Abstract Stability of lamellar structure of directionally solidified NiAl-28Cr-6Mo eutectic alloys was investigated at different withdrawal rates and temperatures. The result indicates that the lamellar structure has no significant change after various temperatures (900–1100 °C) at 2.5 μm/s. With increasing the withdrawal rate to 4.5 μm/s or 7.5 μm/s, no major change occurs in the lamellar structure at the temperature of up to 1000 °C, however, some little coarsening and migration of lamellar structure emerge at 1050 °C and 1100 °C. With increasing the withdrawal rate (decreasing the lamellar spacing), the stability of lamellar structure becomes poor. At the present experimental temperature (900–1100 °C, in particular, 1050 °C and 1100 °C), the migration, pinching off, coarsening, even spheroidization of Cr(Mo) phase are observed by mild etching. The deep etching and the observation of inclining 45° to growth direction improve the result about the pinching off and spheroidization of Cr(Mo) phase observed by mild etching. Actually, the local dissolution and the cylinderization of Cr(Mo) phase occur. The mechanism of lamellar degradation is discussed.

中文翻译：

---

定向凝固NiAl-28Cr-6Mo共晶合金在不同拉拔速率和温度下层状结构的稳定性

摘要 研究了定向凝固NiAl-28Cr-6Mo共晶合金在不同拉拔速率和温度下层状结构的稳定性。结果表明，层状结构在 2.5 μm/s 的各种温度（900-1100 °C）后没有显着变化。随着提取速率提高到 4.5 μm/s 或 7.5 μm/s，在高达 1000 °C 的温度下层状结构没有发生大的变化，但在 1050 °C 时出现了一些轻微的层状结构粗化和迁移，并且1100℃。随着提取率的增加（层间距减小），层状结构的稳定性变差。在目前的实验温度（900-1100°C，特别是 1050°C 和 1100°C）下，通过温和蚀刻观察到 Cr(Mo) 相的迁移、夹断、粗化甚至球化。深度蚀刻和与生长方向倾斜45°的观察改善了温和蚀刻观察到的Cr（Mo）相夹断和球化的结果。实际上，发生了 Cr(Mo) 相的局部溶解和圆柱化。讨论了层状降解的机制。