Thermodynamic Assessment of the Mg–Ni–Si System

• Published in: Powder metallurgy and metal ceramics 2020-07, Vol.59 (3-4), p.209-223
• Main Authors: Zeng, Yinping, Dreval, L.O., Dovbenko, O.I., Du, Yong, Liu, Shuhong, Hu, Biao, Agraval, P.G., Turchanin, M.A.
• Format: Article
• Language: English
• Subjects: Analysis; Ceramics; Characterization and Evaluation of Materials; Chemistry and Materials Science; Composites; Computer simulation; Glass; Homogeneity; Intermetallic compounds; Intermetallic phases; Invariants; Liquidus; Literature reviews; Magnesium compounds; Materials Science; Mathematical models; Metal silicides; Metallic Materials; Natural Materials; Nickel silicide; Peritectic reactions; Phase diagrams; Physicochemical Materials Research; Polynomials; Silicon; Ternary systems; Thermodynamics
• ISSN: 1068-1302; 1573-9066
• DOI: 10.1007/s11106-020-00153-6

The thermodynamic assessment of the Mg–Ni–Si system has been developed in the framework of the CALPHAD method. The critical review of the literature data has been provided. A set of selfconsistent thermodynamic parameters for the phases in this ternary system is obtained using the phase diagram data available in the literature. The excess Gibbs energy term of solution phases is described using the Redlich–Kister polynomial. The sublattice model is used to describe the MgNi 2 intermetallic phase having homogeneity range in the ternary system. Ternary intermetallic compounds are modelled as line compounds. Isothermal sections and liquidus surface, as well as the coordinates of the invariant reactions, are calculated. The calculated results are in satisfactory agreement with the experimental data. The calculated liquidus surface is extremely complex and contains 38 invariant reactions including 8 degenerated reactions and 10 invariant maxima. Most of the presented invariant reactions must be considered as approximate. The τ 3 and τ 5 phases melt congruently at 1544 and 1487 K, respectively. The τ 4 forms via the peritectoid τ 5 + NiSi + βNi 2 Si ↔ τ 4 reaction at a temperature of 1193 K. According to our calculations, τ 1 and τ 8 melt at 1359 K (the L + τ 5 ↔ τ 1 reaction) and 1267 K (the L + τ 1 ↔ τ 8 reaction). The τ 2 and τ 6 are formed via the peritectic reactions at 1317 K (the L + τ 3 + MgNi 2 ↔ τ 2 reaction) and at 1229 K (the L + τ 5 + Mg 2 Si ↔ τ 6 reaction), and the τ 7 is formed via peritectoid Mg 2 Si + τ 1 + τ 5 ↔ τ 7 reaction at 1279 K.