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Cu-Cr composites were prepared by self-made directional solidification equipment with the high temperature gradient and double-zone heating. The microstructural evolution was investigated during the directional solidification with the different solidification rate for Cu-1.0%Cr, Cu-1.7%Cr and Cu-5.6%Cr alloys, respectively. It is shown that for the hypoeutectic Cu-1.0%Cr alloy, the general microstructures consist of primary α(Cu) phase and the rod-like or needle-like (α β) eutectics, and for the hypereutectic Cu-1. 7%Cr and Cu-5.6%Cr alloys, α(Cu)phase, primary β(Cr) phase and (α β) eutectics coexist. With the increase of the solidification rate, the morphology evolution of every phase is that, 1st cellular(dendrite) of α(Cu) phase thins and cellular(dendrite) spacing shortens gradually, (α β) eutectics set in α(Cu) cellular or dendrite, and primary β(Cr) phase distributes unevenly on α (Cu) matrix, whose morphology undergoes the change from dendrite to particle. 相似文献
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快速凝固高强高导Cu-Cr合金的性能 总被引:11,自引:0,他引:11
采用单辊旋铸快速凝固技术制备了Cu-0.6~5.0Cr(原子分数,%)合金条带,对铸态及时效处理后的合金性能(包括电特性和显微硬度)进行了研究.结果表明快凝铸态合金经过适当的时效处理后,可以在保持较高的电导率的前提下,显著提高其硬度.还在Matthiessen假设的基础上,对快凝工艺和时效工艺对合金的电特性的影响进行了分析和讨论,依据合金强化机理对合金硬度进行了分析. 相似文献
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大功率真空开关铜铬触头材料 总被引:25,自引:4,他引:21
冼爱平 《中国有色金属学报》2001,11(5):731-740
综述了大功率真空开关铜铬触头材料最近的进展,主要内容包括:铜铬合金的发明及技术上的优点,铜络合金二元相图上的特点及常规铸造工艺上的困难。铜铬合金的主要制备工艺包括粉末烧结法,粉末烧结-熔渗法以及自耦电极法等,铜铬合金中杂质的影响,包括残余气体的影响,残余碳的影响及第二组元的影响等。对铜铬合金及其材料的显微组织对真空电触头的基本电性能(分析电流能力,抗电弧烧蚀能力,截断电流等)的影响进行了简要的概述,最后对铜铬合金进一步发展方向(如铬粒子细化,材料回收及准快速凝固工艺,喷射成型等)进行了简要的讨论。 相似文献
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In-situ observation of porosity formation during directional solidification of two Al-Si alloys (7%Si and 13%Si) was made by using of micro-focus X-ray imaging.In both alloys,small spherical pores initially form in the melt far away from the eutectic solid-liquid (S/L) interface and then grow and coagulate during solidification.Some pores can float and escape from the solidifying melt front at a relatively high velocity.At the end of solidification,the remaining pores maintain spherical morphology in the ne... 相似文献
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在0.6 MPa纯H2气氛中,采用金属/H2共晶定向凝固(Gasar)技术制备得到Gasar多孔Cu-x Cr合金。研究了Cr含量、凝固模式以及凝固速率对Gasar多孔合金气孔结构和显微组织的影响。结果表明,当合金以平面、胞状及柱状枝晶凝固时,Gasar多孔Cu-x Cr合金能获得定向生长气孔。当凝固方式转变为等轴枝晶凝固时,定向生长气孔发生中断。Gasar多孔Cu-x Cr合金(x=0.8%、1.3%)气孔在共晶相前沿析出,与共晶组织协同定向生长。随Cr含量增加,共晶组织体积百分比增加,孔隙率和孔圆整度进一步增加;随多孔Cu-1.3 Cr合金试样凝固高度增加,凝固速率下降,界面生长方式转变为等轴晶生长方式,则无法得到定向生长气孔。 相似文献
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采用中频感应熔炼炉制备了Cu-0.7Cr-0.15Zr和Cu-0.7Cr-0.15Zr-0.05Mg-0.02Si两种合金,研究了Mg、Si复合微合金化对Cu-Cr-Zr合金时效工艺参数、性能与析出动力学的影响。结果表明:Mg、Si复合微合金化提高了Cu-Cr-Zr合金的最佳时效温度,延长了保温时间,Cu-0.7Cr-0.15Zr合金的最佳时效工艺为410 ℃时效8h,Cu-0.7Cr-0.15Zr-0.05Mg-0.02Si合金的最佳时效工艺为430 ℃时效14 h。Mg、Si复合微合金化提高了Cu-Cr-Zr合金的强度与导电率,Cu-0.7Cr-0.15Zr合金最佳工艺条件下的强度为570 MPa、电导率为79.1%IACS;Cu-0.7Cr-0.15Zr-0.05Mg-0.02Si合金最佳时效工艺条件下的强度为595 MPa、电导率为80.4%IACS。Mg、Si复合微合金化改变了Cu-Cr-Zr合金Avrami相变动力学方程,减缓了时效析出过程。 相似文献
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热型连铸锌铝合金定向凝固线材的组织分析 总被引:4,自引:2,他引:4
对热型连铸锌铝合金定向凝固线材的铸态及热处理组织进行了观察、分析和讨论。结果表明:热型连铸锌铝合金线材的显微组织为定向生长的平行柱状枝晶组织;共晶合金ZA5的枝状芥是的每个枝晶都由多层片状共晶β和η两相构成,过共晶合金的组织为初生树枝晶和枝晶间共晶组织,其中ZA8,ZA12初生相为β相,ZA22和ZA27的初生相是α相。 相似文献
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1 INTRODUCTIONThephenomenonthattheinterfaceoftwospeci menscontactundertheeffectofmechanicloadisseeneverywhere[1] ,whilewhatistheact 相似文献
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AgCuZnSn合金具备高强度、成分无害化的优势,在绿色制造中应用前景广阔,但Sn元素的加入导致的成形性能下降,限制了其使用. 为克服该不足,设计了一种使用AgCuZn/ZnCuAgSn/AgCuZn复合焊片在钎焊过程中原位合成AgCuZnSn高强钎料的方法,采用的复合钎焊片外层为AgCuZn低熔合金,内层为ZnCuAgSn合金,二者熔点接近且内层合金低于合成后钎料熔点,复合钎料的加工性优于同成分的AgCuZnSn钎料. 使用复合钎焊片进行了感应钎焊不锈钢试验. 结果表明,钎焊过程中两种合金几乎同时熔化,经瞬间保温后可充分熔合,获得高强度钎缝,采用该工艺获得的接头强度高于常规钎焊连接强度. 相似文献
