Biodegradable WE43 Magnesium Alloy Produced by Selective Laser Melting: Mechanical Properties, Corrosion Behavior, and In-Vitro Cytotoxicity

Abstract

In this work, selective laser melting (SLM) technology was used to prepare Mg-4Y-3Nd-Zr (WE43) alloy. This alloy and production method are promising for the design of biodegradable implants. The aim of this study was to investigate the chemical composition, microstructure, mechanical properties, corrosion behavior in simulated body fluid (SBF), and cytotoxicity of the alloy produced by SLM method and to compare it with conventionally gravity cast reference alloy. Analysis of the surface of the revealed an oxygen content of 7 wt.%. Undesirable unmelted and only partially adhered spherical particles of the starting powder were also found. The microstructure of the material was very fine and consisted of α-Mg dendritic matrix, β-Mg41(Nd, Y)5 intermetallic phase, Y2O3 inclusions, and 0.6 vol.% of residual porosity. The Vickers hardness, compressive yield strength, compressive strength, and maximum compressive strain were 88 HV0.1, 201 MPa, 394 MPa, and 14%, respectively, which are close to the reference values in as-cast. The in vitro corrosion rates determined by immersion and potentiodynamic tests were 2.6 mm/year and 1.3 mm/year, respectively. Cytotoxicity tests indicated good biocompatibility of the 3D-printed alloy.

Additive manufacturing of magnesium and its alloys: process-formability-microstructure-performance relationship and underlying mechanism

“…They indicate that the grain boundaries, as crystallographic defects, are more susceptible to be corroded than the grains and thus facilitate corrosion process of Mg alloys. Li et al found that the WAAM-processed AZ31 alloy with finer grains exhibited an inferior corrosion resistance in comparison with the as-cast one with coarser grains [81], although no defects were detected in both samples, which was different from the interpretation by Lovašiová et al [129]. Li et al believed that the variation of corrosion mechanism with grain size is the main reason causing this phenomenon [81].…”

“…Wu et al illustrated that the LPBF-processed ZK60 owned a better corrosion resistance than the as-cast ZK60 as indicated by a lower I corr of 8.89 µA•cm −2 as compared with 18.5 µA•cm −2 for as-cast ZK60 with a nobler E corr of −1.52 V vs. SCE, and also a 30% decrease in hydrogen evolution rate [47]. However, Lovašiová et al demonstrated that the LPBF-processed WE43 alloy had a higher corrosion rate in SBF than the as-cast WE43 alloy [129]. Similar to the findings by Lovašiová et al, an inferior corrosion resistance of WAAM-processed Mg alloy to as-cast counterpart was also reported by Li et al [81].…”

The Characterization of a Biodegradable Mg Alloy after Powder Bed Fusion with Laser Beam/Metal Processing for Custom Shaped Implants

“…Apart from well-known fields of use, such as the automotive field, aerospace and electronics, magnesium alloys are currently widely tested as biomedical components, not only for their high strength-to-weight ratio [1,2], but also for their good structural and mechanical biocompatibility [3,4]. Moreover, in a series of biocompatible materials, magnesium alloys fall under the category of biodegradable materials [5,6], a very useful physical process that prevents a second surgery for removing an anterior inserted bone implant after bone healing due to the fact that magnesium can easily disintegrate in time in human physiological environments [7].…”

“…The main advantages of using magnesium alloy for bone implants refers to the fact that it exhibits mechanical performances similar to human bone (a low density of 1.74 g/cm 3 and a low elastic modulus of about 40-44 GPa, very close to that of cortical bone at 30 GPa, [14]) and, during degradation in human environments, it represents an essential nutrient which promotes bone growth and mineralization [8]. The main disadvantage is the risk of more the rapid degradation of magnesium alloy prior to the bone healing process, a fact that requires a difficult co-ordination between the two processes: degradation versus healing [15,16].…”

Combination of Scanning Strategies and Optimization Experiments for Laser Beam Powder Bed Fusion of Ti-6Al-4V Titanium Alloys

“…Laser beam powder bed fusion (L-PBF) is one of the most widely used and researched metal additive manufacturing (AM) technologies and belongs to the powder bed melting technology, which is based on the principle of using a high-energy laser beam to melt a metal powder bed layer by layer to create solid parts [1][2][3][4][5][6][7][8][9]. L-PBF technology is widely used in automobile manufacturing [10], aerospace [11,12], and medical industries [13,14].…”