The formation of supersaturated solid solutions in Fe-Cu alloys deformed by high-pressure torsion

Fully dense bulk nanocomposites have been obtained by a novel two-step severe plastic deformation process in the immiscible Fe-Cu system. Elemental micrometer-sized Cu and Fe powders were first mixed in different compositions and subsequently high-pressure-torsion-consolidated and deformed in a two-step deformation process. Scanning electron microscopy, X-ray diffraction and atom probe investigations were performed to study the evolving far-from-equilibrium nanostructures which were observed at all compositions. For lower and higher Cu contents complete solid solutions of Cu in Fe and Fe in Cu, respectively, are obtained. In the near 50% regime a solid solution face-centred cubic and solid solution body-centred cubic nanograined composite has been formed. After an annealing treatment, these solid solutions decompose and form two-phase nanostructured Fe-Cu composites with a high hardness and an enhanced thermal stability. The grain size of the composites retained nanocrystalline up to high annealing temperatures.     

机械合金化形成的Fe—Cu纳米晶过饱和固溶体的硬化及软化

用机械合金化方法，在不互溶的Ｆｅ－Ｃｕ二元系的富Ｆｅ端和富Ｆｅ端和Ｃｕ端，分别制备出ｂｃｃ和ｆｃｃ结构的纳米晶过饱和固溶体，用Ｘ射线衍射和显微硬度分析等方法，系统研究了晶粒尺寸，溶质原子含量等因素对Ｆｅ－Ｃｕ纳米晶过饱和固溶体硬度的影响。结果表明，在富Ｃｕ端形成的ｆｃｃ纳米晶过饱和固溶体的硬度、随溶质原子Ｆｅ含量的增加而升高，而在富Ｆｅ端形成的ｂｃｃ纳米晶过饱和固溶体的硬度，随溶质原子Ｃｕ量的增加     

热压烧结Fe3Si-Cu在NaOH溶液中的腐蚀行为

以原子比为3∶1的Fe粉和Si粉球磨20 h后与一定量的Cu粉混合,在(1000±30)℃,20 MPa的压力下热压烧结制备了致密的Fe3Si-Cu复合材料。通过浸泡腐蚀和电化学腐蚀两种方法研究加入不同质量分数Cu(5%,10%)的Fe3Si-Cu复合材料在0.6、0.7和0.8 mol/l的NaOH溶液中的腐蚀行为。结果表明,两种材料在不同摩尔浓度的NaOH溶液中的腐蚀是一种均匀的全面腐蚀。复合材料中的Fe3Si和Cu两相在NaOH溶液中组成一腐蚀电池,其中Fe3Si为阳极发生腐蚀,Cu作为阴极得到保护;Fe3 Si-5%Cu复合材料在NaOH溶液中的自腐蚀电位随NaOH浓度的增加而增加,自腐蚀电流在0.7 mol/l的NaOH溶液中最低;Fe3 Si-10%Cu在三种浓度的NaOH溶液中的自腐蚀电位相差较小,自腐蚀电流在浓度为0.6 mol/l的NaOH溶液中最小,在0.7mol/l的NaOH溶液中最大。     

少量硼对Fe—Cu纳米粉粒固溶度的影响

用化学还原法制备了Ｆｅ－Ｃｕ过饱和固溶合金粉。Ｆｅ－Ｃｕ纳米粉中含有少量硼可扩展ｆｃｃ相的成分范围。合金粉体中Ｆｅ和Ｃｕ的原子比达到４：１时，主相仍保持ｆｃｃ结构，ｆｃｃ相区的范围可超过采用机械合金化法制备的Ｆｅ－Ｃｕ合金。对样品的退火处理研究证明了Ｆｅ－Ｃｕ系过饱和固溶合金的ｆｃｃ相相当稳定。     

~(199)Sn AND ~(57)Fe MOSSBAUER SPECTROSCOPIC STUDY OF THE MECHANICALLY ALLOYED Fe-Sn ALLOYS

1.IntroductionMechanicalalloyinghasbeenwelldevelopedasapowerfultechniqueofsolidstatere-artiontosynthesizealloysfarfromequilibrium,suchasamorphous,quasicrystajlineandnanocrystajlinealloys,etc.II--3].InFe-Snsystem,alltheiron-stannidesareferromagneticatroomtemperatureI4],thereforetheevolutionofmechanicalalloyinganddetailedchemicaldrirmationcanbeobtainedfromboththe57Feand119SnMossbauerspectraandcorre-spondinghyperfineparameters.The57Feand119SnMossbauerstudyofFe3Snpowdersbailaflledfor400hshowe…     

