纳米晶粉末Mn70Bi30的机械合金化合成

采用机械合金化的方法制备出Ｍｎ７０Ｂｉ３０纳米晶粉末，通过Ｘ射线衍射和饱和磁经强度的测量，研究了球磨过程中样品的结构和磁性能的变化，Ｘ射线衍射的测量结果表明，Ｂｉ在Ｍｎ中的固溶度随球磨时的增加而增加，球磨８０ｈ后Ｂｉ的固溶度趋于稳定，此时粉末的晶粒尺寸达到１４ｎｍ，球磨初期，样品的饱和性磁化强度（σｓ）随球磨时间的增加而增加，球磨１５ｈ，σｓ从零曾加到最大值，之后，σ随球磨时间的中而减小，饱和磁化     

机械合金化纳米晶合金Ni50Bi50的结构和磁性

研究了Ｎｉ５０Ｂｉ５混合粉末在机械合金化过程中结构和磁性的变化。Ｘ射线衍射、差示扫描量热分析和比饱和磁化强度的测量结果表明：混合粉末的晶粒尺寸随球磨时间的增加而减小。球磨２００ｈ时，样品的晶粒尺寸为１５ｎｍ。机械合金化可以提高Ｂｉ在Ｎｉ中的固溶渡。     

机械球磨3%C-Cu复合粉末的微观组织

为了获得具有良好微观组织的C-Cu复合粉末,以利于后续的压制、烧结和挤压等工艺,用机械球磨方法制备了3%C-Cu(质量分数)复合粉末.运用扫描电镜、背散射和X射线衍射等分析手段研究了该复合粉末的微观组织随球磨时间的演变规律.实验结果表明,随着机械球磨时间的增加,Cu颗粒由树枝状转变为层片状、块状,最后转变为近球形.球磨2 h,复合粉末中的石墨衍射峰消失.随着球磨的进行,复合粉末中Cu的微观应变逐渐增大.经3 h的机械球磨获得了晶粒尺寸约为20 nm的Cu纳米晶,说明该方法可以有效地细化晶粒组织.     

高能球磨法制备Ag-Cr触头合金

采用机械合金化方法制备Ag-Cr合金,研究不同球磨时间对粉末晶体结构、晶粒尺寸、微观应变和表面形貌的影响,不同转速、相同球磨时间对粉末结构的影响以及合金密度、硬度随烧结温度的变化。结果表明:当机械球磨给予合金粉末足够的能量,就能够让铬固溶在银中形成过饱和固溶体;随着高能球磨时间的延长,晶粒逐渐细化、微观应变量逐渐变大,球磨65h时,平均晶粒尺寸为18.40nm,微观应变量为0.14%。烧结温度为850℃时,合金维氏硬度值约达99,密度达9.35g/cm3。     

球磨时间对镍基ODS合金拉伸性能的影响

研究了球磨时间对Y2O3氧化物弥散强化(ODS)镍基高温合金机械合金化和拉伸性能的影响.镍基高温合金采用机械合金化和热压烧结方法制备.镍基ODS高温合金粉末是在行星式球磨机上进行球磨.采用扫描电镜及X射线衍射分析了球磨时间对镍基ODS合金粉末形貌和物相的影响.研究结果表明,Y2O3氧化物弥散强化镍基高温合金机械合金化粉末尺寸随研磨时间的增加先增大后减小,8h粉末颗粒尺寸达到最大,之后粉末颗粒尺寸逐渐减小,28h后,镍基ODS合金粉末尺寸稳定且均匀.拉伸结果表明,采用研磨28h的合金粉末制备的镍基ODS合金具有最高的抗拉强度(1300MPa).     

