Effect of Mischmetal on Microstructure and Mechanical Properties of Superlight Mg-Li Alloys

Abstract

The influence of mischmetal (lanthanum and cerium) on the microstructure and mechanical properties of Mg-9Li-3Al-xRE (x=0, 0.5, 1, 1.5, 2, wt%) alloys was investigated by optical microscope, scanning electron microscope (SEM) with an energy dispersive spectroscope (EDS), and X-ray diffraction (XRD). In as-cast alloys, Al4RE phase is formed, the content of Mg17Al12 phase and the volume fraction of α-Mg phase decrease. In addition, α-Mg phase is refined and the mechanical properties of Mg-9Li-3Al-xRE alloys are improved. However, with increasing mischmetal content, the size of Al4RE phase increases and the mechanical properties decrease. In extruded alloys, Al4RE phase is broken into the particles of 1~3 μm in the β-Li matrix phase and α/β interphase. And the best mechanical properties are obtained for Mg-9Li-3Al-1.5RE alloy with a tensile strength of 228.3MPa and elongation of 20.8%, increased by 88.6% and 197.4%, respectively, compared with as-cast Mg-9Li-3Al alloy.

Influence of Neodymium on Microstructure and Mechanical Properties of Mg-9Li-3Al Alloy

“…6 represents the SEM picture of fractural morphologies of Mg-9Li-3Al and with 1.5wt.%Nd alloys. In Mg alloys, predominantly the nature of fractures are brittle in the mode of cleavage or quasi-cleavage fracture by reason of HCP structure and [13]. From Fig.…”

Effect of KOBO Extrusion and Following Cyclic Forging on Grain Refinement of Mg–9Li–2Al–0.5Sc Alloy

“…A dual-phase Mg-Li-Zn alloy has been processed by a severe plastic deformation (SPD) method which is a combination of extrusion and rolling processes and enables the production of a very fine grain structure and reveals a high superplastic deformation [7,12]. The effect of various quaternary additions like zinc [8,9], yttrium [13,14], mischmetal [15], strontium [16], neodymium [17], silicon [18], indium [19], tin [20] and scandium [21][22][23] to the ternary Mg-Li-Al alloys were also studied. In most cases, except for the Si addition, their positive effect on mechanical properties was reported and the mechanisms of improvement of properties were related to grain refinement and second phase strengthening.…”