基于铝热还原-高频感应精炼制备均质CuCr难混溶合金的基础研究

The copper chromium alloy has become the preferred material for high power vacuum switch contact materials, which is of high breaking capacity，good overvoltage withstanding，anti-welding abilities，low chopping current，etc. But as a typical immiscible alloy，the method for preparing of large-sized, Ultra-Fine Grain, homogeneous copper chromium alloy has been no breakthrough. This application start from the new idea of preparing of large-sized, Ultra-Fine Grain, homogeneous Cu-Cr alloy, the new method for large-sized and homogeneous Cu-Cr immiscible alloy prepared by aluminum thermal reduction-high frequency induction refining has been proposed. First, using copper oxide and chromium oxide as raw materials, preparing of mutually dissolvable high temperature melt by thermit reduction-SHS(self-propagating high-temperature synthesis); then, refining and conditioning in the high-frequency magnetic field; finally, getting large-sized and homogeneous Cu-Cr alloy ingot by using “liquid-gas combined cooling” to rapid solidification. By reaching to the effects of different magnetic field intensity, crucible material and compound cooling system on the alloy chemical composition, micro fine structure(morphology, grain size and distribution) and density, it will clarify that the transfer rule and transfer mechanism of the slag-metal interface in the process of thermit reduction-SHS, electromagnetic induction refining, rapid cooling; and the system of precipitation, growth and separation of the second phase will also be illustrated. It will invent a new preparation technology with independent intellectual property rights of large-sized, Ultra-Fine Grain, homogeneous copper chromium alloy.

CuCr合金因具有开断能力大、耐电压能力强、抗熔焊能力好、截流水平低等优点，已成为大功率真空开关触头材料的首选。但作为一种典型的难混溶合金，大尺寸超细晶均质Cu-Cr合金的关键制备技术一直未获得突破。本申请从开发大尺寸均质超细晶CuCr合金制备新技术角度出发，提出了基于铝热还原-高频感应精炼制备大尺寸均质CuCr难混溶合金新思路。即，首先以氧化铜、氧化铬为原料，采用铝热自蔓延得互溶的CuCr高温熔体；然后高频磁场作用下精炼净化熔体；最后进行“水气复合冷却”快速凝固得到大尺寸均质铜铬合金铸锭。通过研究高频磁场强度、精炼坩埚材质以及复合冷却制度等对合金化学成分、微观精细结构（形貌、晶粒大小、组织分布）及致密度的影响规律，阐明铝热还原、高频电磁感应精炼、快速冷却过程中金渣界面反应和传递机制，以及第二相析出与粗化机制。开发出新一代具有我国自主知识产权的大尺寸均质超细晶铜铬合金触头材料制备关键技术。

CuCr合金因具有开断能力大、耐电压能力强、抗熔焊能力好、截流水平低等优点，已成为大功率真空开关触头材料的首选。但作为一种典型的难混溶合金，大尺寸均质Cu-Cr合金制备一直是制约性能提升和推广应用的关键。项目从冶金还原熔炼原位合成均质超细晶合金铸锭的角度出发，提出了以氧化铜、氧化铬为原料，铝热还原-感应精炼-水汽复合冷制备大尺寸均质CuCr合金的新思路。围绕新方法涉及的关键科学问题，项目首次采用高温共聚焦显微镜原位分析Cu-Cr合金的熔化与凝固过程中Cr相的微观形貌演变规律，提出了均匀温场中合适冷却强度快速凝固是制备大尺寸均质合金铸锭关键的新理念；通过对冷却强度和温度场对合金熔体凝固效果影响规律的研究，率先发明了铝热还原-高频感应精炼-水气复合冷却的新技术；首次提出反应物Cr2O3还原与造渣协同配料高效熔炼的冶金热力学与动力学设计新理念，解决了铝热快速还原原位合成CuCr合金过程中金渣分离不彻底以及合金铸锭致密度低的关键科学难题。成功制备出大致密均匀的大尺寸CuCr25-CuCr50合金铸锭，其密度由现有的粉末冶金法的8.00~8.17g/cm3提高到8.25~8.39g/cm3；完成了12KVA规格的真空灭弧室铜铬合金触头材料的耐压特性、截断电流和抗熔焊性等电性能第三方评价，均满足国标要求，尤其是耐压特性比国标要求指标提升近2倍，截断电流指标远优于国际最先进水平。项目成果形成了具有我国独立知识产权的铝热还原-高频感应精炼-水汽复合冷制备大尺寸均质CuCr难混溶合金第四代制备新方法、新技术，研制出其核心装备原型，实现了大尺寸均质铜基难混溶合金的低成本高效制备，为我国高性能铜基难混溶合金制备提供了理论基础和技术支撑。项目执行期间，发表论文 21 篇，其中SCI论文14篇；出版国家重点图书专著2部，获授权发明专利 6项；培养7名研究生（包括：毕业硕士研究生4名、毕业博士研究生1名，在读博士生2名）。