Cu/Al复合带固-液铸轧电流强化复合成形技术基础研究

Cast rolling cladding is a new energy-saving technology developped in recent years. It combines the rapid solidification with roll bonding, realizing the green production of bimetallic laminar composite material with high efficiency and in short process. In order to resolve the clading strip manufacturing between two high different melt point metals, aiming at of Cu/Al clad strip, a new forming technology of solid-liquid cast rolling with pulse electric current strengthening was put forward in this project. In order to investigate the core scientific problems such as the complex thermodynamic behaviors, interface reactive diffusion mechanism, residual stress control for the new forming process. A physical simulation experiment device was independently developed to study the influence law and strengthening mechanism of the pulse current on the wettability and reactive diffusion of Cu/Al solid-liquid metal interface at different temperature. By combining the finite element method and molecular dynamics with the theory of diffusive transformation, the thermodynamic and dynamic model and the multi-scale quality predictive control model for the growth of the bonding interface are established. According to the asymmetric thermal boundary and deformation system, the differential speed rolling was adopted and the control strategy and influence law of rolling parameters on the interface bonding strength, metal flow, warping defects and residual stress was investigated. Through the structure and function transformation of an existing twin roll caster, the best structure and process parameters was determined by combining the theoretical model with the prototype experiment. This study has important theory significance and practical application value in improving the forming technology level of bimetallic clad strip in short process assisted with high energy field.

铸轧复合成形工艺是近年来发展的一项节能新技术，它将快速凝固和轧制复合相结合，实现双金属层状复合材料的短流程、高效绿色生产。为解决大差异熔点金属复合带高效制备问题，本课题以Cu/Al复合带为对象，提出一种固-液铸轧电流强化复合新工艺，并围绕其热力学行为、界面反应扩散机制和残余应力控制等基础科学问题，研究脉冲电流对Cu/Al固-液金属润湿和界面反应扩散的影响规律和强化机理。将有限元方法、分子动力学和扩散相变原理相结合，建立界面反应扩散层生长热力学、动力学多尺度预测控制模型。研究非对称边界和形变系统下异步铸轧对界面结合强度、金属流动、翘曲缺陷和残余应力的影响规律和控制策略。通过对实验室现有双辊铸轧机的结构功能改造，将理论模型与样机实验相结合，综合考虑界面复合质量和尺寸形状精度，确定最佳设备结构与工艺参数。本项研究对提高双金属复合带的外场辅助短流程制备技术水平具有重要理论意义和实际应用价值。

本课题围绕Cu/Al复合材料固-液铸轧工艺中的复杂热力学行为、界面复合质量和残余应力控制等核心科学问题，通过理论建模、数值模拟与实验分析，取得了如下研究进展：.（1）建立了Cu/Al固-液铸轧复合热−流耦合数值仿真模型，模拟分析了浇注温度、熔池高度、轧辊直径、冷却条件、铸轧速度、铜带及复合带材厚度等工艺参数对复合界面热力学行为及铝液凝固其微观组织的影响规律，确定了合理的工艺参数匹配关系。.（2）自主研制了双金属层状复合板异温电流强化复合工艺物理模拟装置，利用高温Cu带与Al带强压接触传热及其产生的铝带表面浅层熔化现象，提出一种基于界面“局部熔合”的双辊异温铸轧复合工艺，并通过数值仿真与物理模拟，给出了实现界面熔合的工艺条件。.（3）搭建了电脉冲强化Cu/Al固-液复合物理模拟模型，研究了不同温度下脉冲电流参数对Cu/Al界面反应及扩散层厚度的影响规律，初步探明界面原子在反应扩散、原子风和电场共同驱动下迁移并最终影响扩散层厚度的物理现象。.（4）建立了固-液铸轧复合界面温度-形变耦合有限元模型，将有限元方法、分子动力学和扩散相变原理相结合，模拟分析了Cu/Al复合界面反应扩散生长的热力学、动力学多尺度耦合行为。.（5）通过分析铸轧变形区内复合界面微观形貌和物相组成的动态演变，阐释了Cu/Al固-液铸轧复合的宏微观机制，发现固相区轧制压下及延伸变形对界面结合强度的重要影响，提出通过合理设置KISS点高度进行界面性能调控的指导性策略。.（6）引入生死单元法，建立了Cu/Al固-液铸轧复合成形过程非线性有限元模型，模拟分析了工艺参数对Cu/Al复合带应变场、应力场、温度场的影响规律，揭示了异步铸轧对金属流动、翘曲缺陷和残余应力的影响规律，提出了改善残余应力的工艺控制策略。.本课题是传统铸轧工艺与轧制复合技术的有机融合，解决了固-液铸轧复合成形工艺开发中的关键科学与技术问题，为实现双金属层状复合材料短流程制备提供了新途径，并已成功应用于新材料开发，应用前景广阔。