Microstructure Regulation and Mechanical Properties of Mg–6xZn–xY Alloys Containing Icosahedral Quasicrystalline Phases

Abstract

Mg–6xZn–xY (x = 0.8, 5, and 7 wt%) alloys containing an icosahedral quasicrystal phase (I‐phase) are synthesized, and the effects of Y doping on the microstructure and mechanical properties of the Mg matrix and I‐phase are investigated. The results show that as the Y content increases, the I‐phase content gradually increases, with the distribution of the I‐phase changing from a discontinuous to a continuous network and lamellar structures. Additionally, the eutectic structure (α‐Mg + I‐phase) in the alloys gradually increases, while the Mg matrix area decreases. The tensile strength of the as‐cast alloy initially increases and then decreases, reaching a maximum value at Y = 5. Heat treatment of the Mg–30Zn–5Y alloy reveals an optimal solid solution temperature of 320 °C, resulting in a tensile strength of 175.09 MPa and quasicleavage fracture characteristics. The maximum tensile strength of the alloy is achieved when the I‐phase distribution is continuous and the porosity of the Mg matrix is ≈66%. These results provide guidance for the microstructural design of I‐phase‐reinforced Mg alloys with rare earth elements to enhance their mechanical properties.