亚稳态Fe-Cu固溶体合金的(Ms-电子/原子)曲线

用机械合金化(MA)锻压方法制备了bcc和fee结构的块状亚稳态Fe-Cu固溶体系统,并对系统的磁化强度、价电子结构进行了测量和计算,从亚稳态Fe-Cu固溶体的饱和磁化强度Ms-e／a(电子／原子)曲线可看出：大约在26．2e／a的区域Ms有最大值,并且在大约28．6e／a的区域接近零．这个结果与Fe-Co和Fe-Ni系统类似(在大约26．2e／a的区域Ms最大,在大约28．6e／a时Ms近似为零).由此我们推论：相对在0K亚稳态Fe-Cu固溶体的每原子的电子数字的饱和磁矩(Ms)曲线与其它二元过渡金属(Fe-Co和Fe-Ni)的曲线类似．在Cu含量大约为35mol％(此时平均电子结构为27．1e／a)时的混合相区域出现负的曲率．     

银铜镍钎料钎焊高氮不锈钢的分子动力学模拟

利用Lammps软件对AgCuNi钎料真空钎焊高氮不锈钢的相关二元体系（Fe-Cu和Fe-Ni）元素扩散过程进行分子动力学模拟。结果表明,Fe-Cu和Fe-Ni二元体系相互扩散现象明显,扩散层厚度随着扩散时间增加而增加。在Fe-Cu体系的扩散过程中只有原子相互扩散,但Fe-Ni体系的扩散过程中既有原子扩散又有中间相生成。在Fe-Cu二元体系中,Fe原子的均方位移和扩散系数均大于Cu原子,因此Fe原子的扩散能力大于Cu原子。在Fe-Ni二元体系中,Fe原子的均方位移和扩散系数都大于Ni原子,因此Fe原子的扩散能力也大于Ni原子。随着扩散温度升高,原子均方位移和扩散系数增大,扩散能力越强。     

金属间化物Nd(Fe_(1-x)Co_x)_(10)V_2的磁性能机制

通过X射线衍射.磁测量和M(?)ssbauer谱测定了Nd（Fe1-Cox）10V2的结构和磁性.结果表明,Nd（Fe1-xCox）10V2（x=0,0.05,0.10,0.15,0.20）化合物的晶体结构均为ThMn12型结构;随着 Co含量x的增大,晶格常数将单调减少.Co原子的替代将导致化合物各个Fe晶位上的磁超精细场值Bhf逐渐增加.Co部分取代Nd（Fe1-xCox）10V2中的Fe原子时.将择优占据8i铁晶位.取向样品NdFe10V2的热磁曲线和变温M(?)ssbauer谱研究结果表明.该化合物在T=120K条件下存在自旋重取向现象.     

The effect of copper(II) on the formation of γ-FeOOH

Various γ-FeOOH samples have been synthesized by air oxidation of FeSO₄ solution with or without addition of Cu(II) (0–46 at.%Cu/Fe) and examined by X-ray diffraction, electron-microscopic observation, BET surface area determination, infra red absorption, DTA and chemical analyses. A destructive action of doped Cu(II) ions on the crystal formation was apparently recognized and discussed based on the crystallographic structure. The possible mechanism of crystallization of γ-FeOOH appears to differ between pure and Cu-doped γ-FeOOH, particularly one containing nearly 50%Cu.     

高能球磨制备Al-Pb-Si-Sn-Cu纳米晶粉末的特性

通过机械合金化制备了Al-15％Pb-4％Si-1％Sn-1．5％Cu(质量分数)纳米晶粉末。采用X射线衍射(XRD)，扫描电镜(SEM)和透射电镜(TEM)对不同球磨时间的混合粉末的组织结构、晶粒大小、微观形貌以及颗粒中化学成分分布情况进行了研究。结果表明混合粉末经过球磨后形成了纳米晶，其组织非常均匀。球磨对Pb的作用效果明显大于对Al的作用效果，经过40h球磨后Pb粒子达到40nm，而Al在球磨60h后晶粒为65nm；经球磨后，Cu和Si固溶于Al的晶格中，而Sn则固溶于Pb晶格中，并且Al和Pb发生了互溶，形成了Pb(Al）超饱和固溶体；在球磨过程中硬度高的脆性粒子Si难于完全实现合金化。     

Metastable alloy bulk bodies in the Fe–W system prepared by mechanical alloying and shock compression

