Effects of electromagnetic frequency on the microstructure and mechanical properties of Al70Zn10Mg10Cu5Si5 medium entropy alloy

Abstract

In this work, an Al70Zn10Mg10Cu5Si5 medium entropy alloy was for the first time prepared by electromagnetic stirring casting. Electromagnetic casting has little effect on the generated phases in the as-cast alloys, and these phases are mainly composed of the α-Al solid solution, Mg2Si phase, Al2Cu phase, and MgZn2 phase. However, the electromagnetic frequency significantly affects the second phase's content, distribution, and morphology, especially for the Mg2Si phase, whose average particle size decreases from 40.0 to 17.7 μm. In addition, the compression mechanical properties were tested at room temperature, and it was found that the hardness, strength, and plasticity were effectively improved by applying a specific electromagnetic frequency. The optimal electromagnetic frequency was 20Hz in this work, under which the corresponding Vickers hardness, ultimate compressive strength δbc, and compressive yield strength δsc were 177 HV, 554 MPa, and 500 MPa, respectively. Moreover, mechanisms on the enhanced mechanical properties for the alloy fabricated with a proper electromagnetic frequency were systematically discussed. This first exploratory study can provide a reference for preparing Al-based medium entropy alloys by electromagnetic stirring casting.