过共析Ti-Cr合金的机械合金化

以钛，铬元素粉为原料，在行星式球磨机上采用φ20mm的淬火钢球，以200r/min的球磨速度和15：1的球料比，研究了Ti-20%Cr(ω(B)和Ti-30%Cr(ω(B)两种合金的机械合金化（MA）规律，研究结果表明；在球磨初期的2h内钛的（011）主衍射峰强度迅速降低，（010）第二衍射峰强度提高并成为最强峰，同时铬的衍射峰强度提高；随着球磨时间的增加，钛和铬的X射线衍射峰均发生宽化，强度下降和衍射角左移并减小；当球磨时间为30-40h时，钛逐步非晶化，但在本试验条件下铬没有发生非晶化；MA的前10h是粉末晶粒细化，晶格应变和合金化进行的最迅速的时期，经该阶段球磨后铬的晶粒尺寸可以达到20nm，进一步示磨有利于获得过饱和固溶的合金粉末；两种合金在超过100h的MA过程中均未发现在固相合成Laves相TiCr2；确定30-40h为制备纳米晶或非晶过饱固溶Ti-Cr合金粉末的合理球磨时间。     

高能球磨法制备Fe_3Si合金粉末

采用高能球磨法研究了原子配比Fe75Si25的混合粉末在不同的球磨条件下的机械合金化,用X射线衍射(XRD)仪、扫描电子显微镜(SEM)表征样品的物相、晶体结构、晶粒尺寸和点阵常数,分析了Fe75Si25粉末的机械合金化机理。研究表明,球磨时间、球料比和球磨机转速对机械合金化(MA)进程有重要影响。MA 55h后可达到完全合金化,Si溶入Fe中形成α-Fe(Si)饱和固溶体,晶粒尺寸减小至7～8nm。     

机械合金化制备纳米级超细晶不锈钢的研究

用机械合金化的方法制备了纳米级超细晶不锈钢粉末,用X射线衍射仪及扫描电镜技术研究了机械合金化过程中粉末颗粒尺寸及晶粒度的变化.结果表明,随着球磨时间的延长,粉末颗粒的尺寸先略微增大,而后一直减小到约几个微米后保持不变;而粉末的晶粒一直减小,球磨时间达到1 844min左右就达到纳米级.     

冷喷涂制备cBN-NiCrAl金属陶瓷涂层EI北大核心

采用机械合金化制备40vol%cBN-NiCrAl金属陶瓷复合结构粉末,采用冷喷涂制备了40%cBN-NiCrAl(体积分数)金属陶瓷复合结构涂层。研究了机械合金化过程对粉末的相组成、晶粒尺寸以及显微组织的影响。采用扫描电子显微镜和X射线衍射分别表征不同球磨时间下粉末以及冷喷涂涂层的显微组织和相结构。采用Scherrer公式估算不同球磨时间下粉末以及冷喷涂涂层中合金基体相的晶粒尺寸。结果表明,40vol%cBN-NiCrAl金属陶瓷粉末球磨40h后,基体的平均晶粒尺寸达到~50nm;复合结构涂层组织致密,硬质颗粒在合金基体中分布均匀。喷涂过程中,粉末相结构未发生变化,晶粒尺寸也未发生明显的长大。测试表明涂层的显微硬度约为1170HV0.3。     

Mo-Cu高能球磨过程实验研究及固溶度数值模拟

采用高能球磨方法对Mo-3%(质量分数)Cu、Mo-10%(质量分数)Cu复合粉末进行机械合金化加工,球磨时间为0～50h。通过扫描电镜及X射线衍射等对复合粉末的形貌、X射线衍射特征进行了分析,并对Cu在Mo中的固溶度用热力学方法进行了研究。结果表明,通过机械合金化方法可以得到超细小且均匀的纳米晶复合粉末,平均晶粒尺寸在60nm左右;从热力学平衡角度出发,通过细化晶粒来提高Cu在Mo中的固溶度极限可以用数值模拟来表达。     

机械合金化Fe50Ti50非晶的形成及球磨强度对它的影响

本文通过电子扫描和Ｘ衍射对机械合金人Ｆｅ５０Ｔｉ５０非晶粉末形成做了研究。研究发现：机械合金非晶形成可以大致地分为二个阶段－粉末的破碎阶段和非晶的形成阶段。另外，对球磨强度对非晶形成的影响进行了研究。结果表明：强度低时粉末需要较长的时间才能形成非晶，强度高时粉末形成非晶的时间大大缩短，但在随后的球磨中，粉末会重新晶化形成新相。     

