3D X-ray Tomography Analysis of Mg-Si-Zn Alloys for Biomedical Applications: Elucidating the Morphology of the MgZn Phase

Author(s)

de Gouveia, Guilherme Lisboa ; Ganju, Eshan ; Moura, Danusa ; Morankar, Swapnil K. ; Spinelli, Jose Eduardo ; Chawla, Nikhilesh

• Document type: Journal article
• Source: APPLIED SCIENCES-BASEL; v. 14, n. 17, p. 20-pg., 2024-09-01.

Abstract

Temporary metal implants, made from materials like titanium (Ti) or stainless steel, can cause metabolic issues, raise toxicity levels within the body, and negatively impact the patient's long-term health. This necessitates a subsequent operation to extract these implants once the healing process is complete or when they are outgrown by the patient. In contrast, medical devices fabricated from absorbable alloys have the advantage of being biodegradable, allowing them to be naturally absorbed by the body once they have fulfilled their role in facilitating tissue healing. Among the various absorbable alloy systems studied, magnesium (Mg) alloys stand out due to their biocompatibility, mechanical properties, and corrosion behavior. The existing literature on absorbable Mg alloys highlights the effectiveness of silicon (Si) and zinc (Zn) additions in improving mechanical properties and controlling corrosion susceptibility; however, there is a lack of comprehensive quantitative morphological analysis of the intermetallic phases within these alloy systems. The quantification of the complex morphology of intermetallic particles is a challenging task and has significant implications for the micromechanical properties of the alloys. This study, therefore, aims to introduce a robust set of morphometric parameters for evaluating the morphology of intermetallic phases within two as-cast Mg alloys with Si and Zn additions. X-ray Computed Tomography (XCT) was used to capture the 3D tomographic data of the alloys, and a novel pair of morphological parameters (ratio of convex hull to particle volume and convex hull sphericity) was applied to the 3D tomographic data to assess the MgZn phase formed in the two alloys. In addition to the impact of composition, the effect of solidification rate on the morphological parameters was also studied. Furthermore, Scanning Electron Microscopy (SEM) and Energy-Dispersive Spectroscopy (EDS) were employed to gather detailed 2D microstructural and compositional information on the intermetallics. The comprehensive characterization reveals that the morphological complexity and size distribution of the MgZn phase are influenced by both compositional changes and the solidification rate. However, the change in MgZn intermetallic particle morphology with size was found to follow a predictable trend, which was relatively agnostic of the chosen casting conditions. (AU)

• FAPESP's process: 19/01432-8 - Microstructure development, corrosion and mechanical resistances of Mg-Si and Mg-Si-(x) alloys for biomedical application
• Grantee: Guilherme Lisboa de Gouveia
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 23/06107-3 - Study of the growth of AlFe primary phases in Al alloys and of intermetallic layers in Sn-Bi-X/copper joints
• Grantee: José Eduardo Spinelli
• Support Opportunities: Regular Research Grants
• FAPESP's process: 22/01895-0 - Evaluation of the microstructural evolution of biomedical absorbable Mg alloys during corrosion process through non-destructive 3D analysis using the Absorption Contrast X-ray Tomography (ACT) technique
• Grantee: Guilherme Lisboa de Gouveia
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate