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紫杂铜中多种微量杂质元素并存,其中的杂质元素会恶化铜材的加工性能和物理力学性能,进而缩短铜材的使用寿命。稀土元素在紫杂铜中可以起到除杂、微合金化、细化组织、改善力学性能和耐蚀性能等多种作用。分别从稀土元素镧、铈在铜中除杂的热力学原理、除杂顺序、稀土相的存在形式、微合金化机制、稀土诱导铜微观组织转变的判据及工业化应用等方面进行了研究和阐述。结果表明,稀土的净化作用、晶粒细化及第二相强化作用可以改善紫杂铜的力学性能和耐蚀性能,稀土Ce除杂的热力学顺序为:O>S>Bi>Sn>Pb>Si>Al>Ag>Fe。稀土微合金化可以使铜的凝固组织发生柱状晶向等轴晶的转变(CET),稀土的净化效应和成分过冷共同作用导致了纯铜中CET的转变,建立了基于稀土含量为判据的CET预测模型,并确定了铜凝固组织发生CET转变的临界稀土La含量为0.14%。未来,紫杂铜的稀土除杂直接再利用技术有望得到实际工业应用。
Purple copper in a variety of trace impurities coexist, in which the impurities will deteriorate copper processing performance and physical and mechanical properties, thereby shortening the service life of copper. Rare earth elements in purplish copper can play a variety of roles such as impurity removal, micro-alloying, refine the organization, improve the mechanical properties and corrosion resistance. The thermodynamic principles of rare earth element lanthanum, cerium removal in copper, the order of impurity removal, the existence of rare earth phases, the mechanism of microalloying, the criterion of rare earth-induced transformation of copper microstructure and its industrial application were studied and elaborated . The results show that the rare earths purification, grain refinement and second phase strengthening can improve the mechanical properties and corrosion resistance of rare earth copper. The thermodynamic order of rare earth Ce removal is: O> S> Bi> Sn> Pb> Si> Al> Ag> Fe. Rare earth micro-alloying can make the solidification of copper columnar crystal to the equiaxed crystal transformation (CET), rare earth purification effect and undercooled components lead to the transformation of CET in pure copper, established based on the rare earth content as a criterion The CET prediction model was established and the critical rare earth element La content of CET transition was 0.14%. In the future, the rare earth impurity removal technology of purple miscellaneous copper is expected to get practical industrial application.