Correlative Raman Spectroscopy-SEM Investigations of Sintered Magnesium-Calcium Alloys for Biomedical Applications

Area of Science:

• Biomaterials Science
• Materials Science
• Metallurgy

Background:

• Metal injection molding (MIM) and powder metallurgy (PM) are key for producing magnesium (Mg) alloys for biomedical applications.
• Understanding material microstructure, including homogeneity and secondary phases, is vital for predicting degradation and biocompatibility.
• Identifying carbon-related impurities in Mg-0.6Ca specimens is challenging but critical for their performance.

Purpose of the Study:

• To develop and apply a correlative approach using Raman spectroscopy and scanning electron microscopy (SEM) for identifying carbon residuals in Mg-0.6Ca.
• To investigate the origin and nature of carbonaceous phases formed during the MIM and PM processing of Mg-0.6Ca.
• To enhance the understanding of microstructure-homogeneity and its impact on degradation and biocompatibility of Mg biomaterials.

Main Methods:

• Correlative analysis combining Raman spectroscopy and scanning electron microscopy (SEM).
• Micro-Raman measurements to detect characteristic carbon modes (~1370 cm⁻¹, ~1560 cm⁻¹, ~1865 cm⁻¹).
• Analysis of binder-derived carbon residuals and their reactions at elevated temperatures during debinding and sintering.

Main Results:

• Raman spectroscopy identified elemental carbon and C≡C stretching modes, indicating carbonaceous residuals.
• Carbon residuals were traced to polymeric binder components used in MIM fabrication.
• The presence of free carbon and calcium carbide phases was inferred, alongside Mg₂Ca, oxide, and silicate phases.

Conclusions:

• The correlative Raman spectroscopy and SEM approach is effective for characterizing residual carbon phases in PM-processed Mg biomaterials.
• Residual carbon originates from binder decomposition and reaction during thermal processing.
• This characterization is essential for developing advanced Mg alloys with predictable degradation and biocompatibility for biomedical use.