Effect of Sm content on microstructure and properties of extruded Mg-6Al-2Sr alloy

Abstract

In this paper, the strengthening mechanism of different Sm content on extruded Mg-6Al-2Sr alloy was studied. The microstructure was observed by metallographic experiment, X-ray diffraction, scanning electron microscopy and transmission electron microscopy, and the effect of Sm content on the microstructure of the alloy was analyzed by EBSD. The main experiment in this paper is the extrusion experiment of Mg-6Al-2Sr cast alloy with different Sm content. The results show that with the increase of Sm content, the generated Al₂Sm phase is broken under the action of extrusion, and uniformly dispersed at the grain boundary along the extrusion direction, which hinders the grain growth. However, with the increase of Sm content, the Al₂Sm phase increases and aggregates at the grain boundary, which has an adverse effect on the mechanical properties of the alloy. When the Sm content is 1.5 wt%, the average grain size of the alloy is the finest, and its tensile strength, yield strength and elongation reach 297.9 MPa, 257.8 MPa and 21.3%, respectively. The hardness reaches HV78.9, which is 15.6% higher than that of the alloy with 0 wt% Sm content. The yield strength increased by 34.6% and the elongation increased by 34.8%.

Keywords

Mg-6Al-2Sr-xSm alloy / microstructure / electron backscattered diffraction (EBSD) / mechanical properties

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Foundation item: Project(51975167) supported by the National Natural Science Foundation, China; Project(2022ZX01A01) supported by the Key R&D Program in Heilongjiang Province, China