稀土在紫铜及白铜合金中的作用规律及应用研究

【作者】 张振峰；

【导师】 林高用； 张胜华；

【作者基本信息】 中南大学 ， 材料加工工程， 2007， 硕士

【摘要】 本文结合江苏省科技成果转化项目“稀土铜合金材料及相关技术的研究与产业化”[BA2006034],以稀土在铜及铜合金中的工业应用为目的,围绕稀土在铜及铜合金中的作用与功效,从稀土对紫铜组织和力学性能的影响、铜.稀土中间合金的研制及其在杂铜中的应用、稀土对BFe10-1-1合金耐海水冲刷腐蚀性能的影响等三个方面开展了较系统的研究,获得如下主要结论:1.稀土元素对紫铜微观组织和力学性能影响的研究为稀土能更好地应用于紫铜的工业生产,从紫铜中不同的稀土加入量和稀土含量的角度研究了稀土对紫铜组织和力学性能的影响:（1）稀土能有效的净化紫铜熔体,去除杂质元素;少量杂质元素通过与稀土、铜反应形成弥散化合物粒子,对紫铜发挥有益作用;过量稀土在紫铜熔炼过程中造渣严重,降低熔体流动性;在紫铜中直接加入稀土,稀土吸收率低,烧损率大;（2）随着稀土含量的增加,紫铜晶粒先减小后增大;而紫铜的强度和硬度随着稀土含量的增加分别先升高后下降,当稀土含量为0.04%时,紫铜试样获得最好的综合力学性能,即退火态试样的抗拉强度达到251MPa,屈服强度为116MPa,延伸率达到37.22%;（3）随着稀土含量的增加,紫铜的再结晶温度升高。2.铜—稀土中间合金的研制及其对杂铜精炼作用的研究为减少稀土在熔炼中的烧损、简化熔铸工艺,采用非真空熔炼法,配制了三种铜—稀土二元中间合金精炼剂,并利用其精炼了两种杂铜,通过各种检测手段,研究了中间合金精炼剂对紫杂铜和杂白铜的精炼效果与变质作用:（1）按照Cu-15%RE的中间合金成分,配制了三种不同的Cu-RE中间合金:Cu-14.6%La、Cu-6.8%Ce-4.2%La和Cu-9.6%Ce-2.0%La;其中Cu-14.6%La中间合金为共晶组织,Cu-6.8%Ce-4.2%La和Cu-9.6%Ce-2.0%La中间合金形为亚共晶组织,并且Cu-RE中间合金中主要有以下相的存在:Cu、LaCu₆、CeCu₆、Cu₄La、Cu₁₃La;（2）Cu-14.6%La中间合金精炼剂对紫杂铜和杂白铜的精炼效果和变质效果最好,其次是Cu-9.6%Ce-2.0%La和Cu-6.8%Ce-4.2%La中间合金精炼剂;实验结果表明Cu-RE精炼剂能有效除去紫杂铜和杂白铜中的杂质元素,如O、S、P、Bi、Pb、Fe、Al等,净化熔体,并且Cu-RE精炼剂能细化晶粒、净化晶界、改善组织;（3）相比于直接加入稀土的方法,采用加入Cu-RE中间合金的方式能大大降低稀土的烧损率、简化熔炼工艺,并且能有效的控制稀土的加入量,有利于工业应用。3.稀土元素对BFe10-1-1合金耐海水冲刷腐蚀性能影响的研究在实验室内利用人造海水模拟真实的海水冲刷腐蚀环境,进行了不同稀土含量的BFe10-1-1合金耐海水冲刷腐蚀的对比实验,对不同稀土含量BFe10-1-1合金在海水中的腐蚀规律进行了研究:（1）对于相同稀土含量的BFe10-1-1合金,海水流速越大,合金腐蚀速率越大;对于相同的海水流速,含稀土元素0.04%的Cu-Ni-Fe合金耐海水冲刷腐蚀性能最好,含过量稀土元素（0.19%）的Cu-Ni-Fe合金耐海水冲刷性能最差;（2）当BFe10-1-1合金内含有适量稀土元素时,Cu-Ni-Fe合金合金的耐海水冲刷腐蚀性能最好,合金表面形成一层致密的含稀土相的腐蚀产物层（如CeNi₅）,且不易脱落,能有效的减缓腐蚀速率,提高耐海水冲刷腐蚀性。更多还原

