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Fe-Ni粉末的相结构

使用XRD和Moessbauer等方法，研究了在Ar气氛下机械合金化Fe—Ni粉末相结构的变化．结果表明，在机械合金化Fe64-Ni36粉末过程中，fcc相的数量随着球磨时间的增加先增加然后减少，与加乙醇球磨Fe64-Ni36的情形相同．当Ni的含量(原子分数)大于50％时，有fcc相、顺磁相和FeNi3形成，当Ni的含量低于50％时，bcc相的数量随着Ni含量减少而增加．Moessbauer谱的结果表明，因球磨时间或Fe、Ni比例的不同，Fe—Ni球磨粉末固溶体具有不同结构的原子配比。     

Cu-Cr机械合金化工艺研究进展

综述了机械合金化工艺制备Cu-Cr合金的研究进展。主要包括Cu-Cr机械合金化的基本原理;Cu-Cr粉末机械合金化过程的影响因素,包括球磨时间、球料比,填充率、球磨机转速、过程控制剂、球磨温度等;Cu-Cr合金机械合金化过程的缺陷。简要讨论了机械合金化方法生产Cu-Cr合金粉末的发展前景。     

机械合金化过程中六方相晶格畸变特点的研究

通过分析球磨试样和球磨后退火试样的Ｘ射线衍射谱，研究了Ｔｉ，Ａｌ混合粉末机械合金化过程中六方相α－Ｔｉ和Ｔｉ３Ａｌ的晶格畸变特点。结果表明，六方相畸变特点为晶体常数减小和ｃ，ａ轴比值ｃ／ａ减小，其中α－Ｔｉ的（０１１１）面和Ｔｉ３Ａｌ的（２０２１）面原子错排最为严。讨论了位错滑移系统和空穴的引入与晶格畸变特点的联系。     

高能球磨Si还原V2O5的固相反应

采用机械还原的方法以Si／V2O5为原料直接制VO2／SiO2复合陶瓷粉，主要探讨了高能球磨实现固相反应的动力学条件。利用X射线衍射仪和扫描电镜分析了不同球磨时间粉末的物相、形貌及结构变化，结果表明，球磨25hV2O5衍射峰消失，36h发生固相还原反应生成新相VO2。随着球磨的进行，V2O5的层状结构断裂，表面吸附小颗粒更均匀化，晶格常数发生明显改变，为室温下发生固相还原反应提供新增表面能、减小反应物之间的接触距离以及歧变能。     

机械合金化制备钼铜复合材料

通过扫描电镜、透射电镜及X射线衍射等对Mo-Cu复合粉末的粉末形貌、合金化程度及烧结后合金组织结构进行分析,研究了高能球磨对Mo-Cu假合金性能的影响.结果表明,采用高能球磨机械合金化和氢气气氛烧结的工艺,可以获得相对密度高达99%的Mo-Cu复合材料.     

机械合金化中的固态反应

机械合金化中的固态反应（机械化学反应）被广泛用于制备碳化物、金属间化合物、复合材料、纳米微粒、机械化学反应是一种常温下进行的远离平衡态的固态反应,反应的生成物以丰核－－逐渐长大模式生成或经自维持反应形成。     

机械合金化过程理论模型研究进展

对机械合金化过程理论模型主要模拟方法与结合作了评述。机械合金化过程理论模型大致可分为四类，运动学模型，碰撞模型，能量传输模型与球磨图，温升效应模型，这些模型可在一定范围内预测工艺参数和粉末材料参数对机械合金化过程和结果的影响，有利于机械合金化工艺的优化。     

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。     

机械合金化制备形状记忆合金的研究

机械合金化技术(MA)是一种制备材料的新工艺,用它可以制备性能优越的形状记忆合金.综述了机械合金化技术在TiNi、Cu-Al-Ni、Cu-Zn-Al、Cu-Al-Nb等形状记忆合金制备上的研究状况.     

