共查询到18条相似文献,搜索用时 91 毫秒
1.
为了研究塑性变形对单晶铜线材导电性的影响,以及电阻率与塑性变形量之间的定量关系,将Φ8mm的工业单晶铜线材冷拔后,得到塑性变形量不同的试样,用四端引线法精确测量其电阻率、结果表明,单晶铜线材的电阻率随塑性变形量的增加而上升,其原因是由于单晶铜线材的微观组织畸变程度随塑性变形量的增加而加剧。 相似文献
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本文对单股铜导线一次短路熔痕过渡区处的晶粒及气孔显微特征进行观察,并利用Image-Pro Plus软件对所得金相图像进行处理分析,并与国家标准(《电气火灾原因技术鉴定方法》GB/16840.1-1997)作比较,从而得出线径、温度对铜导线一次短路熔痕过渡区处晶粒粒径,气孔面积的影响规律。 相似文献
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基于晶体滑移理论和率相关的晶体滑移有限元程序, 对压缩面力作用下的各向异性铜双晶晶界平面处应力场进行了计算, 对晶界附近应力变化与晶粒滑移变形进行了分析;根据梁变形理论, 对垂直晶界的周期性扭曲变形和周期法向应力进行了理论分析和推导说明.结果表明:在晶界处存在较大的应力梯度和应力集中现象, 晶粒的取向对晶界面的应力分布有很大的影响, 晶粒的滑移变形是从部分区域先行开动. 相似文献
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初始直径为Φ8 mm的纯铜杆坯经拉拔得到直径为Φ1.8 mm和Φ0.171 mm的铜导线.采用光学金相显微镜、微机控制电子万能实验机和直流低电阻测试仪研究了拉拔过程中纯铜导线微观组织、力学性能和电阻率的变化.结果表明,在拉拔过程中导线微观组织沿拉拔方向逐渐形成纤维组织.抗拉强度和电阻率随着变形程度的增加而增大,直径为Φ8 mm的纯铜杆坯经过单道次拉拔后得到直径为Φ1.8 mm的纯铜导线,抗拉强度由226 MPa增至380 MPa,断后延伸率由45%下降至35%,电阻率由0.0169Ω?mm2?m-1增至0.0172Ω?mm2?m-1.由拉拔过程中的微观组织变化情况得到了微观组织和力学性能之间的关系,即随着纤维状组织的形成,纯铜导线的抗拉强度增加,断后延伸率降低. 相似文献
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李晓桓 《昆明冶金高等专科学校学报》1997,(3)
对一般无定向导线、闭合无定向导线及附合导线的精度进行了讨论及分析比较,得出闭会无定向导线的精度比一般无定向导线的精度高2倍左右,附合导线比闭合无定向导线的精度高3倍.同时得出,闭合EDM无定向导线是一种很有潜力及值得推荐使用的导线. 相似文献
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紫杂铜中杂质行为的研究 总被引:2,自引:0,他引:2
采用喷射冶金技术,讨论了紫杂铜中杂质总量对铜延伸率和电阻率的影响规律,分析了工艺因素对杂质去除的影响,给出了铜液中杂质去除的速度,确定了铜液中杂质去除的工艺要点,使电工用铜T2黑杆超过了GB3952-83IEC28标准。 相似文献
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分别选用过硫酸铵、双氧水、三氯化铁作为掺杂剂,对聚苯硫醚(PPS)纤维进行液相掺杂,并对掺杂后PPS纤维的结构和性能进行表征,探索其导电机理,研究其导电性.结果表明,过硫酸铵作为掺杂剂时效果最好,可使其电导率从10-13S/cm升高到10-7S/cm. 相似文献
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采用第一性原理赝势平面波方法计算了立方萤石型CeO2的晶体参数.在此基础上,计算了能带结构、总态密度、分波态密度和布居分布,分析了CeO2的的电子结构,研究了其导电性较弱的原因. 相似文献
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The deformation microstructure evolution of single crystal copper wires produced by OCC method has been studied with the help
of TEM, EBSD and OM. The results show that there are a small number of dendrites and twins in the undeformed single crystal
copper wires. However, it is difficult to observe these dendrites in deformed single crystal copper wires. The structure evolution
of deformed single crystal copper wires during drawing process can be divided into three stages. When the true strain is lower
than 0.94, macroscopic subdivision of grains is not evident, and the microscopic evolution of deformed structure is that the
cells are formed and elongated in drawn direction. When the true strain is between 0.94 and 1.96, macroscopic subdivision
of grains takes place, and the number of microbands located on {111} and cell blocks is much more than that with the true
strain lower than 0.94. When the true strain is larger than 1.96, the macroscopic subdivision of grains becomes more evident
than that with the true strain between 0.94 and 1.96, and S-bands structure and lamellar boundaries will be formed. From EBSD
analysis, it is found that part of 〈100〉 texture resulting from solidifying is transformed into 〈111〉 and 〈112〉 due to shear
