【作者】 朱达川；

【导师】 涂铭旌；

【作者基本信息】 四川大学 ， 材料学， 2001， 博士

【摘要】 在阅读了国内外大量文献的基础上，本文对铜及铜合金的发展史作了较为详尽的概述，特别是对高强高导铜合金的研究现状及其应用作了详细分析。针对现在所存在的缺点，在对高强高导铜合金应用领域的局限作了剖析的基础上，利用四川丰富的锂资源，研究开发出了新型高强高导的铜锂合金，利用锂优异的净化作用，锂的强化作用，同时利用其对纯铜电导率降低较小的特点，对其制备及使用过程中的相关作用效应进行了初步探讨，并以其强化作用、对导电性的影响为重点，探讨了其微观的强化机制和对电导率的影响机制。本研究达到了预期的研究目标，取得了以下具有理论价值和工程价值的创新性研究成果和新的研究进展： 1．优化了铜锂合金的制备工艺，探索出了一套安全可靠的制备工艺，简化了锂的添加工艺，制备了锂的分布均匀一致的铜锂系列合金，解决了前期研究中由于锂、铜密度相差较大而造成的分布不均的难点。 2．研究了锂的净化作用，研究发现：锂的加入，脱氧除硫效果极佳，但锂对工业纯铜中微量的铁、磷、硅等杂质基本上没有影响，这一点有别于前期报道中锂对纯铜中的铁、磷、硅等夹杂也有优异的净化作用的报道。 3．虽然前人认为锂的加入可细化纯铜晶粒，改善其机械性能，但本文对铜锂合金凝固特性的研究表明：1)微量锂的加入，粗化了纯铜晶粒，锂加入量为0.06w％时，铜锂合金晶粒尺寸为纯铜晶粒的1.7倍，高含量锂的加入，又使纯铜的晶粒细化，加入锂含量为2w％时，铜锂合金的晶粒尺寸仅为纯铜晶粒尺寸的1／2；2)锂加入铜液后，改变了铜锂合金的散热状况，减缓了合金凝固界面的温度梯度，消除了铜锂合金的柱状树枝晶区，全部 四川 大学博士学位论文转化为等轴晶，这种效应尚属首次报道。 4．对铜理合金在300℃、400℃、500t下的抗氧化特性及其在盐水中的耐蚀性的研究表明：1）锤的加入，改变了纯铜的氧化规律，具体表现为：在300’C以下时，不同含量的理，均不同程度地提高了工业纯铜的抗氧化性，在500’C，理使铜的抗氧化性有所下降，氧化速率有所上升，且理含量越高，氧化越严重；2）微量理加入到工业纯铜中，不降低纯铜的耐蚀性，甚而使耐蚀性稍有提高，而含Li量较高的Cu－Li合金耐蚀性较差。 5．通过理对工业纯铜在结晶温度的影响的研究结果表明：微量锤的加入，造成铜的晶格畸变，影响再结晶过程的位错运动与重排，减缓了晶界的迁移，从而抑制再结晶，将纯铜的再结晶温度由400t提高到440’C。 6．对纯铜及铜锤合金丝的力学性能的研究发现：二）微量袒加人工业纯铜中，造成铜的晶格畸变，其次由于理、铜原子的弹性模量不同，造成局部能量的变化，致使位错运动的阻力增大，另外，由于两者原子价态的差异，在局部区域产生极化，提高纯铜原子键强度，从而提高硬态铜丝的相关力学性能。2）由于理提高铜的再结晶温度，在常规铜热处理工艺下，铜锤合金丝再结晶程度较轻，其退火组织中仍保留有大量的形变组织，位错密度下降不大，其运动阻力仍然较纯铜退火组织的大，因此铜锤合金丝的抗拉强度下降较小，同时其延伸率较之纯铜，提高幅度也较小。 7．对纯铜及铜埋合金丝的电性能研究表明：l）理的加入，增大电子散射，同时影响了纯铜的价带，使纯铜费米面处的电子态密度下降，从而降低纯铜的导电率，但是由于理的良好的净化作用，两者相消后略微降低铜的导电率，随捏含量的增加，铜的导电率呈逐渐下降的趋势。2）锤对工业纯铜丝在硬、软态下的比电阻的影响系数分别为0．8422，0．9169，这是由于硬态下位错密度大，形变量大，从而增加电子散射所致。更多还原

【Abstract】 In this thesis, the development of copper and copper alloys, especially copper alloys with high strength and high conductivity, are reviewed in details. On the basis of thorough analysis to the applied limits of copper alloys according to the alloys’ defects, new Cu-Li alloys with high and high conductivity are manufactured and studied by means of rich lithium resource in Sichuan province. The relative effects of lithium to pure copper, such as purification , the effects to solidification characteristics , anti-corrosion and anti-oxidation properties , are discussed. Furthermore, the effects and the micro-mechanism of lithium to copper’s strength and conductivity are studied emphatically. The main creative results and new progress in this thesis are presented as follows:1. The manufacturing technology of Cu-Li alloys is optimized. It simplifies the process of adding lithium to molten copper. The Cu-Li series alloys that lithium is dispersed in copper uniformly have been developed. The process overcame the difficulty that lithium is not easy to be well dispersed because of great disparity in density between lithium and copper in earlier research.2. The purification effect of lithium to pure copper is studied. The result showed that the oxygen and sulfur contents decreased sharply when lithium is added to pure copper, but the iron, phosphors and silicon contents have little change. This is different from the earlier report that lithium also has purification effect to the iron, phosphors and silicon.3. Although the earlier researchers think that lithium can decrease copper grain size, different results are presented in this thesis. The study of lithium effect on solidification characteristics of copper shows as follows: 1) The copper grain size increases when trace lithium is added to copper liquid, the maximum grain size is 1.7 times of pure copper, but when lithium content is high, the grain size decreases, the minimum is only half of pure copper. 2) The dendrite crystal area of Cu-Li alloys is diminished after lithium is added to molten copper. It becomes equiaxed structure. So far, this kind of effect is reported firstly.4. The research result on the effect of lithium to anti-oxidation and anti-corrosion properties shows as follows: 1) Lithium added in copper changes the oxidation regularity. Different content of Lithium added in the pure copper can improve its anti-oxidation property at low temperature below 300 "C. But when the temperature is higher(500*C), the anti-oxidization decreased with the increase of lithium content. 2) Trace lithium added to pure copper can improve its anti-corrosion ability in NaCl saturated solution, but the ability decreases with the lithium’s content increasing.5. It has been showed that lithium added in pure copper improved its re-crystallization temperature from 400 *C to 440 "C. It is because trace lithium dissolved in copper make copper’s crystal lattice distort, hinder the movement and re-arrangement of dislocations, restrain the nucleating and grain boundary moving during re-crystallization process.6. The tensile strength and elongation percentage of pure copper was improved when trace lithium was added. This is because copper’s lattice deformity formed, leading to solid solution strengthening due to the addition of trace lithium. Secondary, the partial energy changes because of the difference of elastic coefficient between lithium and copper, so it increases the obstruction of dislocation. At the same time, the re-crystallization temperature of pure copper was improved due to the addition of lithium. The Cu-Li alloy samples still have much deformation organization at conventional heat-treatment system, so the strength decreased and elongation percentage increases slightly after annealing.7. Trace lithium added in copper liquid increased copper’s resistance slightly. The resistance increased gradually with the residual lithium content increasing. This is because lithium atom solutes in copper lattice, leading to copper’s crystal deformation.更多还原