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     

Ni—Ti—Cu粉末的机械合金化

用ＴＥＭ研究了Ｎｉ４０Ｔｉ５０Ｃｕ１０粉末在球磨过程中，颗粒尺寸及微观结构的变化。球磨６０小时后，得到非晶相粉末。用ＸＲＤ研究了球磨工艺条件对衍射峰相对强度和晶格常数的影响，结果表明，提高球磨转速和球料比，加快颗粒细化和合金化过程，合金化过程中，Ｃｕ和Ｎｉ原子向Ｔｉ中扩散速率较快，这与Ｔｉ的原子半径较大有关。ＤＳＣ测定了晶化转变开始温度为５１１℃。     

Synthesis and Characterization of Nanocrystalline Ni-Ti and Ni-Cr Powders by Mechanical Alloying

Nanocrystalline powders in the Ni-Ti and Ni-Cr systems were prepared by mechanical alloying (MA) of elemental crystalline powders in an inert atmosphere. The microstructure of the mechanically alloyed powders were characterized by XRD and TEM. The ball-milling process results in a drastic decrease of the crystallite size to the nanometer scale. X-ray diffraction analysis reveals that in the Ni-Cr system, no diffraction peaks from NiCr compound were observed even after 20 h of ball milling; while the lattice parameter of Ni increased with the milling time. In the Ni-Ti system, amorphous alloy was formed. Crystalline intermetallic compounds were obtained by post heat treatment of the amorphous alloy.The crystallization temperature of the amorphous NiTi alloy was obtained be DSC measurement.     

Mechanical Alloying of Co and Al Powders

1.IntroductionMechanical alloying is one of the effec-tive methods to prepare amorphous alloys[1].This method was first used by Koch etal.to prepare the Ni_(60)Nb_(40)amorphous alloy[2].Since then many other amorphousbinary alloys have been prepared by the     

Synthesis of MoSi2 by Mechanical Alloying

The microstructure evolution of mechanical alloyed Mo-66.7%Si powder using the high-energy ball mill has been studied by X-ray diffraction and scanning electron microscopy. The results showed that MoSi2 can be synthesized by MA of Mo-66.7%Si powder mixtures. Cold welding behavior between Mo and Si powders plays an important role in the preparation of MoSi2 by the MA.     

Effect of Mechanical Alloying and Sintering on Ni-Ti Powders

Commercially pure nickel-titanium powders were mechanically milled in a vertical attritor mill under protective atmosphere for various times from 10 to 24 hr. Products were then compacted and sintered at different temperatures for different times. Amorphization and interatomic phase formation were determined by X-ray diffractometry, scanning electron microscopy, and differential scanning calorimetry. Porosity, virtual density, transition temperatures, and the amount of Ni₃Ti first increased and then decreased with the milling time. Presence of oxygen in the milling atmosphere showed partial crystallization of NiTi intermetallic compound accompanied by titanium oxide formation.     

机械合金化制备纳米Cu-Zn-Al2O3复合粉末的研究

采用X射线衍射仪、电子扫描电镜和透射电镜等研究了Ar气氛保护下Cu-Zn-Al2O3复合粉末在高能球磨过程中发生的机械合金化反应,分析了不同球磨时间对a-Cu(Zn)的晶格常数、晶粒尺寸以及复合粉末粉体形貌、颗粒尺寸的影响.结果表明,球磨初期,Cu的晶格常数增大,但75h后由于γ相的析出,a-Cu(Zn)晶格常数减小;高能球磨120h后,可获得氧化铝颗粒弥散分布的纳米级Cu(Zn)复合粉末.     