晶态 Ni 粉与非晶 Fe_(78)Si_(12)B_(10)球磨时的固态反应

研究了晶态 Ni 粉与非晶 Fe_(78)Si_(12)B_(10)球磨时的固态反应。结果表明,当以(?)17at.-%Ni 和30at.-%Ni 与相应的非晶粉混合球磨后,产物为新的含 Ni 的完全非晶粉末。当以50at.-%Ni 与相应的非晶粉末混合球磨后,除了生成新的非晶相外,还有γ(Fe,Ni)相生成。     

Optical properties of Bi12SiO20 (BSO) and Bi12TiO20 (BTO) obtained by mechanical alloying

Mechanical alloying has been used successfully to produce nanocrystalline powders of BTO and BSO. The milled BTO and BSO were studied by x-ray powder diffraction, DTA, infrared and Raman scattering spectroscopy. After 7 hours of milling the formation of BTO and BSO was confirmed by x-ray powder diffraction. The infrared and Raman scattering spectroscopy results suggest that the increase of the milling time lead to the formation of ferroelectric BTO and BSO, as seen by x-ray diffraction analysis. These materials are attractive for various electro-optical devices, including optical data processing. They present a number of attractive features as reversible recording materials for real-time holography and image processing applications. This milling process presents the advantage, that melting is not necessary, and the powder obtained is nanocrystalline with extraordinary mechanical properties. The material, can be compacted and transformed in solid piezoelectric ceramic samples. The high efficiency of the process, opens a way to produce commercial amount of nanocrystalline piezoelectric powders. Due to the nanocrystalline character of this powder, their mechanical properties have changed and for this reason a pressure of 1 GPa is enough to shape the sample into any geometry.     

高能球磨Nd_(14)Dy_1Fe_(72)Co_5B_8合金的微观结构和磁性

本文采用 X 射线衍射,透射电镜和振动样品磁强计等技术研究了 Nd_(14)Dy_1Fe_(72)Co_5B_8合金在高能球磨过程中的结构变化以及结构与矫顽力的关系。我们认为高能球磨 Nd_(14)Dy_1Fe_(72)Co_5B_8合金的矫顽力源于晶界对畴壁的钉扎。在球磨初期,矫顽力随球磨时间的增加而增加,这主要归结于晶粒细化引起的晶界密度的增加。当球磨时间超过30小时,矫顽力随球磨时间的增加而减小,这可能是由于在球磨过程中引入很大的微观应力和高密度的缺陷,导致 R_2TM_(14)B(R=Nd、Dy;TM=Fe、Co)磁性相的磁晶各向异性场降低。     

Microstructural characterization of field assisted sintered bulk nanostructured V-4Cr-4Ti alloys

This article deals with synthesis of single-phase bulk nanostructured V-4Cr-4Ti alloy by mechanical alloying and field assisted sintering. Mechanically alloyed powders were sintered at 1050 and 1100°C with different sintering time. Both powder and sintered samples were subjected to structural and morphological characterization using x-ray diffraction and electron microscopy studies. x-ray diffraction and transmission electron microscopy studies of sintered samples confirm that field assisted sintering technique aids nanostructuring in V-4Cr-4Ti alloy. Microstructural parameters of sintered samples were calculated from x-ray diffraction patterns. Role of sintering variables on the microstrain evolution and subsequent domain size reduction in bulk V-4Cr-4Ti alloy are briefly discussed. Optimal sintering parameters to achieve nanostructured V-4Cr-4Ti alloy by field assisted sintering were deduced. Micro-hardness and relative density of sintered V-4Cr-4Ti alloy are found to increase with sintering temperature and sintering time.     

