Effects of Mg–Zn–Y quasicrystal addition on the microstructures, mechanical performances and corrosion behaviors of as-cast AM60 magnesium alloy

Abstract

In this work, the as-cast Mg–50Zn–5Y (mass fraction) master alloy containing Mg42Zn50Y8 (mole fraction) icosahedral quasicrystal phase (I-phase) was prepared. The influences of addition amount of the Mg–50Zn–5Y master alloy on the microstructure, mechanical performances and corrosion properties of AM60 alloys were studied, aiming to investigate the structure-activity relationship for optimizing the microstructures and properties of AM60 alloys. The results indicated that the continuous reticulation structure could be broken and the precipitated phases could be significantly refined by adding the Mg–50Zn–5Y quasicrystal master alloy. The quasicrystal-reinforced AM60 alloys exhibited better mechanical properties and corrosion resistance than unmodified one. The modified AM60 alloy with 6 wt% of the Mg–50Zn–5Y quasicrystal master alloy had the optimal mechanical performances and corrosion resistance such as a Brinell hardness of 74 HB (increased by 37.0%), an ultimate tensile strength of 205 MPa (increased by 24.3%), a yield strength of 99 MPa (increased by 32.0%) as well as a corrosion rate of 1.35 × 10−2 mm·year−1 (decreased by 93.1%). The broken of the continuous reticulation structure and the refinement of the precipitated phases were responsible for the improvement of mechanical performances and corrosion resistance.