钴基合金具有高耐热蚀性、优异的抗疲劳和抗氧化性，被广泛应用于航空航天和生物医学领域。为研究深过冷与快速凝固对合金晶体生长和微观力学性能的作用机制，本工作采用静电悬浮技术实现了Co35Ti35Nb30合金的深过冷与快速凝固，并结合纳米压痕方法对合金的抗蠕变性能进行了研究。合金的近平衡凝固组织为层片Co(Ti,Nb) + (Nb)共晶，这两相取向关系为{110}Co(Ti,Nb) // {110}(Nb) 和 <-113>Co(Ti,Nb) // <-113>(Nb)。在静电悬浮条件下，归因于共晶中两相的独立形核与竞争生长，合金微观组织随过冷度提升由层片共晶转变为不规则共晶。当过冷度达到273 K时，两相不再保持特定取向关系。由于过冷度增加引起的溶质截留效应和组织细化，合金维氏硬度和抗蠕变性能显著提升。随着过冷度从30 K增加至273 K，合金维氏硬度提升26.1 %，同一加载应变率下稳态蠕变阶段的蠕变应变率下降72.9 %。通过计算蠕变应力指数和活化体积，分析了合金的纳米压痕蠕变行为和机理。该合金的蠕变行为以位错运动为主，对加载应变率变化灵敏度低，在稳态蠕变阶段变形速率随加载应变率变化较小。

Cobalt alloys, a series of high-temperature alloys with high thermal corrosion resistance, excellent fatigue resistance and oxidation resistance, have been commonly used as structural materials in the recent decades, especially in aerospace engineering and biomedical fields. In experimental, a sample was levitated between two vertical electrodes coupled with four side electrodes in a chamber evacuated to 1.0 × 10-5 Pa. When the levitated sample was heated and melted for several times by SPI SP300 laser, it solidified rapidly at high undercooling owing to the high-vacuum environment and containerless state. The rapid solidification mechanism and micromechanical properties of ternary Co35Ti35Nb30 alloy were investigated by means of electrostatic levitation (ESL). The microstructure of the alloy consists of Co(Ti,Nb) + (Nb) eutectic. An orientation relationship of {110}Co(Ti,Nb) // {110}(Nb) and <-113>Co(Ti,Nb) // <-113>(Nb) formed between Co(Ti,Nb) and (Nb) phases. Under ESL conditions, the microstructure transformed from lamellar to anomalous eutectic with increasing undercooling. The microstructure of the alloy underwent a transformation into a completely anomalous eutectic and had no crystallographic orientation relationship because of the independent growth of the two phases, at the maximum undercooling (273 K). The nanoindentation creep behavior and mechanism were analyzed by estimating the strain rate sensitivity and activation volume. Owing to the refinement of the rapidly solidified microstructure and the Ti solute trapping in the (Nb) phase, the resistance to dislocation motion of the alloy increased, and the microhardness and creep resistance of the alloy improved. With the undercooling increased from 30 to 273 K, the creep strain rate during the steady stage creep stage decreased by about an order of magnitude, from 1.03 × 10-4 s-1 to 2.79 × 10-5 s-1. In addition, increasing the loading strain rate promoted the proliferation of dislocations during loading, leading to an increase in strain rate sensitivity from 7.7 × 10-5 to 8.7 × 10-5 and a decrease in activation volume from 26.7 b3 to 25.7 b3.