球磨条件对Ni－Ti粉末结构转变及机械合金化速度的影响

用ＸＲＤ分析研究了搅拌式球磨过程中球磨条件对Ｎｉ－Ｔｉ单质混合粉末结构演化的影响．定量测定了球磨粉末微观应变、微晶尺寸、镍的晶格常数及衍射峰相对微射强度与球磨转速及装球量的关系．研究了球磨功率对球磨温升、粉末微晶尺寸，层片状结构转变的影响，确定了非晶化所需时时间与工艺条件的关系，结果表明球磨功率成粉末塑性变形能增加，微晶尺寸减小．层片组织细化，同时微观应变大，晶格常数变化快，非晶化所需时间减小．     

Synthesis of Nanograined Ti-Al-Cr-Nb-X [X = Ni-P-Coated Graphite and Carbon] Intermetallic Matrix Composites by Mechanical Alloying

In the present work, TiAl-based intermetallic matrix composite with second phase reinforcement as Ni-P-coated carbon and graphite powders were synthesized by mechanical alloying route. Graphite powder (20–30 µm) and elemental carbon powders (1–5 µm) were coated with Ni-P by the electroless coating technique, which was added to the elemental powder mixtures of Ti-48Al-1%Cr -1%Nb with 1% composition of either of the two. The powder mixtures were subjected to mechanical alloying at 300 rpm up to 250 h using toluene as a process control agent. The samples were collected after 25 h duration and characterized. The formation of TiAl (γ) and Ti₃Al (α ₂) phases are confirmed by x-ray diffraction. The formations of these phases were found after milling for 75 h in case of graphite addition and 100 h in case of carbon addition in the intermetallic matrix. The mechanically alloyed samples milled for different extents of time were examined by a field emission scanning electron microscope (FESEM) and energy dispersive x-ray (EDAX) spectroscopy; the grain size was determined to be in the size range of 140–189 nm for the mechanically alloyed mixture.     

球磨条件对Ni—Ti粉末结构转变及机械合金化速度的影响

用ＸＲＤ分析研究了搅拌式球磨过程中球磨条件对Ｎｉ－Ｔｉ单质混合粉末结构演化的影响，定量测定了球磨粉末微观应变，微晶尺寸，镍的晶格常数及衍射相对微射强度与球磨转速及装球量的关系，研究了球磨功率对球磨温升，粉末微晶尺寸，层片状态结构转变的影响，确定了非晶化所需与工艺条件的关系，结果表明球磨功率或粉塑性变形能增加，微晶尺寸减小，层片组织细化，同时微观应变大，晶格常数变化快，非晶化所需时间减小。     

机械合金化制备FeSiAl合金粉末的研究

采用机械合金化的方法制备了FeSiAl合金粉末样品。以硅钢粉和铝粉为原料,按摩尔分数Fe3Si0.4Al0.6配比,研究其机械合金化过程,并对机械合金化的机制进行探讨。用激光粒度仪、X射线衍射(XRD)和扫描电子显微镜分析材料的粒度、形貌和结构。研究表明,Fe3Si0.4Al0.6混合粉末球磨30h后,粉末粒径可达18μm;Fe3Si0.4Al0.6混合粉末经高能球磨20h后,形成具有bcc结构的α固溶体;球磨继续进行,合金化的粉末和晶粒不断细化。     

Mechanical alloying of biocompatible Co–28Cr–6Mo alloy

We report on an alternative route for the synthesis of crystalline Co–28Cr–6Mo alloy, which could be used for surgical implants. Co, Cr and Mo elemental powders, mixed in an adequate weight relation according to ISO Standard 58342-4 (ISO, 1996), were used for the mechanical alloying (MA) of nano-structured Co-alloy. The process was carried out at room temperature in a shaker mixer mill using hardened steel balls and vials as milling media, with a 1:8 ball:powder weight ratio. Crystalline structure characterization of milled powders was carried out by X-ray diffraction in order to analyze the phase transformations as a function of milling time. The aim of this work was to evaluate the alloying mechanism involved in the mechanical alloying of Co–28Cr–6Mo alloy. The evolution of the phase transformations with milling time is reported for each mixture. Results showed that the resultant alloy is a Co-alpha solid solution, successfully obtained by mechanical alloying after a total of 10 h of milling time: first Cr and Mo are mechanically prealloyed for 7 h, and then Co is mixed in for 3 h. In addition, different methods of premixing were studied. The particle size of the powders is reduced with increasing milling time, reaching about 5 μm at 10 h; a longer time promotes the formation of aggregates. The morphology and crystal structure of milled powders as a function of milling time were analyzed by scanning electron microscopy and XR diffraction.