【作者】 敖学文；

【导师】 程建奕；

【作者基本信息】 南昌大学 ， 材料学， 2010， 硕士

【摘要】 铜合金由于其优异的导热、导电性能和一定的强度,因而在国民工业中应用越来越广泛,而随着工业技术的发展,制备性能更优异的铜合金也成为了一个重要研究方向。对于高强度高电导性铜合金来说,时效强化型的Cu-Cr-Zr系合金具有其一些特有的优势而备受青睐,因而与之相关的制备方法、工艺也不断推陈出新。本文分别对三种不同成分Cu-Cr-Zr-Mg-Si合金时效特性进行了研究,分析了不同工艺参数和成分对合金组织与性能的影响,得出的主要结论如下：(1) Cu-Cr-Zr-Mg-Si合金在80%变形后480℃时效时可获得较好的综合性能,而在540℃时效30min后,合金发生过时效。升高温度和增大变形量加速合金的时效析出过程,随温度升高合金的导电性能有所提高；适当的加大变形量有助于提升合金的显微硬度,而对电导率影响不大。(2)在总变形量相同的情况下,通过二级变形时效工艺能提高Cu-Cr-Zr-Mg-Si合金的综合性能。显微硬度要比一级变形时效工艺提高6%-9%,电导率较之一级变形时效工艺也有所提高,可达88%IACS。(3)含量1.0%Cr的合金固溶后晶粒更细小,且时效后峰值硬度要高出0.6%Cr合金10-15HV,在不过时效时的整体硬度都要高于含量0.6%Cr的合金,而电导率要稍低于0,6%Cr合金。(4)Cu-0.6Cr-0.15Zr-0.05Mg-0.02Si添加了少量稀土Y后合金的组织得到改善,且对合金的硬度提升很大。且添加稀土Y推迟了硬度峰值出现的时间,并且使合金中的析出相更细小,析出相分布更弥散,硬度峰值可达174HV,而电导率稍有下降,但时效一小时之后均达到82%IACS以上。(5) Cu-Cr-Zr-Mg-Si合金经变形时效处理后在扫描电镜下可以看到在晶内有着球形和棒状的析出相颗粒,经能谱分析确定为Cr颗粒和Cr的碳化物。(6)TEM观察发现,二级变形时效工艺合金中的析出相很小,粒径为2nm左右,且分布均匀,如此细小的析出相粒子对位错运动有强烈的阻碍作用,同时会造成位错的增殖。(7)观察合金变形时效处理后的拉伸断口形貌,可以看出其是典型的韧窝断口形貌特征,且将断口形貌放大后并没有观察到夹杂物或者第二相粒子,说明这些析出粒子很细小且合金内部组织较好。更多还原

【Abstract】 Copper alloy has been widely applied in the national industry because of its excellent thermal conductivity, electrical conductivity and certain strength. With the development of industry technology, preparation of better performance of copper alloy has become an important research direction. For high strength and high conductivity copper alloy, the aging hardening type Cu-Cr-Zr alloys have its unique advantage and therefore the associated preparation technology has continued to emerge. This paper studied aging characteristics of Cu-Cr-Zr-Mg-Si alloy with three different compositions and analyzed the effect of process parameters and composition on microstructure and properties. The main conclusions were shown as follows:(1) Cu-Cr-Zr-Mg-Si alloy has a good comprehensive performance after 80% deformation and aging at 480℃. The alloy over-aged while aging at 540℃×30min. Increasing of temperature and deformation could accelerate the process of precipitation. Increasing of temperature could improve the electrical conductivity of the alloy and increase deformation could improve hardness, but deformation has not much effect on the final electrical conductivity.(2) Under the same deformation, two-step deforming and aging process can increase the Cu-Cr-Zr-Mg-Si alloy overall performance, the micro-hardness is 6%-9%higher than one-step deforming and aging process.The electrical conductivity also higher than one-step deforming and aging process, which can reach 88%IACS.(3) The alloy with 1.0%Cr has smaller grains after solid solution, and peak hardness after aging is 10-15HV higher than 0.6%Cr alloy. The overall hardness is higher and electrical conductivity is slightly lower when the alloy does not over aged.(4) Adding of trace amount of rare earth Y in Cu-0.6Cr-0.15Zr-0.05Mg-0.02Si can improve alloy microstructure and hardness. Also will postpone peak time of hardness and make the precipitates more small and dispersed distributed. The hardness can reach 174HV and electrical conductivity has a slightly decrease, but after one hour aging it could reach above 82%IACS.(5) The spherical and rodlike particles precipitates in Cu-Cr-Zr-Mg-Si alloy after deforming and aging treatment was observed by the scanning electron microscope. EDS identified as Cr carbide particles and Cr.(6) TEM showed that two-step deforming and aging process alloy has small precipitates, which are about 2nm and uniform distributed. Those small precipitates will strongly hinder the dislocation movement, and it will result in the multiplication of dislocations.(7) The fracture of as-aged alloys features with a typical toughness failure. The second phase particles were not observed in the fracture surface. It means that these precipitated particles are small.更多还原