Thermodynamic description of the Dy–Si–C system in silicon carbide ceramics. (March 2020)

• Record Type: Journal Article
• Authors: Xu, Kai; Chen, Leilei; Chang, Keke; Wan, Peng; Li, Mian; Deng, Zixuan; Huang, Feng; Huang, Qing
• Is Part Of: Calphad. Volume 68(2020)
• Publication Date: 2020-03
• Subjects: Dy3Si2C2 -- Silicon carbide ceramics -- Phase diagram -- CALPHAD -- First-principles calculations; Phase diagrams -- Data processing -- Periodicals; Thermochemistry -- Data processing -- Periodicals; Diagrammes de phases -- Informatique -- Périodiques; Thermochimie -- Informatique -- Périodiques; Thermodynamica; Electronic journals; 541.363
• DOI: 10.1016/j.calphad.2020.101738
• Languages: English
• ISSNs: 0364-5916

Abstract

Abstract: To predict the thermal behaviors of Dy3 Si2 C2 during sintering or joining process of the silicon carbide (SiC) ceramics, we established a detailed thermodynamic description of Dy–Si–C by coupling the first-principles calculations and the CALPHAD (CALculation of PHAse Diagram) approach. First-principles calculations were applied to acquire the formation enthalpies of key compounds, which can perform as end-members during optimization. We proposed a first Dy–C binary phase diagram referred to other RE-C (RE = La, Ce and Pr) systems. The Dy–Si system, previously described with the modified quasichemical model (MQM), was modeled based on the random-mixing Bragg Williams model in this work. The presently obtained thermodynamic parameters can reasonably reproduce the available experimental data and elucidate the thermal behaviors of Dy3 Si2 C2 . We calculated that Dy3 Si2 C2 reacted with SiC via ternary eutectic reaction at 1432 °C, which was consistent with the reported experimental results. Further work of other SiC-based systems may provide foresight to explore new sintering aids in ceramics. Highlights: A first Dy–C binary phase diagram is proposed. Formation enthalpies are computed via CALPHAD and first-principles calculations. Dy3 Si2 C2 reacts with SiC via eutectic reaction: L⇌(C)+SiC + Dy3 Si2 C2 at 1432.6 °C. Complete liquidus projection and scheil reaction scheme are present in this work. Thermodynamic database can guide the sintering or joining process in SiC ceramics.