Influence of Al2Y particles on mechanical properties of Mg-11Y-1Al alloy with different grain sizes

Abstract

Manipulating the grain size and the distribution of precipitates has been widely used for tailoring mechanical properties of magnesium alloys. In this work, we systematically studied the influence of LPSO lamellas, Al2Y particles as well as grain size on the mechanical properties of the Mg-11Y-1Al alloys. The LPSO phase has little effect on the strength and ductility of the Mg-11Y-1Al alloys. Grain refinement gives rise to the simultaneous improvement of the strength and ductility. The yield strength is improved from 160 MPa to above 300 MPa and the elongation is increased from 4% to more than 13% with the grain refinement from 40 μm to 5 μm. Based on the CPFEM simulation results, it is found that stress concentration generally increases at the adjacent of the Al2Y particle at the scenario of the 40 μm grain size. Cracks thus nucleate at the adjacent area of the Al2Y particles, which results in poor ductility. With the reduction of grain size to 5 μm, the ductility is enhanced with alleviating the stress concentration around micrometer-size Al2Y particles and subsequent activating <c+a> dislocations. Such a finding provides a guideline in tailoring mechanical properties of other Mg-RE-Al alloys for demanding applications.