【Abstract】 This research is supported by achievement transformation items of Jiangsu province for science and technology-"Research and Industrialization of RE-Cu Alloys and Interrelated Technologies" [BA2006034]. For the purpose of broadening applications of RE elements on the industrial fabrication of copper and copper alloys, a series basic research on some applied sections of RE on copper and copper alloys industry is carried out. The primary investigations of this paper include three main parts: effects of RE elements on microstructures and mechanical properties of pure copper, the development of Cu-RE interalloys and its’ application on scrap copper, influences of RE elements on flushing corrosion-resistance of marine water for BFe10-1-1 alloy. The main conclusions are as follows:1. Study on the effects of RE elements on microstructures and mechanical properties of pure copperThe effects of RE elements on microstructures and mechanical properties of pure copper are investigated from the point of view of addition and content of RE:（1） RE effectively purifies the molten copper and deprives harmful elements from pure copper. But the absorptivity of RE in copper is very low when just adding RE to molten bath directly.（2） The proper RE additions can refine the microstructure and optimize the mechanical properties of pure copper. Over-added RE declined to form a mass of RE-rich phases deteriorating the mechanical properties.（3） The recrystallization temperature of pure copper rises with increasing of RE content.2. The development of Cu-RE interalloys and its’ application on scrap copperFor the sake of reducing the burning loss of RE and simplifying the casting craft, three kinds of Cu-RE binary interalloy refiners were fabricated. Scrap coppers were refined respectively by Cu-RE refiners. The refinement of Cu-RE refiners on scrap coppers was investigated using various research methods:（1） Three kinds of Cu-RE binary interalloys were fabricated according to eutectic composition Cu-15%RE: Cu-14.6%La, Cu-6.8%Ce-4.2%La and Cu-9.6%Ce-2.0%La. Thereinto, Cu-RE interalloy Cu-14.6%La is eutectic structure; both Cu-6.8%Ce-4.2%La and Cu-9.6%Ce-2.0%La are hypoeutectic structure. The majority phases in Cu-RE interalloys are: Cu、LaCu₆、CeOi₆、Ca₄La₆ Cu₁₃La;（2） Contrasting to other two refiners, the refinement of Cu-RE refiner Cu-14.6%La is the best. Refiners deprive harmful elements from matrix effectively such as: O、S、P、Bi、Pb、Fe、Al, and purify the molten bath. In addition, Cu-RE refiner can refine grains, purify grain boundaries and improve the structures;（3） Comparing to adding RE directly, adding Cu-RE interalloy to molten bath can reduce burning loss of RE greatly, simplify the casting craft and accurately control the content of RE.3. Study on the influences of RE elements on flushing corrosion-resistance of BFe10-1-1 alloys in marine waterThe real environments of marine water flushing corrosion were simulated in laboratory and the contrast tests of marine water flushing corrosion about BFe10-1-1 alloys with different RE content were carried out also. The results are following:（1） For the same chemical compositions, the faster the water flows, the higher the corrosion velocity of BFe10-1-1 alloy is. Fixing the velocity of flow, BFe10-1-1 alloy has the best flushing corrosion-resistance of marine water when the RE content is 0.014wt%.（2） When BFe10-1-1 alloy has proper RE elements, its corrosive surface form a layer of compact corrosive products which contant RE phases such as CeNi₅. The corrosive products combine with each other firmly and difficult to fall off from surface under the flushing of marine water.更多还原