Bulk bodies of metastable alloys including supersaturated solid solutions and amorphous phases in the iron (Fe)–tungsten (W) system were prepared by mechanical alloying (MA) and shock compression. The X-ray diffraction patterns of the W solid solutions were obtained for the MA-treated powders in the Fe_xW_100−x system with Fe content of x≤30 mol%, and that of Fe solid solution was obtained with an Fe content of x=90 mol%. For the mixed powders with Fe content of 40≤x≤70 mol%, the peaks of Fe completely disappeared, and the amorphous halo-like patterns were observed around the (110) peak of W solid solution. For the mixed powder with an Fe content of 80 mol%, an X-ray diffraction pattern of a two-phase mixture of Fe and W solid solutions was obtained. For the MA-treated powders, the lattice parameters of W solid solutions were smaller than that of pure W, and those of Fe solid solutions were larger than that of pure Fe. No large crack could be observed in shock-consolidated bulk bodies, and the cross sections of the bulk bodies showed a metallic gloss. The X-ray diffraction patterns of shock-consolidated bulk bodies formed in a specific low pressure range did not change significantly from those of the MA-treated powders, which indicated that the metastable phases were successfully consolidated by shock compression without decomposition or recrystallization. Above a driving shock pressure of 40.1 GPa in capsule for the 30:70 mol% Fe–W system and that of 30.5 GPa for the 50:50 mol% Fe–W system, the X-ray diffraction patterns of the recovered bulk bodies showed the appearance of the peaks of Fe₇W₆ intermetallic compound and the peaks of Fe. The recovered specimens of the metastable solid solution phases in the 80:20 mol% Fe–W system did not recrystallize or decompose up to a driving shock pressure of 39.5 GPa. It was confirmed by the Electron Probe Micro Analysis (EPMA) that Fe and W dispersed well at the submicron level in the shock-consolidated bulk bodies. The Vickers hardnesses of the bulk bodies were much higher than those of pure Fe and pure W polycrystals.     

Calculation of free energy of Al-Cu-Li alloy under electric field

Based on Thomas-Fermi model, the interior potential boundary condition with the effect of electric field was defined, the calculation method of free energy for atom cluster under electric field was established. The change of free energy of Al-Cu-Li alloy under the effect of electric field was calculated quantitatively. It is shown that： near the zero electric field and the side of positive electric field, the free energy of Cu4LiAl7 compound at aging temperature 460 K is higher than that of free energy at solid solution temperature 725 K, but once the negative electric field increases to certain degree there will be opposite result. Under the effect of electric field, at 725 K the free energy of Cu4LiAl7 is higher than that of Al-1.0%Li-4.0%Cu, and at 460 K the free energy of compound is lower than that of solid solution. When the copper content in the Al-Li-Cu solid solution is below 5%, under the effect of electric field the free energy of solid solution increases gradually with the increasing of copper content, but the increasing amplitude reduces with the increasing of copper content. The free energy of binary solid solution increases with the addition of lithium, and with the increasing of electric field intensity the free energy margin of two kinds of solid solution becomes bigger.     

Nanosize β-tantalum coatings: Formation, structure, and properties

Using the methods of ion-plasma sputtering and the coprecipitation of ultradispersed Ta and Cu particles, Ta-Cu film coatings have been obtained in the whole range of concentrations. The structural analysis supports the existence of copper solid solutions in -tantalum in the range of 1.5–82.4 at % Cu. The dynamics of the variation of the β-tantalum lattice parameters with increasing copper concentration is described. A computer simulation model for constructing the unit cell of copper solution in -tantalum is proposed. The resistivity of the samples of Ta-Cu alloys at room and liquid-helium temperatures is measured. The alloy obtained is established to possess a chemical resistance to a full-strength nitric acid up to 66.6 at % Cu. The dependence of the electrochemical potential of Ta-Cu coatings on copper concentration is studied. It is shown that the presence of minima at 73.7 at % Cu fairly well corresponds to acid-resistance threshold and is related to the binding-energy changes and to Cu atoms arrangement in β-Ta lattice upon transition from the tantalum-based solid solutions to the copper-based solutions.     

Microstructure of NiCoAlFeCuCr multi-component systems synthesized by mechanical alloying

The present study uses the mechanical alloying method to produce series of binary to senary alloys based on Ni, Co, Al, Fe, Cu, Cr. Milling times are 0, 10, 20 and 30 h and experiments are performed in a high energy ball mill. The results of this investigation show that an FCC solid solution is formed in all the studied systems, but a different phase formation response is presented in each system. A mixture of FCC and BCC solid solutions in quaternary to senary systems, is formed for short milling times. Apparently, the dissolution rate of Fe and Cr into the FCC solid solution, is low. Moreover, it is observed that additions of these elements promote the formation of BCC solid solution, which is stable at temperatures up to ?1273 K. Finally, it is observed that the heat treated products present a mixture of FCC and BCC solid solutions with lattice parameters close to those found in the milled products.     

