Phase equilibria and microstructure development in Mg-rich Mg-Gd-Sr alloys: Experiments and CALPHAD assessment

• Published in: Calphad Vol. 82; p. 102583
• Main Authors: Long, Qiang, Meng, Na, Chen, Fuwen, Zhang, Ligang, Tao, Xiaoma, Liu, Libin, Xu, Guanglong, Cui, Yuwen
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.09.2023
• Subjects: CALPHAD; First-principles calculations; Mg–Gd–Sr; Phase equilibria; Thermodynamic assessment; Phase equilibria; First-principles calculations; CALPHAD; Mg–Gd–Sr; Thermodynamic assessment
• ISSN: 0364-5916; 1873-2984
• DOI: 10.1016/j.calphad.2023.102583

Mg-Sr alloys are promising to fabricate orthopedic implants. The alloying of rare earth elements such as Gd may improve the comprehensive mechanical properties of Mg-Sr alloys. The information on the phase diagram and the microstructure development are required to design chemical composition and microstructure of Gd alloyed Mg-Sr alloys. The phase equilibria and the microstructure development in Mg-rich Mg-Gd-Sr alloys (Gd, Sr < 30 at. %) are experimentally investigated via phase identification, chemical analysis, and microstructure observation with respect to the annealed ternary alloys. The onset temperatures of liquid formation are measured by differential scanning calorimetry. A thermodynamic database of the Mg-rich Mg–Gd–Sr ternary system is developed for the first time via CALPHAD (CALculation of PHAse Diagram) approach assisted by First-Principles calculations. The thermodynamic calculations with the developed database enable a well reproduction of the experimental findings and the physical-metallurgical understanding of the microstructure formation in solidification and annealing.