deformation, but 〈100〉 texture component is still kept in majority. When the true strain is 0.94, the misorientation angle
of dislocation boundaries resulting from deformation is lower than 14°. However, when the true strain arrives at 1.96, the
misorientation angle of some boundaries will be greater than 50°, and the peak of misorientation angle distribution produced
by texture evolution is located in the range between 25° and 30°.
Supported by the National Natural Science Foundation of China (Grant Nos. 50471098 and 59971033), the Natural Science Foundation
of Shaanxi Province, China (Grant No. 2003E101), and the Teaching and Research Award Program for Outstanding Young Teachers
in Higher Education Institution of MOE, China 相似文献
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晶粒度对多晶铜纳米压痕表面变形机理影响 总被引:1,自引:0,他引:1
为研究晶粒度在多晶材料纳米压痕过程中对其塑性变形机制及位错演生过程影响.采用Poisson-Voronoi和Monte Carlo方法建立大规模多晶铜分子动力学模型,针对多晶铜Hall-Petch效应曲线建立具有不同晶粒度的多晶铜模型,并与单晶铜纳米压痕模型对比,采用分子动力学方法模拟计算金刚石探针压入模型的纳米压痕过程,计算4种模型的缺陷结构的配位数、内应力、原子势能等参数.采用中心对称参数法研究压痕过程中位错等缺陷结构的演化机制.结果表明:具有不同晶粒度的多晶铜纳米压痕过程存在显著的规律性,单晶铜压痕力高于多晶铜,多晶铜压痕力随着晶粒度降低而下降;多晶铜的晶界结构能够限制压痕缺陷、内应力与原子势能向材料内部传递,而单晶铜难以限制此传递过程;压痕过程中,具有较小晶粒度的多晶铜具有更高的静水压力、范式等效应力与原子势能,单晶铜内应力与原子势能低于多晶铜.表层及亚表层为较低晶粒度而材料内部为较大晶粒度的梯度晶粒度材料具有极大的研究价值. 相似文献
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为了研究挤压温度对高纯铜微观组织和变形行为的影响规律,通过反向挤压方式对高纯铜进行不同挤压温度下的挤压实验并观察了其显微组织.结果表明,随着挤压温度的升高,高纯铜的晶粒尺寸增大.当挤压温度为650 ℃时,挤压棒材的平均晶粒尺寸为36 μm;当挤压温度升至800 ℃时,挤压棒材的平均晶粒尺寸为51 μm.随着变形量的增加,当挤压温度为650~700 ℃时,压余变形区的平均晶粒尺寸趋向于由60 μm变为45 μm;当挤压温度为750~800 ℃时,平均晶粒尺寸则趋向于由90 μm变为75 μm.800 ℃挤压变形后晶粒内部出现大量以Σ 3特殊晶界为孪晶界的<111>60°退火孪晶. 相似文献
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ZA27合金中Y及Fe的晶界偏聚电子理论研究 总被引:2,自引:0,他引:2
根据分子动力学理论建立了液态ZA27合金的原子集团,结合计算机编程构造出ZA27合金α相与液相共存时的原子构形及α相大角度重位点阵晶界模型.利用递归法计算了Fe、Y固溶于晶粒内,游离于固液相界面及其在α相晶界处的环境敏感镶嵌能.由此得出:Fe、Y处于固液相界区时比在晶内更稳定,并解释了Fe、Y在α相内溶解度很小,结晶时富集于固液相界前沿液体中,从而导致凝固结束后Fe、Y偏聚于晶界,形成成分复杂的稀土化合物的事实. 相似文献
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Submicron diamonds were co-deposited on aluminum substrates with copper from the acid copper sulfate electrolyte by electrolyte-suspension co-deposition.After submicron diamonds were added to the electrolyte,the shape of copper grains transformed from oval or round to polyhedron,the growth mode of copper grains transformed from columnar growth to gradual change in size,and the preferred orientation of copper grains transformed from (220) to (200).Analyzing the variation of cathodic overpotential,it was found that the cathodic overpotential tended to remain unchanged when copper plane (220) grew in the process of electrodepositing pure copper,while it tended to decrease with time when copper plane (200) grew m the process of co-deposition.It was inferred that copper plane (200) was propitious to the deposition of submicron diamonds. 相似文献