机械球磨热压烧结Mo-50%Cu合金的组织性能

采用机械球磨-真空热压固相烧结工艺制备Mo-50%Cu(质量分数, 下同)合金,研究机械球磨Mo/Cu复合粉末的组织形貌及热压烧结Mo-50%Cu合金的组织与物理、力学性能。结果表明：热压固相烧结工艺是制备高致密、高Cu含量Mo-Cu合金材料的有效途径;通过机械球磨可以显著细化Mo/Cu复合粉末及烧结态Mo-Cu合金中Mo相组元的尺寸并使其分布均匀化;获得的Mo-50%Cu合金中Mo相细小、均匀弥散分布于Cu基体中,既没有形成对导电性有较大负面影响的网络结构,又能充分发挥Mo相的弥散强化作用,因此,具有优异的物理与力学综合性能     

Fe73.5Cu1Nb3-xTixSi13.5B9 (x=0, 1, 2, 3)合金粉的结构与磁性

将Fe73.5Cu1Nb3-xTixSi13.5B9(x=0,1,2,3)合金快淬带进行高能球磨制成粉末样品,在550℃真空退火1h,研究了磁粉的相结构及磁性。结果表明,随球磨时间延长,不添加Ti的Fe73.5Cu1Nb3Si13.5B9合金中析出晶化相的晶格常数增大。添加Ti的Fe73.5Cu1Nb3-xTixSi13.5B9(x=0,1,2,3)合金在球磨60h后再退火,可以得到单一α-Fe(Si)软磁相,且随Ti含量增大,析出晶化相的晶格常数减小,饱和磁化强度增大、矫顽力降低。     

Fe-Cu二元合金中的B2析出相及时效硬化(英文)

研究了不同成分的Fe-Cu二元合金在过饱和固溶体状态下晶粒尺寸和硬度之间的关系,分析了Cu元素的固溶强化作用。研究了Fe-Cu二元合金的时效硬化现象和Cu元素的析出过程。结果表明Fe-Cu二元合金硬度值增加近一倍。通过透射电镜观察到随时效时间的增加,析出相的尺寸逐渐增大,形状由球形变为棒状。电子衍射花样分析得知,时效处理硬度达到最大值时对应的析出相具有B2型晶体结构,与基体之间保持平行位向关系。透射电镜观察到位错与析出相之间存在典型的引力型交互作用,由于软析出相对运动位错的钉扎效应而使Fe-Cu二元合金得到有效强化。     

Oxidation of Two Ternary Fe–Cu–5 at.% Al Alloys in 1 atm of Pure O2 at 800°C

The oxidation of two two-phase ternary Fe–Cu–Al alloys containing about 5 at.% aluminium, one Fe-rich and one Cu-rich, has been studied at 800°C under 1 atm O₂. The Fe-rich alloy (Fe–15Cu–5Al) shows two parabolic stages, with a large decrease of the parabolic rate constant after about 2 hr. The presence of 5 at.% Al reduces significantly the oxidation rate of this alloy with respect to a binary Fe-Cu alloy of similar composition by forming an external alumina scale. Moreover, the addition of 15 at.% Cu is able to reduce the critical aluminium content needed to form alumina scales with respect to binary Fe–Al alloys. On the contrary, the Cu-rich Fe–85Cu–5 Al alloy presents a single parabolic stage and forms a thick and porous external scale composed of an outermost layer of copper oxides and an inner region containing a mixture of copper and Fe–Al oxides, coupled to the internal oxidation of iron and aluminium. As a result, the oxidation of the Cu-rich ternary alloy at 800°C is much faster than that of the Fe-rich ternary alloy.     

EXAFS STUDY OF THE SHORT RANGE STRUCTURE OF NANOCRYSTALLINE BCC-Fe_(80)Cu_(20) SOLID SOLUTION

1．IntroductionIn re C6C6mwSIs,a①eM dedOf幼iem二on bAn been paid to thelllEchs,ll刀口dan吵ng ofelemental压 and Cu pWders[1一8]．Although匹 and Cu exhibit only vanishingly smallm川ud s0M 50hh1ny uMer出e叫"ill伙山m C0n山t10n8;81旭ie吵%e缸allW8 wl冰uP to60a     

Cu及热处理制度对Al—Mg—Si系合金晶间腐蚀敏感性的影响

采用浸泡腐蚀实验和电化学实验研究了强化元素Cu含量的改变及不同时效制度对Al-Mg-Si合金晶间腐蚀敏感性的影响,并利用XRD和SEM对腐蚀产物的构成及形貌进行了分析与观察,浸泡腐蚀实验结果表明：在峰时效的状态下,在0.5%Cu以上的合金中可观察到明显的晶间腐蚀而且随着Cu含量的增加,合金最大腐蚀深度增加;在欠时效状态下,1%Cu以上的合金中观察到了微弱的晶间腐蚀;在过时效状态下,所有实验合金均只出现点蚀,电化学实验结果表明：随着Cu含量的增加,合金的Ψcorr向正的方向变化,Jcorr增加,欠时效状态下的Ψcorr比峰时效状态下的负,腐蚀电流密度较小。