The phase equilibria of the Ho-Zr-Si ternary system were experimentally determined at 973 K (700 °C) in the entire concentration range by using powder X-ray diffraction (XRD), scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDS), and differential scanning calorimetry (DSC). The results show that there are 13 single-phase regions, 23 two-phase regions, and 11 three-phase regions in the investigated isothermal section, and no ternary compound is found. The composition ranges of all phases are extremely small. Among these, there are ten extensions of the binary compounds, i.e., ZrSi2, α-ZrSi, α-Zr5Si4, Zr3Si2, Zr2Si, β-HoSi2-a, α-HoSi2-b, HoSi, Ho5Si4, and Ho5Si3, in the ternary system. They are Zr1–xHoxSi2 (x ≤ 0.084), α-Zr1–xHoxSi (x ≤ 0.156), α-Zr5–xHoxSi4 (x ≤ 0.945), Zr3–xHoxSi2 (x ≤ 0.550), Zr2–xHoxSi (x ≤ 0.180), β-Ho1–xZrxSi2–a (x ≤ 0.124), α-Ho1–xZrxSi2–b (x ≤ 0.147), Ho1–xZrxSi (x ≤ 0.220), Ho5–xZrxSi4 (x ≤ 1.368), and Ho5–xZrxSi3 (x ≤ 0.592), respectively. In the present work, the phase transformation temperatures of β-HoSi2-b → α-HoSi2–b and Ho3Si4 → β-HoSi2–b + HoSi are determined to be 979.7 K (706.7 °C) and 1479.3 K (1206.3 °C), respectively, by analyzing the DSC results.
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This research work is jointly supported by the National Natural Science Foundation of China (Grant No. 51761002), the National Key R&D Program of China (Grant No. 2016YFB0301400), the Training Plan of High-Level Talents of Guangxi University (Grant No. XMPZ160714), and the research project of Guangxi Key Laboratory of Processing for Non-ferrous Metallic and Featured Materials (Grant No. GXYSSF1807).