机械合金化Fe_(40)Ni_(40)Si_(20)纳米晶固溶体

机械合金化方法制备了Fe—Ni—Si三元系合金,利用X射线衍射仪研究了合金化过程中的 相变行为,计算了晶粒尺寸及微观应变。结果表明,经36小时球磨可形成α-Fe(bcc)和γ-Fe(fcc) 两相混合纳米晶固溶体;继续球磨,过饱和α相逐渐分解并向γ相转化,72小时后可得单相γ-Fe纳 米晶固溶体。球磨晶粒尺寸可达12 nm,微观应变随球磨时间先增加后减小。     

金属氮化物的球磨制备方法

采用自制的可充一定压力气体的球磨装置,在抽真空后,对装有一定量的纯金属Ｚｒ,Ｎｂ的球磨罐内充入０．３ＭＰａ的氮气,并进行球磨氮化反应ＸＲＤ,ＴＥＭ结果表明,在室温下,纯金属均发生氮化反应,并生成相应稳定的氮化物,对生成物的颗粒尺度及相结构进行了表征,并对其反应机理给出了相应的讨论。     

机械合金化制备β-FeSi2热电材料

采用机械合金化结合氩气退火法成功制备了β-FeSi2热电材料,并用XRD、SEM对不同球磨时间后的Fe-Si粉体进行结构及形貌表征.试验结果表明:随着球磨时间的延长,颗粒不断细化,最后可得到Fe- Si纳米晶合金;球磨20 h后,Fe衍射峰宽化而Si衍射峰逐渐减弱,形成α-Fe(Si)过饱和固溶体;球磨120 h后出现合金ε-FeSi、β-FeSi2相;调整Si/Fe原子比例为2.3,对球磨120h后合金粉末在800℃退火20h,可以得到单相β-FeSi2热电材料.     

热电材料CoSi化合物的机械合金化合成

采用高能行星球磨的方法研究了等计量比CoSi的纯元素混合粉末的机械合金化过程.对球磨不同时间粉末的结果分析和观察表明:球磨产物为单相CoSi化合物,其晶粒尺寸随球磨的时间延长而减小,没有发生非晶化,并对此进行了热力学分析.     

Structural characterization of AA 2024-MoSi2 nanocomposite powders produced by mechanical milling

Nano-sized MoSi₂ powder was produced successfully from commercially available MoSi₂ by a mechanical milling process carried out for 100 h, and mechanical alloying was employed to synthesize AA 2024-MoSi₂ nanocomposites. The effects of MoSi2 reinforcement and mechanical milling on the structure, morphology, and iron contamination of the produced materials were investigated using X-ray diffraction, scanning electron microscopy, and atomic absorption spectrometry. It is revealed that the morphology of the aluminum alloy changes continuously during milling from spherical to plate-like, irregular, and finally equiaxed. The presence of MoSi₂ reinforcement accelerates the milling process and results in a smaller average particle size. The Williamson-Hall method determined that the crystallite size of the aluminum alloy in the composite powder is smaller than that of the unreinforced alloy at the same milling time and this size reaches 45 nm after 16 h milling time. The Fe contamination content is higher for the nanocomposite in comparison with the unreinforced alloy because of the wearing role of MoSi₂ hard particles.     

高能球磨-热压烧结制备定向排布板状WC硬质合金

采用高能球磨辅助特殊的热压烧结工艺制取定向排布板状WC硬质合金,研究了烧结温度和球磨时间对板状WC晶粒形成及其定向排布的影响.研究结果表明:烧结温度越高,越有利于晶粒粗化,形成大块板状WC晶粒;高能球磨中引入的缺陷是促进WC晶粒长径比提高的主要原因;WC晶粒的均匀性、粒径和长径比是影响其定向排布的主要因素.制备定向排布板状WC硬质合金是同时提高硬质合金硬度和韧性的有效方法.     

机械研磨对FeCuNbSiB微晶合金组织结构的影响

机械研磨对ＦｅＣｕＮｂＳｉＢ微晶合金组织结构的影响张建强，吴炳尧朱建军（东南大学机械工程系，南京２１００１８））（电子工业部第十四研究所，南京２１０００３）ＦｅＣｕＮｂＳｉＢ微晶合金是指由该材料制得的非晶带在略高于晶化温度退火而形成的具有纳米晶相和残...     

