Natural ageing responses of duplex structured Mg-6%Li and Mg-6%Li-6%Zn-1.2%Y alloys have been investigated. Microstructural analyses revealed that the precipitation and coarsening process of α-Mg particles could occur in β-Li phases of both two alloys during ageing process. Since a certain amount of Mg atoms in β-Li phases were consumed for the precipitation of abundant tiny MgLiZn particles, the size of α-Mg precipitates in Mg-6%Li-6%Zn-1.2%Y alloy was relatively smaller than that in Mg-6%Li alloy. Micro hardness measurements demonstrated that with the ageing time increasing, the α-Mg phases in Mg-6%Li alloy could have a constant hardness value of 41 HV, but the contained β-Li phases exhibited a slight age-softening response. Compared with the Mg-6%Li alloy, the age-softening response of β-Li phases in Mg-6%Li-6%Zn-1.2%Y alloy was much more profound. Meanwhile, a normal age-hardening response of α-Mg phases was maintained. Tensile results indicated that obvious ageing-softening phenomenon in terms of macro tensile strength occurred in both two alloys. Failure analysis demonstrated that for the Mg-6%Li alloy, cracks were preferentially initiated at α-Mg/β-Li interfaces. For the Mg-6%Li-6%Zn-1.2%Y alloy, cracks occurred at both α-Mg/β-Li interfaces and slip bands in α-Mg and β-Li phases.
Abstract. In the present paper, the Mg-Zn-Y-Nd alloy was prepared by casting, heat treatment and hot extrusion. The microstructure and mechanical properties of the alloys were tested by OM, SEM, TEM and tensile test. The results showed that the Mg 3 Zn 2 Y 3 phase is the main strengthening phase and forms the eutectic structure with α-Mg matrix in the as cast alloy. The strengthening phases semi-continuously connect and separate the α-Mg matrix into cell structure. The average grain size of the as cast alloy is about 60 μm. The heat treatment promotes the solid solution of the strengthening phase and precipitation of small particles inside grain.Compared with the as cast alloy, the heat treatment increases grain size a little and mechanical properties more than 30%. The hot extrusion refines the grain and strengthening phase, which increase the mechanical properties significantly. Moreover, the great deformation by the hot extrusion results in the ultrafine structure and abundant of crystal defects. The intersection of micro-twins lead to the special region with nanometer size. IntroductionMagnesium (Mg) alloys have attracted great attention as the light weight structural materials owing to their high specific strength, low density, ease of recycling and good damping, which can be applied in many fields, including implants, hand tools, sports equipment, automobiles, aerospace applications and electronic equipment [1][2][3][4]. Moreover, the recent research exhibited that the clinic trial of coronary stent made by rare earth doped Mg alloy exhibited good therapeutic effect without thrombosis, which demonstrated the good application prospect of Mg based implant [5]. However, the hexagonal closepacked (HCP) crystal structure of Mg limited the number of initiation slip systems during deformation at relative low temperature, which resulted in the poor deformability of Mg alloy [6]. The poor ductility and low strength of Mg alloy handicapped its wide application. To conquer these shortcomings of Mg alloy, many methods had been applied [7][8][9]. Alloying and thermal processing had been thought as the efficient method to improve the mechanical properties of Mg alloy at room and high temperature.Recently, the investigations [10-12] on biomedical magnesium alloys revealed that the addition of Zn could improve its mechanical properties and corrosion resistance with little influence on its biocompatibility, because the Zn is the essential element of the human body. Then a series of new magnesium alloys for biomedical application were developed [13][14][15]. The research of Zhang et al. [10] exhibited that Zn addition in Mg could increases the mechanical performance and biocompatibility, and the Mg-6Zn (wt.%) alloy was the best choice. But the mechanical properties of Mg-Zn alloy is not
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.