Rare Earth Modification Of Casting Al-Si-Mg Alloy And The Study Of The Aging Characteristics

The addition of rare earth can significantly change the morphology and mechanical properties of casting Al-Si-Mg alloy, it has a broad application prospect in the defense, transportation, building materials, wire and cable.Rare earth elements generally introduced into the alloy by elemental, intermediate alloy and oxide form. The introduction will have effect on aluminum alloy, but few related research has been reported. Al-Si-Mg Cast alloy generally improve the mechanical properties by the way of aging treatment, related research has been more fully reported, but the research about aging characteristics of the rare earth modified Al-Si-Mg alloy cast is less. This paper studied the change about microstructure and mechanical properties modified by different introduction, and the aging characteristics of rare earth modified Al-Si-Mg cast alloy.There are obvious different effect modified by different introduction way. Introduce oxide, the rare earth have a few refinement effect for the ZL101 alloy, But deterioration is not obvious, small rare earth can certain extent strengthen the matrix alloy. When the content of rare earth oxides is greater than 0.6%, the strength of the alloy is straight down; Al-La Alloy Can refine and deterioration the ZL101 alloy, and the hardness of the alloy has also been significantly improved.XRD result suggest that the addition of La2O3 has not changed phase in ZL101 alloy. Al-La intermediate alloy produce Al8Si8MgLa2,The new compound accumulation in the interface between the eutectic silicon and aluminum liquids, it decrease the mechanical properties of the alloy. The morphology of eutectic silicon have changed after solide solution and aging treatment, the strip morphology of the eutectic silicon almost become spherical and granular after solide solution and aging treatment.By the way of introducing the La、Ce intermediate alloy has distinct refining effect. The most distinct refinement occurs when amount of rare earth is 0.6% and the hardness increased most significantly at the same time. It reduce the hardness of cast alloy and aging alloy while adding too much, Especially 1.6%,On the study of precipitated sequence, the exothermic peak appears in advance compared to the original alloy. But the enthalpy is higher than Z1104 ally.The introducing ways of Al-Ce、Al-La alloy have obvious effect on the strength of Al-Si-Mg alloy. The strengthening effect is best when the introduction of Al-La alloy is 0.5%, The strengthening effect is best when the introduction of Al-Ce alloy is 0.6%.rare earth elements La, Ce delay the peak aging time on the casting of Al-Si-Mg alloy, with the introduction of rare earth elements increased, the peak aging time delay effect is more obvious.The introduction of rare earth alloy did not change the precipitation sequence. Al-Re alloy delay the release strengthening phase(β"、β’)and stable phase(Mg2Si) of alloy. The more adding of Al-Re alloy, the more obvious of inhibitory effect.The temperature has a significant impact on hardening behavior of alloy. With the increasing of aging temperature, peaking aging time is short.