中文摘要：

采用真空非自耗电弧熔炼然后真空自耗电弧熔炼的方法制备了Nb-Cr系多元合金的母合金锭,在超高温高真空热处理炉上进行了1250℃,24h;1350℃,24h和1450℃,24h的高温热处理。通过X射线衍射、光学金相、扫描电子显微镜和能谱分析等手段对材料的电弧熔炼态组织和热处理后组织进行了观察和研究。结果表明：电弧熔炼态组织由树枝晶的Nbss基体和枝晶间均匀分布的Laves相Cr2（Nb,Ti,Hf）块组成;热处理后,组织细化,Nbss树枝晶全部转变为等轴晶组织。随着热处理温度的升高,组织更加细化,组成相中Cr化物相含量增加。

英文摘要：

A master alloy ingot of Nb-Cr based multi-element alloy has been prepared by a vacuum non-consumable arc-melting and then a vacuum consumable arc-melting. The samples are then heat treated at 1250 ℃/24 h, 1350 ℃/24 h and 1450 ℃/24 h, respectively. Both the arc-melted microstructure and the heat-treated microstructure are characterized by using X-ray diffractometer, optical microscope （OM） and scanning electron microscope （SEM） equipped with energy dispersive spectrum analyzer （EDS）. The results show that the arc-melted microstructure was composed of Nb solid solution （Nbss） dendrites and Laves Cr2（Nb, Ti, Hf） blocks dispersed in the Nbss dendrite intervals; after heat treatments, the phase constituents of alloy are same as those in the arc-melted microstructure. However, the microstructure is refined, and the Nbss dendrites disappeare and are transformed into equiaxed crystals. Furthermore, the fine and dispersed secondary Cr2（Nb, Ti, Hf） are precipitated in the Nbss matrix. With the increase of heat treatment temperature, the microstructure became finer, and the amount of Cr2（Nb, Ti, Hf） increases.