(河南工程学院 机械工程学院，郑州 451191)
摘 要: Hf-Sb二元系作为热电材料Half-Heusler合金的重要组元，因Hf(2227 ℃)与Sb(630 ℃)熔点相差1597 ℃，为Hf-Sb二元相图的测定带来极大困难。本研究采用螺纹密封在室温下制成固-液Hf-Sb二元扩散偶，在750~950 ℃五个温度点恒温退火14 d，获得了五组扩散偶样品，并对其进行了相平衡组织分析和成分测定。结果表明：经电子探针组织观察和成分分析，发现了严格计量比化合物HfSb2、有溶解度范围的(HfSb)和固溶体相(Hf)三个平衡相，获得了相应温度下的Hf-Sb二元系的相平衡关系和共轭平衡成分。其中，化合物(HfSb)成分范围为48.41%~52.23% Sb，随着温度的增高，Hf-Sb互溶范围有扩大趋势；化合物HfSb2高温下不稳定，在900 ℃以上发生偏晶分解。
关键字: Hf-Sb二元系；扩散偶；相平衡；相图
（School of Mechanical Engineering, Henan University of Engineering, Zhengzhou 451191, China）
Abstract:As an important component of thermoelectric Half-Heusler alloys, the melting point difference between Hf(2227 ℃) and Sb(630 ℃) is 1597 ℃, which makes it very difficult to build the Hf-Sb binary phase diagram. In this work, the solid-liquid Hf-Sb binary diffusion couples were fabricated by screw seal at room temperature. After annealing at five temperature points from 750 ℃ to 950 ℃ for 14 d, five groups of diffusion couple samples were obtained, and their phase equilibrium structure and composition were analyzed. The results show that three equilibrium phases, strictly stoichiometric compound HfSb2, (HfSb) with solubility range and solid solution (Hf), are found, the phase equilibrium relationship and the conjugate equilibrium compositions of Hf-Sb binary system at corresponding temperature were obtained by electron probe microanalysis (EPMA). The composition range of (HfSb) compound is 48.41%-52.23% Sb, the mutual solubility range of Hf-Sb tends to expand with the increase of temperature. The compound HfSb2 is unstable at high temperature and undergo monotectic decomposition above 900 ℃.
Key words: Hf-Sb binary system; diffusion couple; phase equilibrium; phase diagram
