Microstructure and penetration behavior of electroformed copper liners of shaped charges during explosive detonation deformation

The microstructure in the electroformed copper liners of shaped charges prepared with different electrolytes was studied by Scanning Electron Microscopy （SEM） and Electron Backscattering Kikuchi Pattern （EBSP） methods. SEM observations revealed the existence of columnar grains in electroformed copper liners of shaped charges formed by electrolyte without any additive and the average grain size is about 3 μm. When an additive is introduced to the electrolyte, the grains formed in the copper liners become equiaxed and finer. EBSP results show that the columnar grain grown during electroformation has the most preferential growth direction, whereas a micro-texture does not exit in the specimen prepared by electrolyte with the additive. Further, explosive detonation deformation experiments show that penetration depth is dramatically improved when the electroformed copper liners of shaped charges exhibit equiaxed grains.     

Dynamic recrystallization of electroformed copper liners of shaped charges in high—strain—rate plastic deformation

The microstructures in the electroformed copper liners of shaped charges after high-strain-rate plastic deformation were in vestigated by transmission microscopy(TEM).Meanwhile,the orientation distribution of the grains in the recovered slug was examined by the electron backscattering Kikuchi pattern(EBSP) technique.EBSP analysis illustrated that unlike the as-formed electroformed copper liners of shaped charges the grain orientations in the recovered slug are distributed along randomly all the directions after undergoing heavily strain deformation at high-strain rate.Optical microscopy shows a typical recrystallization structure,and TEM examination reveals dislocation cells existed in the thin foil specimen.These results indicate that dynamic recovery and recrystallization occur during this plastic deformation process,and the associated deformation temperature is considered to be higher than 0.6 times the melting point of copper.     

The properties of the sintered copper powder liner

In order to study the properties of sintered copper powder shaped charge liner, the copper powder, whose particle size was below 20 μm, was chosen as the main material. The mixed powders were directly pressed into the desired shape of the shaped charge liner by the top direct-pressure way. The microscopic morphology of the spinning shaped charge liner, the sintered and non-sintered powder liners, and the particle properties of the copper powder were studied with scanning electron microscopy. The experimental results showed that the irregular copper powder could get together effectively and sintering could improve the compactness of the powder liner effectively. The wall thickness and density of the non-sintered and sintered liner were also tested, and it shows that sintering causes the wall thickness thinned and the density improved. The penetration depths of non-sintered powder liner, sintered powder liner and the spinning copper plate liner were tested with different standoff respectively, showing that the penetration properties of sintered powder liner are well.     

Structure and internal stress of Au films deposited on SiO2／Si（100） andmica by dc sputtering

Au films with a thickness of about 300 nm were deposited on SiO2/Si(100) and mica substrates by dc sputtering. X-ray diffraction spectroscopy and field emission scanning electron microscopy were used to analyze the structure and internal stress of the Au films. The films grown on SiO2/Si(100) show a preferential orientation of [111] in the growth direction. However the films grown on mica have mixture crystalline orientations of [111], [200], [220] and [311] in the growth direction and the orientations of [200] and [311] are slightly more than those of [111] and [220]. An internal stress in the films grown on SiO2/Si(100) is tensile. For Au films grown on mica the internal stresses in the [111]-and [311]-orientation grains are compressive while those in the [200]- and [220]-orientation grains are tensile. Au films grown SiOJSi(100) have some very large grains with a size of about 400 nm and have a wider grain size distribution compared with those grown on mica.     

Preparation and Characterization of Amorphous Silicon Oxide Nanowires

Large-scale amorphous silicon nanowires （SiNWs） with a diameter about 100 nm and a length of dozens of micrometers on silicon wafers were synthesized by thermal evaporation of silicon monoxide （SiO）. Scanning electron microscope （SEM） and transmission electron microscope （TEM） observations show that the silicon nanowires are smooth. Selected area electron diffraction （SAED） shows that the silicon nanowires are amorphous and en-ergy-dispersive X-ray spectroscopy （EDS） indicates that the nanowires have the composition of Si and O elements in an atomic ratio of 1：2,their composition approximates that of SiO2. SiO is considered to be used as a Si sources to produce SiNWs. We conclude that the growth mechanism is closely related to the defect structure and silicon monoxide followed by growth through an oxide-assisted vapor-solid reaction.     

Effect of grain size on α-variant selection in a ZrTiAlV alloy

Local crystallographic orientation characteristics of grains with different sizes in a ZrTiAlValloy after interrupted cooling from βphase region are investigated by electron backscatter diffraction(EBSD) technique. A statistical analysis of EBSD data shows that bigger parent β grains present weaker variant selection than smaller grains. The relevant influences are studied by comparing the nucleation behavior of grain boundary α(GBα) and succedent growth stage in varisized grains. In-depth analysis indicates that the deviation between pole of GBα and common pole of adjacent parent β grains is responsible for the smaller degree of variant selection inside the bigger parent β grains. The formation of more than one GBα type at the β/β grain boundary with common pole in bigger grains results in obstructing each other for these variants during the following growth stage, while only one type of GBα nucleate at the β/β grain boundary with common pole in smaller grains and it can freely grow into the interior of the grains, leading to stronger variant selection in smaller β grains.     

Preparation of copper nano-wires by template synthesis method

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.     