机械合金化法制备W—Cu合金的研究

采用高能球磨的机械合金化法制备W—Cu合金,对其在实验过程中的工艺条件进行了研究。结果表明：随着球磨时间的延长,粉末的粒度逐渐细化,比表面积逐渐增大。球磨过程分为三个阶段。最佳工艺条件是：当球料比为5：1,W：Cu为8：2,球磨时间达到30h时,铜粉和钨粉基本形成固溶体。球磨过程加入少量的无水乙醇,防止在球磨过程中粉末被氧化。     

Influence of Milling Conditions on the Mechanical Alloying of Fe-B Powders

1.IntroductionTheFe-Bamorphousalloyshavebeensynthesizedinawideconcentrationrangebymeltquenching[1ro2]orvacuumevaporation[3~5].Recently,someworkshowedthatamorphousalloysoftheFe-Bsys-temhadbeensuccessfullypreparedbymechani-calalloying[6~1o].Inthispaper3amorphousandnanocrystallineFe-Balloysmadebymechanicalal-loyingofelementalFeandamorphousBpowdersinawidecompositionrangearestudiedbyX-raydiffrac-tion,M6ssbauerspectroscopyandthermalanalysismeasurements.Especially,theeffectsofmillingcondi-tions,s…     

Formation Mechanism of NiAl/TiB_2 Nanocomposite by Mechanical Alloying Elemental Powders

A NiAl/TiB2 nanocomposite is synthesized by mechanical alloying elemental powders. Upon milling for a certain time, an abrupt exothermic reaction occurs and a large amount of NiAl and TiB2 compounds form simultaneously. It is suggested that two separate chemical reactions,i.e. Ni+Al →NiAl and Ti+2B→TiB2, are involved during the exothermic reaction. Additionof Ti and B to Ni-Al system impedes the structural evolution of Ni and Al powders and delays the abrupt reaction. The final products are equilibrium phases without any metastable phases formed. This type of reaction is suggested to be suitable for alloy systems with two large heatrelease reactions.     

Synthesis of Aluminium-Cementite Metal Matrix Composite by Mechanical Alloying

Cementite powder was prepared from elemental iron and graphite powder by mechanical alloying (MA) in a specially built dual-drive planetary mill. The phase evolution, particle-size distribution, and morphology of particles were studied during 40 hours grinding period. X-ray diffraction (XRD) shows formation of cementite and other iron carbides along with elemental iron after milling, whereas after annealing only cementite is present. Initially particle size increases with milling due to ductility of iron powder and then reduces with further milling.

Al-cementite composite was synthesized by mixing cementite with Al powders, and then by hot pressing or cold compaction and sintering. XRD analysis of Al-Fe₃C composite shows Fe₃C, FeAl, Al, and other iron carbides along with Al₄C₃ after sintering. Scanning electron microscope (SEM) micrograph of hot-pressed samples shows excellent compatibilility between Al matrix and cementite particles.     

机械合金化制备Ag-Cu-Sn钎料的组织和热稳定性

研究了机械合金化制备Ag-Cu-Sn三元体系形成过饱和固溶体的可能性,并对所得到的非平衡球磨产物的组织结构、热稳定性及其铺展重熔后的金相组织进行了表征。结果表明,通过控制球磨工艺和第三组元含量,可得到以过饱和固溶体为主要组成相的钎料合金粉,减少或细化脆性金属间化合物相。真空退火时,富银固溶体相较稳定,富铜固溶体相易于分解生成Cu_3Sn,银锡化合物可分解形成Ag基固溶体和富锡相,铜锡化合物的分解产物则为多种中间相,随退火温度的升高,转变顺序逐渐向铜锡原子比例增大的方向进行。以过饱和固溶体为主要组成相的钎料合金粉在重熔后虽然仍存在金属间化合物相,但金相组织明显细化。     

机械合金化法制备电动汽车电机用Fe-Si-Al合金粉

利用机械合金化法制备电动汽车电机用Fe-Si-Al合金磁粉;采用X射线衍射分析和扫描电子显微镜分别表征机械合金化过程中合金粉体的相结构和形貌,采用热分析对合金粉体的稳定性进行分析。结果表明:按照(FeSi)_(75)Al_(25)的原子比进行配料合金粉体,球磨10 h生成纳米晶α-Fe(Al,Si)固溶体,为体心立方晶体结构,粒径为1~20μm;球磨15 h,颗粒不断细化,晶粒粒径可达30 nm;(FeSi)_(75)Al_(25)磁粉在机械合金化过程中形成了具有典型层状结构且表面各种元素均匀分布的合金粉末包覆薄膜,无非晶相生成。     

