共晶合金在工业生产中应用非常广泛，尤其是亚共晶和过共晶成分合金，此类合金凝固中包含初生相析出和共晶相转变两个密切关联的过程。以往凝固理论研究大都基于共晶成分合金，未考虑初生相的影响，其成果无法直接用于非共晶成分合金，致使共晶合金凝固理论长期进展缓慢。本项目主要通过深过冷快速凝固等技术研究非共晶成分合金的凝固界面形态、迁移速率随过冷度的变化关系，采用大过冷度快淬技术，研究合金成分和两个转变过冷度对此类合金的非平衡共晶转变过程影响，探索该合金凝固过程的片层共晶和非规则共晶组织的形成机制，并建立相关物理模型。该研究能深入揭示非共晶成分合金的非平衡凝固机理，拓展共晶凝固理论，促进多元多相合金凝固理论的发展。

Eutectic alloys, especially for hypoeutectic and hypereutectic alloys, are widely used in industrial productions. Solidifications of hypoeutectic and hypereutectic alloys include two closely related transitions, i.e. primary and eutectic solidifications. However, the classical solidification theory mainly focused on the alloy with eutectic composition, without considering the primary solidification, so that the theories cannot be applied to the off-eutectic alloys, and thus leading to the lack of progress in eutectic solidification theory over a long period. On this basis, this project will mainly investigate the evolutions of the morphology and growth velocity of solidification interface as a function of undercooling by means of high undercooling and rapid solidification method. And then by fast-quench at a large undercooling, the effects of the alloy composition and two undercoolings(for primary and eutectic solidifications) on non-equilibrium eutectic transition of the off-eutectic alloys will be studied. Meanwhile, the mechanisms and models of lamellar eutectic and anomalous eutectic will be explored. The study will reveal the non-equilibrium solidification mechanisms of off-eutectic alloys in depth, and improve the theory of eutectic and multi-phase solidification in polycrystalline materials.