Microstructure and strengthening parameters of ultra—thin hot strip of low carbon steel

The microstructure and precipitation mechanism of ultra-thin hot strip produced by CSP technology were analyzed by electron back scattered diffraction(EBSD),H-800 transmission electron microscope(TEM) and thermodynamics theory.The EBSD results show that the finishing hot rolling microstructures are mixture of recrystallized and deformed austenite.After phase transformation,ferrite grains embody subastructures and dislocations that led ultra-thin hot strip high strength and relatively low elongation rate.TEM observations show that there are a lot of fine and dispersive precipitates in microstructures.Most of aluminium nitrides are in grains.While coexisted precipitates of MnS along grain boundaries,Coexisted precipitates compose cation-vacancy type oxides such as Al2O3 in the core,while MnS at the fringe of surface.At the same time,reasons for microstructure refinement and strengthening effect were invstigated.     

Cellular automata modelling of grain coarsening during reheating——Ⅱ. Abnormal grain growth

The 2-dimensional cellular automata (CA) simulation technique has been utilized to investigate the abnormal grain coarsening. The growth of abnormal grains is modelled under this assumption that different grains have different boundary energies and boundary mobilities. As temperature increases, some grains may first get rid of the particle pinning effect. Thus a high probability is obtained for atoms to jump over the boundary, so that they can consume other primary retained grains quickly. From the simulation,the characteristics of the abnormal grain coarsening under different conditions are demonstrated successfully. An experiment has also been carried out to reflect the abnormal grain coarsening on the microalloy steel. Simulation results are quite close to the experimental evidence.     

Microstructural formation of semi-solid AZ91D alloy stirred by electromagnetic field

With the help of an electromagnetic stirring device, alloy melt quenching and EBSD (electron back scatter diffraction)analysis technology, the microstructure of the semi-solid AZ91D magnesium alloy slurry stirred by rotational electromagnetic field under different stirring power conditions has been studied. The results show that the size of primary α-Mg phase is reduced obviously when the solidifying alloy melt is stirred by rotational electromagnetic field, moreover, the primary α-Mg grains are changed to fine rosette grains or spherical grains which are proved to belong to the different grains in three-dimension by the EBSD analysis technology. The results also show that the stirring power is an important processing parameter in the preparation of the semi-solid AZ91D magnesium alloy slurry. The larger the stirring power, the finer the primary α-Mg grains, the less the rosette primary α-Mg grains, and the more the spherical primary α-Mg grains. Theoretical analysis indicates that a stronger flow motion leads to a more even temperature field and solute field and a stronger man-made temperature fluctuation in the alloy melt so that the specially fine rosette and/or spherical primary α-Mg grains are formed in the semi-solid AZ91D magnesium alloy slurry.     

Microstructural evolution in electroformed nickel shaped-charge liners with nano-sized grains undergone deformation at ultrahigh strain rate

Nickel shaped-charge liners with nano-sized grains were prepared by the electroforming technique, and the deformation at ultrahigh strain rate was performed by explosive detonation. The as-formed and post-deformed microstructures of electroformed nickel shaped-charge liners with nano-sized grains were observed by means of transmission electron microscopy, and the orientation distribution of the grains was analyzed by the electron backscattering pattern (EBSP) technique. The melting phenomenon in the jet fra...     

Mechanical properties of electroformed copper layers with gradient microstructure

The electroformed copper layer with gradient microstructure was prepared using the ultrasonic technique.The microstructure of the electroformed copper layer was observed by using an optical microscope (OM) and a scanning electron microscope (SEM).The preferred orientations of the layer were characterized by X-ray diffraction (XRD).The mechanical properties were evaluated with a Vicker's hardness tester and a tensile tester.It is found the gradient microstructure consists of two main parts:the outer part (fa...     

纯镍多晶体循环形变过程中位错结构的TEM研究

本文对纯镍多晶体循环形变过程中位错结构,特别是驻留滑移带(PSB)的形成及特性进行了TEM研究,并用选区电子衍射确定了晶粒膜面及其它晶体学取向。结果表明在循环饱和的开始点附近已观察到以梯状花样为特征的PSB;证明循环硬化阶段的末端基本上与PSB的成核相对应。并证实PSB结构是一种体效应。     

Microstructure evolution of single crystal copper wires in cold drawing

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     

一维Cu@C核壳结构纳米复合材料的制备与表征

以氯化铜作为铜源,六次甲基四胺(HMT)作还原剂和碳源,十六烷基三甲基溴化铵(CTAB)作表面活性剂,在水热条件下合成了一维Cu@C核壳结构纳米复合材料,并进行了表征分析。结果表明,制备的Cu@C核壳结构纳米复合材料为立方相铜晶体,无杂质出现。长度在几微米到十几微米,直径大约200~400 nm。产物由铜、碳2种元素构成;从透射电镜照片可以清楚的看出明暗对比,表明产物的核壳结构。在反应过程中,十六烷基三甲基溴化铵(CTAB)起到了形状控制剂的作用。     

Cu-Zr合金定向凝固组织的研究

采用定向凝固方法制备了Cu 12 .2 5Zr自生复合材料,并通过扫描电镜(SEM)、透射电镜(TEM)和X射线衍射等方法对定向凝固组织进行了研究.结果表明,在温度梯度一定的前提下,生长速度对定向凝固组织的形貌有着重要的影响,随着生长速度的增加,凝固组织由层片状依次转化为棒状、树枝状和集群状组织;在所制备的Cu 12 .2 5Zr自生复合材料中,第2相主要是Cu5Zr,并且Cu5Zr与基体α(Cu)之间存在着一定的取向关系,另外还有少量的Cu8Zr3 相和Cu10 Zr7相;在Cu 12 .2 5Zr合金枝晶端部存在明显的Zr元素富集.     

Effects of submicron diamonds on the growth of copper in Cu-diamond co-deposition

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.