Biodegradable magnesium alloys have emerged as promising alternatives to permanent metallic implants due to their unique combination of mechanical compatibility with bone and complete resorption, addressing the persistent issues of stress shielding and secondary removal surgeries. This review critically examines the historical development of magnesium-based biomaterials, highlighting advances in alloy design, manufacturing processes, and surface engineering that now enable tailored degradation and improved clinical performance. Drawing on recent clinical and preclinical studies, we summarize improvements in corrosion resistance, mechanical properties, and biocompatibility that have supported the clinical translation of magnesium alloys across a variety of orthopedic and emerging medical applications. However, challenges remain, including unpredictable in vivo degradation kinetics, limited long-term safety data, lack of standardized testing protocols, and ongoing regulatory uncertainties. We conclude that while magnesium-based biomaterials have advanced from experimental concepts to clinically validated solutions, further progress in personalized degradation control, real-time monitoring, and harmonized regulatory frameworks is needed to fully realize their transformative clinical potential.

Design and examination of the new biosoluble casting alloy of the system Mg–Zr–Nd for osteosynthesis

To evaluate the microstructure, mechanical properties, and degradation behaviour of a bioresorbable Mg-3.15Nd-1.25Zr-0.6Zn (wt.%) alloy produced via an industrially compatible route, and to demonstrate its superiority over the reference alloy ML10 for osteosynthesis applications with degradation synchronized to bone healing. Research methods. Microstructure was examined by optical microscopy (Neophot 32, OLYMPUS IX 70) and SEM/EDS (SELMI REM-106I). Grain size was measured by the intercept method (ISO 643:2024). Mechanical properties were determined on an INSTRON 2801 machine (ASTM B557, ISO 6892-1) in the heat-treated condition and after 90-day immersion in Gelofusine (pH 7.4), Venofundin (pH 5.5), and physiological saline at 36 ± 1 °C. Corrosion rates were obtained by gravimetric mass loss. Heat treatment was performed under argon in Bellevue and PAP-4M furnaces. Industrial trials were conducted on malleolar screws of three sizes at JSC “Motor Sich”. Results. After casting into a water-cooled copper mould (25–30 °C/s) and two-stage heat treatment (560 °C/8 h + 200 °C/16 h), the alloy exhibited a grain size of 57 ± 4.7 µm (50% finer than ML10), with clean boundaries containing dispersed Zn₂Zr₃ and β″ precipitates instead of continuous (Mg,Zn)₁₂Nd networks. Ultimate tensile strength reached 309 ± 6.5 MPa, yield strength 252 ± 6.5 MPa, and elongation 7.9 ± 0.65% – improvements of 31%, 33%, and 126% over ML10. Corrosion rates (0.45–0.68 mm/year) were 39–42% lower than ML10. After 90 days the alloy retained 58–76% of initial strength (182–230 MPa), maintaining >180 MPa throughout the critical 12-week healing period, versus 38–42% for ML10. Industrial trials on three screw sizes confirmed reproducibility. Scientific novelty. For the first time, a comprehensive evaluation of the interrelationship between microstructure, mechanical properties, and degradation kinetics of the Mg-3.15Nd-1.25Zr-0.6Zn alloy was performed across three model biological fluids with systematic benchmarking against ML10 and bone healing requirements. It was established that elimination of continuous (Mg,Zn)₁₂Nd grain-boundary networks combined with grain refinement to 57 µm shifts the dominant corrosion mode from catastrophic intergranular attack (150–200 µm penetration in ML10) to uniform surface corrosion (<50 µm penetration), yielding degradation kinetics temporally synchronized with the physiological stages of bone healing. Practical value. An industrially scalable route was validated in pilot production of malleolar screws using standard melting, copper-mould casting, and conventional heat treatment. The alloy provides a sufficient mechanical safety margin throughout all critical healing phases (weeks 0–20), surpassing ML10 and meeting preclinical requirements for biodegradable orthopaedic fixation.

Purpose. To develop a rational heat treatment regime for a new biodegradable magnesium alloy of the Mg-Zr-Nd system, to ensure enhanced mechanical properties throughout the entire treatment period. Research methods. Differential thermal analysis (DTA) was used to determine phase transformation temperatures. Microstructure analysis was conducted using optical microscopy (“Neophot 32” and “OLYMPUS IX 70”) and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SELMI RЕМ-106I). Mechanical properties were determined using an INSTRON 2801 testing machine. The influence of cooling rate on microstructure and properties was studied using ProCAST simulation software. Heat treatment was carried out in a Bellevue type shaft furnace and a PAP-4M furnace. X-ray analysis was used to detect internal defects in samples. Results. A new heat treatment regime was developed for the biodegradable Mg-3.15Nd-1.25Zr-0.6Zn (wt%) alloy. Using differential thermal analysis and microstructure studies at various quenching temperatures, the optimal quenching temperature was established at 560 °C. Empirical relationships describing the influence of heat treatment parameters on the alloy's microstructure were calculated. The new heat treatment regime (quenching from 560 °C for 8 hours, air cooling + aging at 200 °C for 16 hours) resulted in improved mechanical properties (UTS = 276–282 MPa, δ = 5.2–5.8%) compared to the standard T6 regime. Scientific novelty. For the first time, a comprehensive study of the influence of heat treatment parameters on the structure and properties of a new Mg-3.15Nd-1.25Zr-0.6Zn (wt%) alloy with increased content of alloying elements was conducted. New dependencies describing the influence of quenching temperature on the alloy's grain size were established. Practical value. A new heat treatment regime for the biodegradable magnesium alloy was developed, which ensures complete dissolution of the pseudoeutectic phase and formation of strengthening phases, resulting in improved mechanical properties compared to the standard alloy Mg-2.5Nd-0.4Zn-0.5Zr (wt%) and the standard T6 regime.