Auger electron spectroscopy of high-speed-deformed Ni/Cu layers

Ni/Cu double- and multilayers subjected to high-speed deformation were investigated by Auger electron spectroscopy (AES) using depth profiling. Ni and Cu thin films were alternately deposited on a 0.3 mm thick Ni substrate using RF magnetron sputtering. The thickness of the double-layer was 90 nm, while that of the multilayer was 160 nm. High-speed compression was performed using bullet masses from 30.0 to 57.4 g at varying bullet speeds between 16.8 and 48.5 m s⁻¹. The strain rate ranged from 6.7×10⁴ to 8.4×10⁵ s⁻¹. Upon high-speed deformation, the thickness of the Ni/Cu double-layer was reduced to about 80% of its original value. The Cu thin film was compressed to a greater extent relative to the Ni thin film (by about 15%), which may be due to the difference in malleability between the two metals. At a strain rate of 8.4×10⁵ s⁻¹, the Ni/Cu double-layer virtually disappeared. Ni/Cu interdiffusion was enhanced by high-speed deformation. The degree of interdiffusion appeared to be greater at lower strain rates. Cu_0.5Ni_0.5 and Cu_0.75Ni_0.25 thin film alloys formed in the high-speed-deformed multilayer sample, indicating that high-speed compression could potentially be used to prepare thin film metal alloys.     

Precipitation of Cu in Fe–Cu alloys by high-speed deformation

The differences between defect structures in Fe–Cu alloys deformed at the high (4.3×10⁵ s⁻¹) and the low strain rate (67 s⁻¹) were studied. Positron lifetime and coincidence Doppler broadening (CDB) measurements were carried out to investigate the formation of vacancy clusters and Cu precipitates. Both the size of vacancy clusters and the total amount of vacancy-type defects were larger after high-speed deformation at room temperature. Cu precipitation in the specimen deformed at the high-speed stopped for 10 h after annealing at 400 °C, while that in the specimen deformed at the low-speed continued for 100 h. Transmission electron microscopy (TEM) observations showed a heterogeneous distribution of dislocations in the case of low-speed deformation but a homogeneous distribution in the case of high-speed deformation. These results suggested that the sink efficiency for defects was higher in the specimen deformed at the high-speed.     

Cavitation Erosion Behavior of as-Welded Cu12Mn8Al3Fe2Ni Alloy

Cavitation erosion behavior of as-welded Cu12Mn8Al3Fe2Ni alloy in 3.5% NaCl aqueous solution was studied bymagnetostrictive vibratory device for cavitation erosion. The results show that the cavitation erosion resistance ofthe as-welded Cu12Mn8Al3Fe2Ni alloy is much more superior to that of the as-cast one. The cumulative mass lossand the mass loss rate of the as-welded Cu12Mn8Al3Fe2Ni alloy are almost 1/4 that of the as-cast one. SEM analysisof eroded specimens reveals that the as-cast Cu12Mn8Al3Fe2Ni alloy is attacked more severely than the as-weldedone. Microcracks causing cavitation damage initiate at the phase boundaries.     

Positron annihilation study of defects in titanium

Positron annihilation linewidth measurements have been used to study defect behaviour in titanium samples which were first cold-worked and then annealed at temperatures ranging up to 850°C. The line width for a highly deformed high purity (0.9998) sample showed a gradual increase with increasing annealing temperature up to the recrystallization temperature, above which there was a rapid increase. In contrast, a commercially pure (0.9984) sample deformed by 20% displayed a smooth increase in linewidth over the entire annealing range. Hardness measurements correlate reasonably well with the overall trend of the positron lineshape parameter, but the positron annihilation measurements reveal defect changes that occur at temperatures too low to give any observed changes in hardness.     