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We report recent advances in the experimental and theoretical study of grain size(GS)effects on the thermal and mechanical properties of nanostructured NiTi polycrystalline shape memory alloy(SMA).It is shown that when GS<60 nm,the superelastic stress-strain hysteresis loop area(H)of the polycrystal decreases rapidly with GS and tends to vanish as GS approaches 10 nanometers.At the same time,the temperature dependence of the transition stress also decreases with GS and eventually approaches zero,leading to a wide superelastic temperature window and breakdown of the Clausius-Claperyon relationship.Rate dependence of the stress-strain responses is significantly reduced and the cyclic stability of the material is improved by the nanocrystallization.It is proposed that the emergence of such significant changes in the behavior of the material with GS reduction originate from the large increase in the area-to-volume ratios of the nanometer-thick interfaces(grain boundary and Austenite-Martensite(A-M)interface)in the polycrystal.In particular,with GS reduction,interfacial energy terms will gradually become dominant over the bulk energy of the crystallite,eventually bring fundamental changes in the phase transition responses of the material.Modelling strategy leading to the establishment of quantitative relationships among GS,grain boundary,A-M interfaces and the macroscopic responses of the material are outlined. 相似文献
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Preparation of copper nano-wires by template synthesis method 总被引:1,自引:1,他引:0
Highly ordered and porous anodic aluminum oxide templates were prepared. The ordered copper nanowires arrays were assembled in nano-holes of the template by alternating current electrodeposition at lower voltage.The morphologies of template and copper nano-wires arrays were characterized by means of field emission scanning electron microscope(FESEM) and the crystal structure of copper nano-wires was determined by means of X-ray diffraction. The results indicate that copper nano-wires hold the preferred crystalline orientation along (111), (200),(220) and (331) crystal faces during growth, and the growth of copper nano-wires in the nano-holes of the template is homogenous and continuous. 相似文献
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宋申华 《武汉理工大学学报(材料科学英文版)》2007,22(1):1-6
The combined effect of phosphorus grain boundary segregation and hardness on the ductile-to-brittle transition was examined for a P-doped 2.25CrlMo steel by using Auger electron spectroscopy in conjunction with hardness measurements, Charpy impact tests and scanning electron microscopy. With prolonging time at 540 ~C after water quenching from 980℃, the segregation of phosphorus increases and the hardness decreases. The DBTT (FATT) increases with increasing phosphorus segregation and decreases with decreasing hardness. The effect of phosphorus segregation is dominant until 100 h aging and after that the hardness effect becomes dominant. This effect makes the DBTT (FATT) decrease with further prolonging ageing time although the segregation of phosphorus still increases strongly. 相似文献