Evolution of strength with rare-earth content in highly-alloyed Mg-Gd-Y alloys

Abstract

Mechanical properties of extruded Mg-Gd-Y alloys are investigated as a function of rare-earth content within the high concentration range. The strength is found to change non-monotonously with the total rare-earth content. A maximum of tensile yield strength (275 MPa) and ultimate tensile strength (348 MPa) is achieved at ∼18 wt. % rare-earth content. While grain refinement and solid solution strengthening mechanism are found to primarily contribute to the value of yield strength, the change of solid solution strengthening due to the competitive balance of solid solubility between the alloying species is demonstrated to dominate the non-monotonous evolution of tensile yield strength upon rare-earth content. In addition, the increased block precipitates deteriorate the capacity of plastic deformation and decrease tensile strength at high rare-earth content. The present findings provide helpful guidance for the intelligent design of highly-alloyed Mg alloys.