Abstract A multi-step solution heat treatment regime of a Mo-rich Ni based single crystal superalloy (Alloy Mo) was designed, and the effect of each solution heat treatment step on microstructure, microsegregation degree and phase transformation characteristic temperatures of Alloy Mo was investigated by experimental analysis and dynamic calculation (via DICTRA). Homogenizations of microstructure and Re element in as-cast Alloy Mo were obtained via first step solution heat treatment (lowest temperature and shortest time) and last step solution heat treatment (highest temperature and longest time), respectively. In addition, appropriate diffusion length for dynamic calculation of homogenization of Re element was determined. Meanwhile, solution heat treatment increased the solidus temperature of as-cast Alloy Mo, while it had less effect on liquidus temperature and γ′ solvus temperature. Moreover, as compared with W-rich single crystal superalloys, effects of solution heat treatment on both solidus temperature and γ′ solvus temperature of Mo-rich single crystal superalloy were lower. Additionally, γ′ solvus temperatures of Mo-rich single crystal superalloys were lower than those of W-rich single crystal superalloys.

中文翻译：

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富钼第二代镍基单晶高温合金固溶热处理响应及γ′固溶线温度研究

摘要 设计了一种富钼镍基单晶高温合金（Mo合金）的多步固溶热处理方案，研究了各固溶热处理步骤对Mo合金显微组织、显微偏析度和相变特征温度的影响。通过实验分析和动态计算（通过 DICTRA）。通过第一步固溶热处理（最低温度和最短时间）和最后一步固溶热处理（最高温度和最长时间），分别获得铸态Mo合金组织和Re元素的均匀化。此外，还确定了用于动态计算 Re 元素均质化的适当扩散长度。同时，固溶热处理提高了铸态Mo合金的固相线温度，而对液相线温度和γ′固溶线温度的影响较小。此外，与富W单晶高温合金相比，固溶热处理对富Mo单晶高温合金固相线温度和γ'固溶线温度的影响较小。此外，富钼单晶高温合金的γ'固溶线温度低于富钨单晶高温合金。