中文摘要：

目前Nb基超高温合金的制备主要是通过多次电孤熔炼得到成分均匀的铸锭.其定向凝固或者是在水冷铜坩埚内采用Czochralski技术进行,或者是采用不需要坩埚的悬浮区熔法实现,但这两种方法都不能得到较高的温度梯度.为了获得更好的定向凝固组织,需要在超高温超高真空定向凝固设备上进行有坩埚的整体定向凝固.结合国内外共晶自生复合材料常用的制备技术,提出了适用于铌基超高温合金整体定向凝固技术的坩埚材料及其涂层技术.

英文摘要：

At present, niobium-based ultrahigh-temperature alloys are usually prepared by multiple arc-melting in order to get uniform as-cast ingots. Their directional solidification is carried out by either Czochralski technology in the water-cooled copper crucibles or floating zone method without crucible, but the temperature gradient is not high with these two methods. In order to obtain better directional solidification microstructure, the whole directional solidification technique needing crucibles should be adopted. Based on the common manufacturing technology of in-situ composites at domestic and abroad, the crucible materials and the coating technologies suitable for the whole directional solidification technique of niobium based ultrahigh temperature alloys are proposed.