Preparation and characterization of laser-melted Mg–Sn–Zn alloys for biomedical application

Abstract

The rapid degradation rate of Magnesium (Mg) alloy limits its biomedical application even though it possesses outstanding biological performance and biomechanical compatibility. In this study, a combined method of laser rapid melting and alloying Zinc (Zn) was proposed to decrease the degradation rate of Mg-Sn alloy. The microstructure, degradation behaviors and mechanical properties of the laser-melted Mg-5Sn-xZn (x = 0, 2, 4, 6 and 8 wt.%) alloys were investigated. The results indicated that the grain size of the alloys decreased with increasing Zn content, due to the increased number of nucleation particles formed in the process of solidification. Moreover, the laser-melted Mg-Sn alloys possessed finer grains compared with traditional as-cast and as-rolled Mg-Sn alloys. The degradation rate of the alloys decreased with increasing Zn content (0-4 wt.%), which was ascribed to the grain refinement and the formation of Zn(OH) protective layer. However, the degradation rate increased as the Zn content further increased (4-8 wt.%), which was caused by the galvanic corrosion between the Mg matrix and the generated MgZn phase. Besides, Zn also increased the hardness of the alloys owing to the grain refinement strengthening and solid solution strengthening.

The microstructure, degradation behavior and cytotoxicity effect of Mg–Sn–Zn alloys in vitro tests

“…4) show that the secondary phases are not continuous webs in the grain boundaries but instead occur in discontinuous form. Therefore, the corrosion resistance properties obtained in the present study are better than those reported in the literature [14,15,17,34]. In another similar study regarding the effect of secondary phases on corrosion resistance [14], corrosion rates were applied to Mg-Sn alloys containing different amounts of Sn.…”

“…In a similar study, there was evidence that the formation of a finer grain in the microstructure increases the corrosion resistance [15]. According to another study [40], microstructural parameters, such as phase distribution and grain size, affect the degradation behaviour of Mg-based alloys.…”

“…The alloys were applied to 100, 320, 400, 600, 800, 1000, 1200, and 1500 grit grinding stages for preparation for metallographic examination. Processes of cleaning with absolute ethyl alcohol, drying in desiccator and polishing with 1-µm diamond suspension were carried out according to the literature [15,22] The alloys were etched with using a mixture of 95% ethyl alcohol and 5% nitric acid (HNO 3 ), which is well used in Mg-based alloys [23][24][25]. After etching, the alloys were cleaned with distiled water and absolute ethyl alcohol.…”

“…The reason for choosing 5% Sn in determining Mg5Sn-xZn alloy composition in the present study is that the addition of a greater ratio results in an increased amount of H 2 gas being released by the galvanic corrosion of the alloy, lowering the corrosion resistance and facilitating faster processing of the corrosion mechanism. In similar studies on the corrosion of Mg-Sn alloys, the chosen Sn ratio has not been above 5% by weight [14,15]. Furthermore, in cell culture studies, Mg-Sn alloys produced by the addition of Sn above this ratio have been found to damage MG63 cells (bone) [16].…”

The Effect of Processing Pass on the Microstructure and Mechanical Properties of a Friction Stir Processed As-Cast Mg-6 wt % Sn Alloy

“…Therefore, Mg-Sn alloys have been recognized as potential heat-resistant Mg alloys with an engineering application value in recent years [4][5][6]. Meanwhile, since the Sn element is an essential trace element in the human body and noncytotoxic, Mg-Sn alloys are promising bio-Mg alloys used as a bio-implant material [7,8]. Therefore, the study of Mg-Sn alloys is of essential research value.…”