Utilization of Microalloying with Rare Earth Elements and Hot Extrusion for Remarkable Grain Refinement and Enhancement of Mechanical Properties of as-Cast Magnesium Alloy

Subject Areas : Casting

Hooman Abedi ¹ , Massoud Emamy ^{2 *} , Hamed Mirzadeh ³ , Jafar Rassizadehghani ⁴ , M. Ra'ayatpour ⁵

1 - School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, P.O. Box 11155-4563, Tehran, Iran
2 - School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, P.O. Box 11155-4563, Tehran, Iran
3 - School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, P.O. Box 11155-4563, Tehran, Iran
4 - School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, P.O. Box 11155-4563, Tehran, Iran
5 - School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, P.O. Box 11155-4563, Tehran, Iran

Received: 2020-05-14 Accepted : 2020-06-03 Published : 2020-11-01

Keywords: Mechanical Properties, Recrystallization, Mg alloys, Ultrafine grained microstructure,

Abstract :

The effects of micro-addition by rare earth (RE) elements (via cerium-based mischmetal) and hot deformation (via extrusion process) on the microstructure and mechanical properties of Mg-0.5Zn-0.5Zr alloy were studied. Optical microscopy, scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and tensile testing were used for characterization of alloys in the as-cast and wrought conditions. It was found that the addition of 0.5 wt% RE combined with the hot extrusion process could remarkably refine the grain size from 1320 µm for the as-cast Mg-0.5Zn-0.5Zr alloy to the recrystallized grain size of 1.3 µm for the extruded Mg-0.5Zn-0.5Zr-0.5RE alloy. Compared to the as-cast counterparts, the ultimate tensile strength (UTS) and total elongation to failure were significantly enhanced by the extrusion process. Quantitatively, the UTS of ~ 300 MPa with the total elongation of ~ 18% was obtained for the extruded Mg-0.5Zn-0.5Zr-0.5RE alloy, which reveals the favorable effects of the ultra grain refinement on the enhancement of the mechanical properties of magnesium alloys.