Effect of vibration on interfacial microstructure and mechanical properties of Mg/Al bimetal prepared by a novel compound casting

Abstract

In this work, a vibration was applied in the preparation of the Mg/Al bimetal by a novel compound casting in order to improve the mechanical properties of the Mg/Al bimetal, and the effect of the vibration on the interfacial microstructure and mechanical properties of the Mg/Al bimetal was investigated. The results indicated that the vibration had a significant effect on the interfacial microstructure and mechanical properties of the Mg/Al bimetal, but it did not change the phase compositions of the interface, which was composed of layer I (Al 3 Mg 2 +Mg 2 Si), layer II (Al 12 Mg 17 +Mg 2 Si) and layer III (Al 12 Mg 17 /δ-Mg). Without vibration, the Mg 2 Si phase with a needle-like morphology mainly aggregated in the layer II of the interface. After the application of the vibration, the SEM and EBSD analysis results showed that the Mg 2 Si and Al 3 Mg 2 phases in the interface were obviously refined, and the distribution of the Mg 2 Si became more uniform, due to the strong forced convection of the molten metal resulting from the vibration. The TEM analysis indicated that the interface between the Al 3 Mg 2 and Mg 2 Si phases was non-coherent, suggesting the Mg 2 Si particles cannot act as a heterogeneous nucleation base during the solidification process of the interface. Compared to the Mg/Al bimetal without vibration, the shear strength of the Mg/Al bimetal with vibration increased by about 50% from 31.7 MPa on average to 47.5 MPa, and the hardness of the layer I of the interface increased, and the hardness of the layer III decreased. The fracture surface transformed from a flat fracture morphology without vibration to an irregular zigzag fracture morphology.