INFLUENCE OF Y ON THE MICROSTRUCTURE, MECHANICAL PROPERTIES AND FRACTURE MECHANISM OF Mg-8Ll-3Zn ALLOY

摘要

The influences of Y on the microstructure, mechanical properties and fracture mechanism of as-cast Mg-8Li-3Zn alloy were investigated. The experimental results show that the ultimate tensile strength of the dual-phase Mg-8Li-3Zn alloy is up to 150.4MPa while the elongation is up to 31.5%.After adding yttrium to the alloys, the ultimate tensile strength of Mg-8Li-3Zn-1.5Y increases to 176.5 MPa, but the elongation reduces to 16.5%. The failure mode of Mg-8Li-3Zn alloy is typical ductile rupture whereas some cleavage patterns appear on the fracture surface with the addition of Y. The microcrack originates from the interior of a-Mg phase, passes through the a-Mg phase with cleavage fracture mode and crazes the p-Li phases with dimple fracture.