强磁场下难混溶合金的液－液相变动力学及非平衡凝固研究

项目名称： 强磁场下难混溶合金的液－液相变动力学及非平衡凝固研究

项目编号： No.51271055

项目类型： 面上项目

立项/批准年度： 2013

项目学科： 一般工业技术

项目作者： 高建荣

作者单位： 东北大学

项目金额： 80万元

中文摘要： 难混溶合金具有重要的应用价值，但液相内的流动使常规条件下制备的合金铸锭往往存在严重的宏观偏析甚至分层现象。为了探索难混溶合金的凝固新工艺，需要对其在控制对流条件下的液－液和液－固相变过程特别是液－液相变动力学进行研究。本项目选择在液态下具有亚稳溶解度间隙的Cu-Co合金作为模型合金，采用熔融玻璃净化深过冷技术使其在中等冷却条件下发生液－液相变和快速凝固，并在冷却过程中采用匀强磁场和梯度强磁场施加的洛伦兹力和磁化力来分别控制液－液相变过程中基体相的对流和弥散相液滴的迁移。通过分析不同成分、过冷度和磁场条件下快速凝固合金中弥散相液滴的尺寸分布、化学成分和亚结构，结合元胞自动机模拟，揭示控制对流条件下液－液相变过程中弥散相液滴的形核、长大、粗化动力学及非平衡凝固特性。项目的研究结果对于全面认识难混溶合金的液－液和液－固相变过程具有重要的理论意义，并可为难混溶合金凝固新工艺的探索提供思路和手段。

中文关键词： 难混溶合金；强磁场；液液相变；非平衡凝固；数值模拟

英文摘要： Immiscible alloys have important applications. But, liquid flow often causes serious macrosegregation and even layering under ordinary casting conditions. In order to explore a novel casting technology with medium cooling, liquid-liquid and liquid-solid phase transformations, especially the liquid-liquid transformation kinetics, need to be investigated by controlling liquid flow. For this purpose, the binary Cu-Co system with a metastable liquid miscibility gap in the undercooled region is chosen as a model system in the present proposal. Bulk alloy samples are undercooled, decomposed in the liquid state and rapidly solidified by glass-fluxing treatment under medium cooling conditions. A high uniform magnetic field and a high gradient magnetic field are imposed on the samples to exert a large Lorentz force and a large magnetization force for controlling liquid flow of the matrix phase and migration of dispersed droplets during the liquid-liquid transformation process, respectively. Size distribution, chemical composition and substructures of the dispersed droplets are investigated as functions of alloy composition, bulk undercooling prior to solidification, intensity and gradient of the imposed magnetic fields. The nucleation, growth and coarsening kinetics of the dispersed droplets during the liquid-liquid tran

英文关键词： Immiscible alloys；High magnetic fields；Liquid-to-Liquid transition；Non-equilibrium solidification；Numerical simulation