Fe3O4/Ni复合纳米颗粒的制备及其微波吸收特性

采用电爆炸技术,合成了粒径约为70nm 的Ni纳米颗粒,以3-巯基丙基三甲氧基硅烷偶联剂(MPTS)对Ni颗粒进行表面改性,利用共沉淀法对改性Ni颗粒进行包覆得到核-壳结构的复合纳米颗粒。将获得的复合纳米颗粒作为微波吸收剂, 并以不同比例分散到热固性酚醛树脂中,涂刷在200mm×200mm的金属板上,用RAM反射率远场RCS测量法研究了微波吸收特性。研究表明,核-壳结构Fe₃O₄/Ni复合颗粒作为微波吸收剂,在相同质量比条件下,其微波吸收性能明显优于纯Ni纳米颗粒或Fe₃O₄纳米颗粒的情况,并且在Fe₃O₄/Ni核-壳结构复合纳米颗粒中随着镍含量的提高,微波吸收增强,而随着Fe₃O₄含量的增加,微波吸收频段向高频段移动。     

A study of vacancy-type defects in pure and boron-doped Ni3Al alloys

Positron lifetimes have been measured for two sets of pure and boron-doped Ni₃Al alloys. The alloys were large-grain polycrystals and had compositions of Ni_75+xAl_25−x (x = −1, 0, + 1) with 0, 100 and 500 wt ppm boron added. Lifetime parameters for samples of composition Ni_75+xAl_25−x (x= ± 1) with 0 and 500 wt ppm boron added were measured after initial thermal conditioning and after a subsequent cold-work anneal treatment. Positron trapping (≈20%) was observed in all unprocessed alloys. The vacancy concentration was calculated to be ≈ 5 × 10⁻⁶ and showed little, if any, systematic dependence on either alloy composition or boron concentration. Cold-worked fully annealed samples contained no detectable vacancies, i.e. the trapped state intensity was observed to be zero. The results are at variance with previously published data. During the annealing procedure (> 350°C) carbon was observed to diffuse out of the cold-worked samples. It is therefore possible that carbon stabilizes vacancies in Ni₃Al alloys. There is, however, no evidence to suggest that boron interacts with constitutional vacancies in Ni₃Al.     

Positron lifetime calculations on vacancy clusters and dislocations in Ni and Fe

Positron lifetime calculations have been performed on vacancy clusters (stacking fault tetrahedra (SFT), vacancy loops), such clusters on dislocation line, interstitial clusters, such clusters on a dislocation line and dislocation line itself in order to investigate the so-called intermediate lifetimes observed in the experiments, namely, positron lifetimes between that at a matrix and that at a single vacancy. Before lifetime calculations, various defects were constructed in the model lattices and were relaxed completely to obtain the stable atomic structure by using N-body potentials. Then positron lifetime calculation was carried out for each defect. It was shown that positron lifetime for a SFT in Ni dependes on its size and becomes smaller with increasing the size. The positron wave function is mainly localized at the corner of a SFT, which gives rather lifetime, e.g., 130 ps for V₂₈, but when the cluster size is small, e.g., less than 10 vacancies, it gives a rather longer lifetime, e.g., 177 ps for V₆ because of the wave function localized at the inner space of a cluster. These behaviours are consistent with the experimental results. It was also found that the positron lifetime on a dislocation line and that at a jog are short (113 and 119 ps, respectively for Ni, 117 and 117 ps, respectively for Fe), close to the lifetime at matrix (110 ps for both Ni and Fe) and in these cases trapping potentials for a positron are shallow both for Ni and Fe.     

雾化Al63Cu25Fe12粉末的热处理过程中的相变分析

采用高压惰性气体雾化水冷的快速凝固的方式制备各种粒度(175～375μm,75～175μm,＜75μm)的Al63Cu25Fe12准晶粉末的不同温度(650℃,750℃,850℃)下的热处理,总结出不同的处理条件下粉末内部相的转变情况,发现Al 63Cu25Fe12粉末中相的变化主要集中在β(τ)相的降低和准晶I相的生成以及ω相的形成,随着热处理时间的增加,β(τ)相迅速降低,准晶I相增加;而且在850℃保温12h的真空热处理后,向准晶相的转变较充分,可以得到几乎单一的准晶组成.     

Influence of nano-particle size on the oxidation behaviour of Al,Fe and Cu

Abstract

The addition of ultra-fine and nano-sized particles in composite materials influences their properties. In order to understand the influence of the nano-size of metal particles on the oxidation behaviour, a series of in situ studies by thermogravimetry (TG) and high temperature X-ray diffraction (XRD) was performed on Al, Fe and Cu during heating with post oxidation analysis by field emission – scanning electron microscope (FE-SEM). The oxidation reaction depends, for all three studied metals, on the particle size both in regard to transient oxide formation and formation temperatures. On a nano-scale Al forms θ-Al₂O₃ and γ-Al₂O₃ simultaneously at 500°C, but both of these oxides transform to α-Al₂O₃ at 975°C producing nano-scaled oxide particles. Aluminium particles with sizes from 2 to 25 μm form α-Al₂O₃ only, starting at temperatures close to the melting point. Nano-sized Fe forms on heating from 340°C α-Fe₂O₃ only and no other oxides. On nano-sized Cu particles the formation of Cu₂O starts at 140°C, transforming completely to CuO at 300°C.     

