RARE-EARTH ADDITIONS AND AGING EFFECTS ON AZ31 MAGNESIUM ALLOY: MICROSTRUCTURE, CORROSION, AND WEAR

• Sarah Khazaal Jabbar Madhi

  Department of Metallurgical and Materials Engineering, Al-Turath University, Baghdad, Iraq

  Author

Magnesium alloys are promising biodegradable orthopedic implant candidates due to their bone-compatible elastic modulus and density, but suffer from rapid corrosion in physiological media. This study investigates the combined effect of minor rare-earth (Nd, La) additions and isothermal aging at 180 °C on the microstructure, mechanical properties, wear, and electrochemical corrosion behavior of AZ31 magnesium alloy in 3.5 wt.% NaCl and simulated body fluid (SBF). Four compositions were produced by low-pressure permanent-mold casting and aged from 10 min to 3 h. Rare-earth additions promoted fine Al₁₁La₃, Al₂La, and Al-Nd intermetallics along grain boundaries. The optimized AZ31-0.5Nd-0.5La alloy aged 3 h achieved a 39% increase in Vickers hardness (56→78 HV), compressive yield strength of 148 MPa, and a corrosion current density of 1.14 μA/cm² in NaCl (87% reduction vs. as-cast AZ31). The highest polarization resistance (≈24.6 kΩ·cm²) was recorded in SBF. Bio-tribocorrosion synergy elevated wear rates in biological media despite reduced friction coefficients. These results position AZ31-0.5Nd-0.5La aged 3 h as a promising candidate for biodegradable orthopedic applications, pending in vitro and in vivo biological validation.

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