Thermodynamic analysis and investigation of phase evolution in the Mg–Ni–Ce system obtained by mechanical alloying and spark plasma sintering

Nuriya M. Arman M. Igor S. Zhanna O. Gulzhaz U. Aisara S. Ospan О. Balzhan B.
13 March 2026 Elsevier Ltd

International Journal of Hydrogen Energy
2026 #217

A comprehensive thermodynamic and kinetic modeling, as well as an experimental investigation, was carried out for the Mg–Ni–Ce system aimed at applications as solid-state hydrogen storage materials. Based on CALPHAD calculations in Thermo-Calc for compositions Mg85Ni10Ce5, Mg90Ni7Ce3, and Mg95Ni3Ce2 in the temperature range of 450–500 °C, isothermal sections of the phase diagram of the Mg–Ni–Ce system were constructed, equilibrium phase regions were determined, and the optimal conditions for the formation of hydride-active intermetallics Mg₂Ni and Mg₁₂Ce phases were predicted. Diffusion modeling in DICTRA showed limited mutual diffusion depths (<30 nm) over 180 s at 480 °C and a pronounced asymmetry of the Matano plane, caused by differences in the self-diffusion coefficients of Mg, Ni, and Ce. Experimentally, powders with the composition Mg90Ni7Ce3 were prepared by mechanical alloying at different ball-to-powder mass ratios (BPR = 10:1 and 30:1), followed by spark plasma sintering (SPS) at 500–560 °C, 1 MPa, for 5 min. X-ray diffraction (XRD) analysis revealed the sequential formation of Mg₂Ni and Ce–Mg phases during milling, accompanied by defect accumulation and distortion of the Mg crystal lattice. The intermetallic phase Ce₂Mg₁₇, absent after mechanical alloying, was detected only after SPS in the 480-500 °C range, indicating enhanced interaction between Ce and Ni under pulsed heating. Comparison of the calculated phase diagrams with the experimentally observed phase evolution highlighted Mg-rich compositions near Mg95Ni3Ce2 and the temperature range of 480–500 °C as the optimal compromise between the thermodynamic stability of Mg₂Ni. Mg₁₂Ce intermetallics and controlled phase densification. The results provide a thermodynamically grounded approach to designing Mg–Ni–Ce systems for hydrogen storage and establish a basis for further studies on sorption–desorption behavior and cyclic stability within the selected compositional range.

CALPHAD , DICTRA , Hydrogen storage , Intermetallics , Magnesium hydrides , Mechanical alloying , Mg–Ni–Ce alloys , Spark plasma sintering , Thermo-calc

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Institute of Atomic Energy Branch of the National Nuclear Center of the Republic of Kazakhstan, 10 Beybit Atom str., Kurchatov, 071100, Kazakhstan
Shakarim University, 20 Glinki st., Semey, 071412, Kazakhstan
D. Serikbayev East Kazakhstan Technical University, D. Serikbayev STR., 19, Ust-Kamenogorsk, 070004, Kazakhstan

Institute of Atomic Energy Branch of the National Nuclear Center of the Republic of Kazakhstan
Shakarim University
D. Serikbayev East Kazakhstan Technical University

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