Al1-xFex混合粉末的机械合金化

对Al1-Fe(x-5，50，75at％)混合粉末进行了球磨，用X射线、电镜等分别研究了球磨粉末的结构和形貌．得到了Al95Fe5中AI相的有效晶粒尺寸和Alt-xFex的平均晶粒尺寸随球磨时间的变化，其变化规律是先增大，再减小，最后达到稳定值而不再变化．得到了Al95Fe5中的晶格畸变，也出现交替变化．对于Al1-xFex混合粉末，Al，Fe成分越接近，机械合金化过程中扩散越易于进行．球磨样品晶粒尺寸越小，聚集的趋势越小．固溶体的溶解度与混合粉末的成分有关．     

NiTi长纤维增强Mg合金复合材料及其制备

采用球磨／热压工艺制备出一种NiTi长纤维增强Mg合金复合新材料．实验表明该复合材料具有较高的密度和硬度，基体组织均匀，长纤维没有受到损伤，与基体之间的界面清晰，没有观察到界面反应层，没有MgO形成．制备工艺简单，可操作性强．     

W80X20合金球磨纳米化研究

机械球磨是一种制备纳米材料的新工艺，它方法简单、适应性强，因而具有广泛的应用前景。该文对比了4种W合金在球磨过程中晶粒尺寸随时间的变化规律，并结合不同金元素的熔点分析，提出了W系合金球磨纳米化的塑性变形－扩散双机制。     

NiTi形状记忆合金振动感知与主动控振研究

分析了复合于基体材料或嵌入机械结构中的ＮｉＴｉ丝对动、静应变的感知性能，基于ＮｉＴｉ形状记忆合金的振动感知和驱动特性，实现了机械系统振动的智能化控制，建立起机械系统的动力学模型。基于机械系统参数时变的特点，应用时频分析方法很好地描述了机械系统非平稳振动响应的过程，结果表明，ＮｉＴｉ形状记忆合金可灵敏地感知动、静应变，并可迅速作出反应，有效控制振动。     

Morphology and microstructure characterization of 95W-3.5Ni-1.5Fe powder prepared by mechanical alloying

Morphology and microstructure characterization of 95W-3.5Ni-1.5Fe powder prepared by mechanical alloying@Islam S.Humail$State Key Laboratory for Advanced Metals and Materials,Materials Science and Engineering School, University of Science and Technology B…     

Preparation of NiO nanoparticles from Ni（OH）2-NiCO3-4H2O precursor by mechanical activation

A mechanical activation process was introduced as a facile method for producing nickel oxide nanopowders. The precursor compound Ni（OH）2-NiCO3-4H2O was synthesized by chemical precipitation. The precursor was milled with NaCl diluent. A high-energy ball milling process led to decomposition of the precursor and subsequent dispersal in NaCl media. Nickel oxide nanocrystalline powders were produced by subsequent heat treatment and water washing. Milling rotation speed, milling time, ball-to-powder ratio （BPR）, and nickel chlo-ride-to-precursor ratio were introduced as influential parameters on the wavelength of maximum absorption （λmax）. The effects of these pa-rameters were investigated by the Taguchi method. The optimum conditions for this study were a milling rotation speed of 150 r/min, a mill-ing time of 20 h, a BPR of 15/1, and a NaCl-to-powder weight ratio （NPR） of 6/1. In these conditions,λmax was predicted to be 292 nm. The structural properties of the samples were determined by field emission scanning electron microscopy, X-ray diffraction, and energy dispersive spectrometry.     

Fe60 Co20 C20超细合金粉末的结构和磁性能研究

采用机械合金化方法制备出Fe60Co20C20超细合金粉末,对不同球磨时间的样品进行X射线衍射和磁滞回线的测量.X射线衍射分析结果表明:样品在球磨20 h后开始部分非晶化,在Fe-Co合金中加入C可促使其形成非晶;样品的晶粒尺寸随球磨时间的增加而减小,在一定的机械合金化条件下可获得Fe60Co20C20的非晶态超细合金粉末.VSM研究结果表明:球磨初期,样品的矫顽力增加;球磨20 h后,随着晶粒尺寸的降低矫顽力降低.机械球磨后晶粒尺寸是影响样品磁性能的主要因素.     