Ultrasonic Welding of Ni and Cu Sheets

Ultrasonic metal welding is widely used in various fields due to its ability to weld a variety of materials such as new materials and sheet structures. In this study, a special horn with four-point tips was developed for the ultrasonic welding of Ni and Cu sheets used as electrode materials of the secondary cell. The effects of welding parameters (welding time, clamping pressure, and vibrational amplitude) on weldability were investigated using the developed horn. The weldability of Ni/Cu sheet was assessed via the tensile test, scanning electron microscope observation, and EDX-ray analysis of the weld zone. Experimental results showed that the optimal welding parameters were a welding time of 0.25 s, pressure of 0.20 MPa, and vibrational amplitude of 80%, with a welding strength of 87.45 N under these conditions. It was also confirmed that solid-state diffusion by vibrational and frictional heat was clearly generated at the welding interface under good welding conditions.     

ICP-AES内标法测定不锈钢中Cr、Ni、Cu、Mn

本文采用王水溶样,酸化水稀释,ICP-AES内标法快速测定不锈钢中Cr、Ni、Cu、Mn的含量。研究了溶液的酸度、基体浓度以及内标线选择,确定了试样分析的最佳工作条件。方法回收率99～115％,RSD2.6—6.3％。标准参考物的分析结果与推荐值基本一致。     

微量Y对铸造Ni50Al20Fe30合金组织与性能的影响

研究了不同Ｙ含量对铸造Ｎｉ５０Ａｌ２０Ｆｅ３０合金与性能的影响。结果表明,微量Ｙ的加入可以改善Ｎｉ５０Ａｌ２０Ｆｅ３０合金的强强度与塑性。Ｙ含量为０．０５ｗｔ％－０．１ｗｔ％是合金最佳含量范围。微量Ｙ的加入影响合金的共晶区,可明显改变合金的微观组织形态。     

Ion implantation effect on atomic structure of deformed Si, Ir, W, Ni and Cu

It has been revealed, that in Ir subjected to severe plastic deformation, an ultrafine grained structure (UFG) is formed (the grain size of 20-30 nm). Practically no defects have been detected within the grains, while, in the case of Ar⁺ implantation, the subgrain structure with characteristic sizes of about 3-5 nm is formed; defects have been detected within subgrains.The subgrain structure was also revealed in UFG Ni and Cu after severe plastic deformation (SPD) (subgrain size of 3-15 nm), but in the latter case the observed boundary region is broader and subgrain is highly disoriented.     

（Fe,Ni）_4N包覆（Fe,Ni）纳米复合粒子的微波吸收特性

以直流电弧等离子体法制备（Fe,Ni）的纳米粒子为前驱体,分别在350℃、400℃和450℃的氨气气氛中,通过热氨解反应合成（Fe,Ni）_4N包覆（Fe,Ni）纳米复合粒子。应用XRD,TEM,VSM,微波矢量网络分析仪对纳米粒子相成分、形貌、磁性和电磁参数进行了分析。结果表明,形成了（Fe,Ni）_4N包覆（Fe,...     

Ni/Cu双金属纳米线非模板法制备研究

在外加磁场作用下,制备出Ni纳米线,再以Ni纳米线为载体,利用Ni置换溶液中的Cu2+制备出Ni/Cu双金属纳米线,并进行扫描电镜(SEM)、透射电镜(TEM)、X射线衍射(XRD)、能谱(EDS)等表征。结果显示样品线性较好、尺寸均匀,约为200 nm,组成为Ni单质和Cu单质,均为面心立方结构,其含量分别为62.34%与36.37%(质量分数)。     

Preparation of super-hydrophobic Cu/Ni coating with micro-nano hierarchical structure