机械合金化过程中粉末变形与形成复合粉的工艺条件

本文将镍与钛单质混合粉在搅拌式高能球磨机中球磨。采用电子探针研究了粉末组织随球磨时间的变化。测定了了片状粉末的厚度以及复合粉分数随球磨时间的变化，并根据粉变形模型研究了球磨时形成复合粉所需时间与工艺条件的关系。     

机械合金化制备的Fe1-xNix合金纳米晶粉末的形貌和微结构

利用机械合金化方法制备了Ｆｅ１－ｘＮｉｘ合金纳米晶粉末,Ｘ分别为０．１５、０．４５、０．８０,球磨时间为２、４、８、１６、４０ｈ。利用扫描电子显微交易和坶分析仪观察和分析了样品的形貌和微结构。发现整个球磨过程枳发为３个阶段。开始阶段,由于冷焊,Ｆｅ、Ｎｉ混合粉末凝聚成一些粒径较大的颗粒;在中间阶段,内应力达到最大值,原先形成的大颗粒破碎,粒径分布变窄;最后阶段,ＦｅＮｉ粉完全合金化,粒度再次增大,     

机械合金化Co-Zr非晶软磁合金粉末的形成及热稳定性分析

研究了Co-Zr二元相图上4个共晶点成分配方Co90Zr10、Co53Zr47、Co35Zr65和Co21Zr79在球磨条件下的非晶态合金形成能力。采用X射线衍射和差热分析(DTA)对粉末的结构及热稳定性进行了分析。XRD分析结果表明,4种配方在一定的球磨时间内都能形成非晶态合金,其中非晶形成能力最强的为Co35Zr65。DTA分析结果表明,该合金系具有较高的热稳定性,并具有较高的非晶形成能力。球磨时间对非晶的形成有重要影响,球磨时间过长,使形成的非晶态合金粉体反而向晶体转化。     

Mechanical Alloying of Ti50Al50 Powders and Their Consolidated Properties

Elemental powder mixtures of 50Ti-50Al (at.%) were mechanically alloyed via various ball milling methods. The microstructural evolution during the milling indicates that the mechanical alloying behavior is strongly affected by milling methods, and horizontal ball milling is most effective for producing homogeneous metastable powders. The mechanically alloyed powders were consolidated by vacuum hot pressing followed by homogeneous annealing. Compression testing results showed that the annealed specimens still retain fine grains and have a good combination of fracture strength and ductility, as compared to cast specimens of the same alloy.     

NiAl(Co)-TiC粉末的机械合金化原位制备纳米复合材料

用高能球磨机分别对四种成分的Ni50-Al50-x-Cox 10%(体积分数,下同)TiC (x=5,10,20)和Ni50-Al45-Co5 20%TiC粉末进行机械合金化,得到原位内生TiC弥散强化的NiAl(Co)纳米复合粉末.结果表明,球磨Ni50-Al45-Co5-10%TiC粉末过程中,爆炸反应机制生成NiAl(Co)和TiC化合物,其中NiAl(Co)化合物晶粒仅为10nm左右,TiC晶粒为35～50nm.但当TiC含量增加到20%时,其爆炸反应起始时间延后20min.同时随着Co含量增加,Ni50-Al40-Co10-10%TiC粉末的机械合金化的产物仍为NiAl(Co)和TiC,但NiAl(Co)化合物的生成机制转变为扩散反应机制.进一步增加Co含量(20%,原子分数)则导致了γ-Ni(Al,Co,Ti,C)过饱和固溶体的形成,反应机制仍为互扩散反应.