高能球磨纳米镍粉制备块体材料的研究

采用高能球磨法制备了纳米晶Ni粉末,对纳米晶粉末进行预压烧结,获得纳米晶镍块体材料.采用显微分析方法研究了纳米晶粉末和块体材料的显微组织结构.试验结果表明,高能球磨所得镍粉平均晶粒尺寸为10 nm;预压烧结块体的平均晶粒尺寸在100 nm以下;块体相对致密度在烧结温度为0.6Tm时达到最大值.     

机械合金化制备Nb_3Al超导体的工艺研究

利用机械合金化方法制备了一系列不同的Nb3Al块材,研究了球磨时间及退火温度对Nb3Al超导体成相及超导性能的影响,并采用X射线衍射仪、扫描电子显微镜和磁学测量系统等详细分析了不同制备条件下Nb3Al超导体的相成分、微观组织结构,以及超导性能的变化.结果表明:将Nb和Al粉末混合后,利用高能球磨设备,球磨1 h即可以生成Nb(Al)ss过饱和固溶体;当球磨时间增加到10 h时,样品粉末发生了非晶化.通过调节球磨时间、退火温度,成功制备出超导起始转变温度达到15.3 K的单相Nb3Al超导体.     

机械合金化制备Fe-B-Si纳米晶粉末

该文采用机械合金化方法制备Fe50B14Si36合金纳米晶材料。球磨过程中对该合金进行取样，通过X射线衍射分析，及晶粒尺寸和点阵常数的计算，发现该合金在球磨300h前晶粒尺寸迅速下降，能够实现纳米化；球磨时间小于300h时材料的矫顽力增加，而当球磨时间超过300h时矫顽力下降，材料的软磁性能增强。     

MnFeP0.6 Si0.25 Ge0.15粉末样品的制备及X射线衍射分析

使用机械合成法制备了MnFeP0.6Si0.25Ge0.15粉末样品,研究了试样颗粒大小和半峰宽随球磨时间的变化关系.X射线粉末衍射分析表明,该样品退火后为Fe2P结构,样品密度ρ=6.655 g/cm3,颗粒大小D=43.2 nm,晶格畸变量Δd/d=0.053 818,表明在球磨过程中存在一定的晶格畸变.球磨100 h后,试样颗粒大小达到纳米量级.     

Mechanical milling assisted by electrical discharge

Mechanical milling is an effective technique for the preparation of fine metallic and ceramic powders and can also be used to drive a wide range of chemical reactions. Milling devices include planetary machines, attritors and vibrational mills; products include amorphous, nanocrystalline and quasicrystalline materials, supersaturated solid solutions, reduced minerals, high-surface-area catalysts and reactive chemicals. During milling, solid-solid, solid-liquid and solid-gas reactions are initiated through repeated deformation and fracture of powder particles. A separate materials synthesis and processing technique involves reacting a material in a gas atmosphere under an electrical discharge. Here we show that the application of low-current, high-voltage electrical impulses during milling can result in both faster reactions and new synthesis and processing routes. We demonstrate the effects of glow (cold) and spark (hot) discharge milling on particle fracture for brittle, low-conductivity materials and ductile metals. Glow discharge milling was found to promote solid-gas reactions whereas spark discharge milling promotes fast fracturing, recrystallization, mineral reduction and solid-solid reactions.     

Preparation of high-performance ultrafine-grained AISI 304L stainless steel under high temperature and pressure

Bulk ultra-fine grained (UFG) AISI 304L stainless steel with excellent mechanical properties was prepared by a high-temperature and high-pressure (HTHP) method using nanocrystalline AISI 304L stainless steel powders obtained from ball milling. Samples were sintered in high-pressure conditions using the highest martensite content of AISI 304L stainless steel powders milled for 25 h. Analyses of phase composition and grain size were accomplished by X-ray diffraction and Rietveld refinement. By comparing the reverse martensite transformation under vacuum and HTHP treat, we consider that pressure can effectively promote the change in the process of transformation. Compared with the solid-solution-treated 304L, the hardness and yield strength of the samples sintered under HTHP are considerably higher. This method of preparation of UFG bulk stainless steel may be widely popularised and used to obtain UFG metallic materials with good comprehensive performance.