Micro-nano hierarchical structured Cu/Ni multilayer coating was prepared by a simple two-step method combined with electroless and electro deposition. Structure and morphology of the as-prepared Cu/Ni multilayer coating were analyzed by X-ray diffractometer and field emission scanning electron microscopy. Results show that micro-nano Cu/Ni coating is well-crystallized and exhibits sea cucumber-like microstructure with Ni nanocone arrays uniformly dispersed perpendicular to the circular conical surface of Cu cone. Static contact angles were measured to investigate the surfaces' wettability. The result reveals that the Cu/Ni multilayer coating is super-hydrophobic, of which the static contact angle with test liquid (water) was 156°(> 150°).Due to its super-hydrophobic property and unique shape, Cu/Ni multilayer coating is expected to have extensive practical applications.     

Different Diffusion Behavior of Cu and Ni Undergoing Liquidesolid Electromigration

The diffusion behavior of Cu and Ni atoms undergoing liquidesolid electromigration（L-S EM） was investigated using Cu/Sn/Ni interconnects under a current density of 5.0 103A/cm2 at 250℃. The flowing direction of electrons significantly influences the cross-solder interaction of Cu and Ni atoms, i.e., under downwind diffusion, both Cu and Ni atoms can diffuse to the opposite interfaces; while under upwind diffusion,Cu atoms but not Ni atoms can diffuse to the opposite interface. When electrons flow from the Cu to the Ni, only Cu atoms diffuse to the opposite anode Ni interface, resulting in the transformation of interfacial intermetallic compound（IMC） from Ni3Sn4into（Cu,Ni）6Sn5and further into [（Cu,Ni）6Sn5t Cu6Sn5], while no Ni atoms diffuse to the opposite cathode Cu interface and thus the interfacial Cu6Sn5 remained.When electrons flow from the Ni to the Cu, both Cu and Ni atoms diffuse to the opposite interfaces,resulting in the interfacial IMC transformation from initial Cu6Sn5into（Cu,Ni）6Sn5and further into[（Cu,Ni）6Sn5t（Ni,Cu）3Sn4] at the anode Cu interface while that from initial Ni3Sn4into（Cu,Ni）6Sn5and further into（Ni,Cu）3Sn4at the cathode Ni interface. It is more damaging with electrons flowing from the Cu to the Ni than the other way.     

Comparison of Structure and Conductivity of Multiwall Carbon Nanotubes Obtained over Ni and Ni/Fe Catalysts

Multiwall carbon nanotubes (MWNT) were produced by pyrolysis of acetonitrile (CH₃CN) on metallic particles of Ni and Ni/Fe at 850°C. The special program for statistical treatment of electron micrograph images was developed. Research of diameter distribution of MWNT grown over different catalysts was carried out. Two kinds of carbon nanotubes with different diameter and microstructure are formed on Ni catalyst. The MWNT with smaller diameter and cylindrical packing of layers were found to have the higher conductivity.     

Comparison of Structure and Conductivity of Multiwall Carbon Nanotubes Obtained over Ni and Ni/Fe Catalysts

Abstract

Multiwall carbon nanotubes (MWNT) were produced by pyrolysis of acetonitrile (CH₃CN) on metallic particles of Ni and Ni/Fe at 850°C. The special program for statistical treatment of electron micrograph images was developed. Research of diameter distribution of MWNT grown over different catalysts was carried out. Two kinds of carbon nanotubes with different diameter and microstructure are formed on Ni catalyst. The MWNT with smaller diameter and cylindrical packing of layers were found to have the higher conductivity.     

（Ni,Fe）Al金属间化合物的快速凝固组织与室温塑性

用单辊快速凝固法制备（ＮｉＦｅ）Ａｌ金属间化合物并研究其组织与室温塑性。结果表明，Ａｌ－４５Ｎｉ－５Ｆｅ（原子分散）在快速凝固条件下可形成内部为亚微米级针状亚晶的等轴晶粒，具有高达３．１％的弯曲塑性，Ａｌ－３５Ｎｉ－１５Ｆｅ和Ａｌ－２５Ｎｉ－２５Ｆｅ的快凝组织则为柱状晶，弯曲塑性仅有１．１％１．０％，针状亚晶是一定成分的（Ｎｉ，Ｆｅ）Ａｌ在快速凝固条件下形成的亚稳相，其形成机制和快速凝固过程中原子