稀土精炼紫杂铜组织和性能的研究

Microstructure and Properties of Impure Red-Coppers Refined by Rare Earths

采用自制的稀土中间合金,利用直读光谱仪、金相显微镜(OM)、扫描电镜(SEM)和电化学工作站,研究了稀土La,Ce对紫杂铜精炼前后的化学成分、微观组织、力学性能和耐蚀性能的影响,并探讨了稀土除杂的热力学机制与稀土精炼提高耐腐蚀性能的机制。实验结果表明,稀土La,Ce精炼后,紫杂铜中的Pb,Sn,S含量明显降低,Bi,Al等杂质含量也有不同程度的降低;加入0.15%稀土La,Ce精炼后,紫杂铜的铸态组织明显细化;稀土La,Ce与铜基体形成了球状的Cu6RE第二相粒子,弥散分布于铜基体中;适量稀土La精炼后,紫杂铜的力学性能有较大改善;加0.10%La和0.15%Ce精炼后的紫杂铜在3.5%的Na Cl溶液中的耐蚀性能有较大改善,自腐蚀电流由精炼前的8.58μA·cm^(-2)分别下降到4.59和6.20μA·cm^(-2)。

Self-prepared Cu-RE master alloys were designed, fabricated and used as refining agents to refine impure red-coppers. The effects of rare earth （RE） elements La and Ce on chemical compositions, microstructures, mechanical properties and corrosion resistance were investigated by employing direct-reading spectrometer, optical microscope （OM）, scanning electron microscopy （SEM） and electrochemical workstation. The thermodynamic mechanisms of impurities removed by REs and the mechanisms of the improvement of corrosion resistance after rare earth refining were discussed. The results showed that the contents of impurities, Pb, Sn and S, decreased remarkably and the contents of other impurities, Bi and Al, also decreased to a certain extent after adding proper amounts of Cu-RE refining agents. The cast microstructures were refined obviously when 0.15% La and Ce were added. Rare earth elements, La and Ce, could form spherical second phase particles （ C% RE） with copper, and these particles distributed sporadically in copper ma- trix. The mechanical properties of impure red-coppers refined by rare earth element La improved greatly. The corrosion current density in 3.5% NaCl solution decreased from 8.58 μA cm-2 to 4.59 μA cm-2 and 6.20 μA cm-2 when the impure red-coppers were refined by 0.10% La and 0.15% Ce, and the corrosion resistance also improved after adding proper amounts of Cu-RE refining agents into impure red-coppers.