在工业生产中，包晶合金体系占据着重要地位，关于其亚稳凝固机理、组织调控及应用性质的研究一直是个热点课题。自然界中关于包晶型合金的材料主要分为两大类，一种是普通的包晶型合金，另一种是容易发生亚稳液相分离的包晶型合金。本文选择普通的Si-Ni包晶型合金以及容易发生亚稳液相分离的Fe-Cu包晶型合金作为研究对象，主要开展了以下三方面的研究。

     （1）本文采用熔体浸浮和电弧熔炼技术研究了快速凝固Si_66.7Ni_33.3合金的亚稳凝固机理和微观力学性能。结果表明快速凝固组织由Si固溶体、NiSi₂和NiSi金属间化合物相组成。随过冷度增加，初生Si相生长加快，形貌由片状向枝晶转变，尺寸减小；包晶反应加剧，NiSi₂相变窄。过冷达123 K时，NiSi₂生长速度突增，共晶形态由规则向非规则转变，显微硬度骤降。Ni在NiSi₂和NiSi相中的固溶度随过冷度线性增加，呈现溶质截留现象。电弧熔炼样品 (8 mm) 组织为初生Si、包晶NiSi₂和共晶 (NiSi+NiSi₂) 相，过冷度和硬度随距底部距离减小而降低；样品直径减至2 mm时，NiSi₂相直接从底部形核，其余组织与8 mm样品相似。

     （2）本文结合熔体浸浮实验与X射线断层扫描技术，研究了过冷Si-Ni包晶合金的三维组织演变。结果表明凝固组织由初生Si相、包晶NiSi₂相及枝晶间共晶 (NiSi+NiSi₂) 相组成。随过冷度增加，片状Si相和NiSi₂相增多，但Si相最大尺寸方向收缩，而包晶相三维增厚。过冷度超过阈值后，共晶由规则片层向非规则转变，体积分数降低且组织细化。由于Si相上浮效应，样品上部初生Si和NiSi₂相增多，共晶相减少；外壳区域因过冷度较高，片状Si相较样品中心更短，共晶相更少。

     （3）本文采用熔体浸浮技术研究了电磁搅拌对过冷Fe₇₅Cu₂₅合金凝固及耐蚀性的影响。结果表明当过冷度小于160K时，合金以包晶方式凝固；过冷度大于160K时则发生亚稳液相分离，形成弥散或核-壳组织。深过冷促使晶粒细化，αFe相增多且Cu含量增加。电磁搅拌可细化组织，减少αFe相。合金腐蚀以点蚀为主，未发生相分离时，过冷度增大和电磁搅拌均可提升耐蚀性；但电磁搅拌导致的宏观偏析会降低耐蚀性。耐蚀性能与初生相含量、晶粒尺寸及溶质浓度密切相关。

      In industrial production, peritectic alloy systems play a pivotal role, and research on their metastable solidification mechanisms, microstructure control, and application properties has consistently been a hot topic. In nature, materials related to peritectic alloys are primarily divided into two categories: ordinary peritectic alloys and those prone to metastable liquid phase separation. This paper selects ordinary Si-Ni peritectic alloys and Fe-Cu peritectic alloys, which are susceptible to metastable liquid phase separation, as the research subjects, focusing on the following three aspects of study.

   （1）This article investigates the metastable solidification mechanism and micro mechanical properties of rapidly solidified Si_66.7Ni_33.3 alloy using melt immersion and arc melting techniques. The results indicate that the rapidly solidified microstructure is composed of Si solid solution, NiSi₂ , and NiSi intermetallic compound phases. With the increase of undercooling, the growth of primary Si phase accelerates, the morphology changes from flake to dendrite, and the size decreases; The crystallization reaction intensifies and the NiSi₂ phase transition becomes narrow. When undercooled to 123 K, the growth rate of NiSi₂ suddenly increases, the eutectic morphology changes from regular to irregular, and the microhardness drops sharply. The solid solubility of Ni in NiSi₂ and NiSi phases increases linearly with undercooling, exhibiting solute retention phenomenon. The microstructure of the arc melted sample (8 mm) consists of primary Si, pericrystalline NiSi₂, and eutectic (NiSi+NiSi₂) phases. The undercooling and hardness decrease with decreasing distance from the bottom; When the sample diameter is reduced to 2 mm, NiSi₂ phase nucleates directly from the bottom, while the rest of the tissue is similar to the 8 mm sample.

    （2）This article combines melt immersion experiments and X-ray tomography technology to study the three-dimensional microstructure evolution of undercooled Si Ni eutectic alloys. The results indicate that the solidified structure is composed of primary Si phase, pericrystalline NiSi₂ phase, and interdendritic eutectic (NiSi+NiSi₂) phase. With the increase of undercooling, the number of sheet-like Si phase and NiSi₂ phase increases, but the maximum size direction of Si phase shrinks, while the three-dimensional thickness of eutectic phase thickens. After the undercooling exceeds the threshold, the eutectic transforms from regular lamellar to irregular, the volume fraction decreases, and the microstructure becomes finer. Due to the upward floating effect of Si phase, the number of primary Si and NiSi₂ phases in the upper part of the sample increases, while the eutectic phase decreases. The shell area has a higher degree of undercooling, resulting in shorter sheet-like Si and fewer eutectic phases compared to the center of the sample.

    （3）This article uses melt immersion technology to study the effect of electromagnetic stirring on the solidification and corrosion resistance of undercooled Fe₇₅Cu₂₅ alloy. The results indicate that when the undercooling is less than 160K, the alloy solidifies in a transgranular manner; When the undercooling exceeds 160K, metastable liquid phase separation occurs, forming dispersed or core-shell structures. Deep undercooling promotes grain refinement, an increase in αFe phase, and an increase in Cu content. Electromagnetic stirring can refine the structure and reduce the αFe phase. The corrosion of alloys is mainly pitting corrosion. When phase separation does not occur, increasing undercooling and electromagnetic stirring can improve corrosion resistance. However, the macroscopic segregation caused by electromagnetic stirring will reduce the corrosion resistance. The corrosion resistance is closely related to the content of primary phases, grain size, and solute concentration.

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