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对5种典型锌铝合金在热型连铸工艺条件下的连续定向凝固进行了研究, 探讨该工艺下锌铝合金线材表面缺陷的产生机理, 并对部分缺陷的组织结构进行了显微分析. 结果表明 只有金属液压头、型口温度、拉铸速度和冷却条件诸工艺参数在一定范围内的协调配合, 才能拉铸出表面光滑的锌铝合金线材. 不合理的工艺参数将导致热裂、表面粗糙、糊状型口和拉漏等缺陷. 固液两相区的形状和位置对上述缺陷的形成有重要影响, 当固液两相区位于型口或型内时, 凝固界面将向型内凸入, 如果剩余液体不能抵消凝固收缩, 就会出现表面粗糙; 若凝固界面深入型内较多, 则使型内凝固的铸锭摩擦力过大, 形成热裂; 固液两相区移至型外, 凝固界面将变成平面, 容易发生拉漏. 相似文献
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The purpose of this study is to predict the morphologies in the solidification process for Cu-0.6Cr (mass fraction, %) alloy by vacuum continuous casting (VCC) and verify its accuracy by the observed experimental results. In numerical simulation aspect, finite difference (FD) method and modified cellular automaton (MCA) model were used to simulate the macro-temperature field, micro-concentration field, nucleation and grain growth of Cu-0.6Cr alloy using real data from actual casting operations. From the observed casting experiment, the preliminary grain morphologies are the directional columnar grains by the VCC process. The solidification morphologies by MCAFD model are in agreement with the result of actual casting experiment well. 相似文献
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离心铸造Mg2Si和Si自生增强的锌基合金复合材料 总被引:2,自引:0,他引:2
采用热模金属型工艺,离心铸造白生增强的Zn-27Al-6.3Mg-3.7Si合金复合材料。研究结果表明;该合金内层聚集大量块状初生Mg2Si、少量块状初生Si,中层不含初生Mg2Si和初生Si,外层含少量初生Mg2Si和初生Si;Zn-27Al-6.3Mg-3.7Si合金在凝固过程中,先后经历了初生Si和初生Mg2Si的析出、富Al的固溶Zn相析出、Mg—Zn化合物的析出,以及发生三元或四元共晶反应;初生Mg2Si和初生Si的位置、数量和分布决定于其内浮速度和离心力场作用下的凝固速度;含有初生Mg2Si和初生Si的内层和外层比中层具有更高的硬度和耐磨性。 相似文献
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Fabrication of an in-situ nano-Al2O3/Cu composite with high strength and high electric conductivity 总被引:2,自引:0,他引:2
SHENYutian ZHUJing XUYanji WANGBaoheng LITongze 《稀有金属(英文版)》2005,24(1):46-54
A heat-resistant dispersion-strengthening nano-Al2O3/Cu composite with high strength and high electric conductivity was fabricated in a multiplex medium. The internal oxidation product, microstructures and properties of the composite,and the process flow were systematically studied. It is confirmed that this new technique simplifies the process and improves the properties of the composite. X-ray analysis indicates that the alumina particles formed during internal oxidation consist of a large mount of γ-Al2O3 and a certain amount of θ-Al2O3 and α-Al2O3. TEM observation shows that the obtained γ-Al2O3 nano-particles are uniformly distributed in the copper grains; their mean size and space between particles are 7 nm and 30 nm, respectively. The main properties of the composite with 50% cold deformation are as follows: the electric conductivity is 51 MS/m (87%IACS), σo= 628 MPa, and the hardness is HRB86. After annealing at 1273 K, all or most of the above properties remain, and the microstructures are still dependent on elongated fiber-form grains. 相似文献
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Solid lubricants lead to substantial weight savings relative to the use of liquid lubricant, especially in the weight-conscious aerospace industry. A new PTFE-Al alloy composite(A) containing 60% area proportion of PTFE composite was developed. Another type of common metal-plastics multilayer composite, also called DU, was selected for a comparative investigation. Friction and wear tests were carried out in an oscillating sliding tribotester in air at an oscillating frequency of 0.13 Hz and contact mean pressures from 10 to 80 MPa. The composites slid against a 38CrMoAlA steel shaft. The results show that the composite A exhibits low coefficient of dry sliding friction less than 0.1 and long wear life of 2 000 m. This is because the composite A can provide a sufficient solid lubrication during the whole tests. SEM examination of the transfer films for the composite A confirms that uniform, thin and coherent transfer films are prerequisites for low friction and good wear resistance. 相似文献