properties of the Al-4.0Cu-1.4Mg-0.5Mn alloys. The strengthening mechanism is considered as fine grain strengthening and dispersion strengthening; The macrohardness of the alloy with Zr increases by 3.91%, the tensile strength and the yield strength of alloy with Zr can raise about 3.90% and 4.82% respectively and elongation improves by 48.66% compared with that of the alloy without Zr in as-cast state. The alloy with Zr expresses ductile fracture mechanism, but the dimples are nonuniform distribution, there are some second-phases in the edge and center of dimple.