添加稀土元素能有效改善镍基高温合金的多项性能，但其在熔炼过程中易烧损，导致收得率难以精确控制。本工作以添加稀土Sc元素的镍基变形高温合金BYG36为研究对象，从真空感应熔炼系统中可能存在烧损或挥发产物的6个位置取样，分析Sc元素的烧损位置和存在形式，明确Sc元素的烧损机制。结果表明，Sc主要残留在坩埚壁内侧残渣、坩埚上缘和流钢口残渣中，在观察镜、炉膛和冒口砖内表面均未检测到Sc元素存在。原子尺度分析结果表明，坩埚壁内侧残渣中的富Sc相为立方结构的Al_1.3Sc_0.7O₃而非正交结构的ScAlO₃，其很可能源于熔炼过程中Sc与坩埚内壁耐火材料中的Al₂O₃反应生成；坩埚上缘和流钢口残渣中的富Sc相为立方结构的Sc₂O₃，其可能源于熔炼过程中Sc元素与合金熔体中的O元素反应生成，在浇注过程中熔体流过坩埚上缘和流钢口时，由于靠近耐火材料处流速减慢，夹杂物沉淀挂壁在耐火材料表面。

Rare-earth elements significantly enhance key service performances of nickel-based superalloys. However, due to burning loss, the actual yield of rare-earth elements within the alloy is challenging to control precisely in practice. This study investigates the burning loss pathways of Sc during the melting and casting of a nickel-based superalloy BYG36. Samples were collected from six typical locations in the vacuum induction melting system where burning or volatilization products might be present. The samples were thoroughly characterized regarding Sc content, phases, morphology, and atomic-scale structures. While no Sc residue was found in the furnace ash, observation window, or entry nozzle—indicating minimal volatilization of Sc—a substantial amount of Sc was found adhering to the inner side surface of the crucible, the crucible rim, and the inner side surface of the sprue. Atomic-scale characterizations revealed that the Sc-rich phase on the inner surface of the crucible was a cubic-structured Al_1.3Sc_0.7O₃, in contrast to the previously assumed orthogonal-structured ScAlO₃. Intermingling with Al₂O₃ particles in the refractory materials, this cubic-structured phase likely formed through reactions of Sc with Al₂O₃ during the melting process. In contrast, Sc residue on the crucible rim and the inner side surface of the sprue was identified as cubic-structured Sc₂O₃ particles deposited directly on the refractory material surfaces. These inclusions originated from reactions of Sc with O in the alloy melt and adhered to the refractory surfaces as the melt slowly flowed over the crucible rim and sprue during casting.