基于外场辅助的机械合金化研究

机械合金化（MA）技术作为一种制备纳米材料的有效方法已获得广泛的应用。把机械合金化过程中的磨球机械能与其它物理能有机地结合起来,能够增强对粉末的作用,有效提高机械合金化效率。本文简单回顾了机械合金化的发展,对外加物理场辅助作用下的几种高能球磨工艺进行了详细分析。采用物理能辅助机械球磨,从而使粉末得到复合作用或活性激活,是机械合金化效率提高的原因。     

机械合金化W-Cu固溶体的形成机理

采用W-15%Cu和W-25%Cu两种复合粉,开展了机械合金化诱导W-Cu固溶度扩展机制的研究.研究表明:两种粉末经8 h高能球磨后,Cu固溶入W中形成固溶体.机械合金化诱导W-Cu固溶度扩展的主要机制,一方面是高能球磨过程中所引起的粒子纳米化,形成大量的纳米界面,许多原子"储存"在这些纳米晶界上,诱导W-Cu固溶浓度扩展.另一方面是机械合金化过程晶格严重畸变,晶粒内部生成高密度缺陷,成为溶质快速扩散的网络通道,诱导过饱和固溶体的形成.     

Alloying behaviour in nanocrystalline materials during mechanical alloying

The alloying behaviour in a number of systems such as Cu-Ni, Cu-Zn, Cu-Al, Ni-Al, Nb-Al has been studied to understand the mechanism as well as the kinetics of alloying during mechanical alloying (MA). The results show that nanocrystallization is a prerequisite for alloying in all the systems during MA. The mechanism of alloying appears to be a strong function of the enthalpy of formation of the phase and the energy of ordering in case of intermetallic compounds. Solid solutions (Cu-Ni), intermetallic compounds with low ordering energies (such as Ni₃Al which forms in a disordered state during MA) and compounds with low enthalpy of formation (Cu-Zn, Al₃Nb) form by continuous diffusive mixing. Compounds with high enthalpy of formation and high ordering energies form by a new mechanism christened as discontinuous additive mixing. When the intermetallic gets disordered, its formation mechanism changes from discontinuous additive mixing to continuous diffusive one. A rigorous mathematical model, based on iso-concentration contour migration method, has been developed to predict the kinetics of diffusive intermixing in binary systems during MA. Based on the results of Cu-Ni, Cu-Zn and Cu-Al systems, an effective temperature (T _eff) has been proposed that can simulate the observed alloying kinetics. TheT _eff for the systems studied is found to lie between 0·42–0·52T ₁.     

高温固相法制备锆英石工艺研究

为研究高温固相法制备锆英石的最佳工艺条件,以不同粒度的SiO2和ZrO2粉体为原料,在1 500℃条件下通过不同的保温时间进行锆英石的制备。利用激光粒度分析、X射线衍射、扫描电镜等手段对原料的粒度、物相与结构和微观结构进行表征。结果表明:不同粒度的SiO2和ZrO2粉体在1 500℃条件下通过保温1.5、3、4.5、6 h均可制备出锆英石,但d50=2.125μm的原料通过保温4.5、6 h所制备出的样品效果最好。利用高温固相法进行锆英石的工业化生产,原料的d50控制在2μm左右,在1 500℃条件下保温4.5 h的生产工艺比较合适,所制备样品的晶粒度主要集中在0.2~1.5μm之间。     

Solid state amorphization of Mg-Zn-Ca system via mechanical alloying and characterization

Magnesium based bulk metallic glasses have attracted significant attention of researchers due to better mechanical and corrosion properties when compared to their crystalline counterparts especially for biomedical applications. Scaling up the part size and production volumes of such materials through liquid metallurgy route is challenging. In this work amorphous Ca₅Mg_60+xZn_35?x (X = 0, 3 and 7) alloys have been successfully synthesized through solid state amorphization using a high energy planetary ball mill. X-ray diffraction was used to identify the crystalline phases of the powder during reaction. Evolution of amorphous phase was analysed using a parameter involving the ratio of integral area of peaks to the integral area of background (I_PB) obtained from XRD patterns. Results showed reaction time increases with decreasing Zn content in Ca₅Mg_60+xZn_35?x (X = 0, 3 and 7) alloy to obtain maximum amorphous structure with a small amount of residual crystalline phase. Prolonged milling of these powders, to eliminate residual crystalline phases, resulted in the nucleation of Mg_102.08Zn_39.6 phase. The composition dependent characteristic temperatures and thermal stabilities were studied using differential scanning calorimetry.     

Phase transformations and microstructural evolution of nanocrystalline Ti-18Zr-5Nb-3Sn-4Ta powders through mechanical alloying

ABSTRACT

The aims of the present study are to determine the possibility of obtaining a new, nanocrystalline Ti-18Zr-5Nb-3Sn-4Ta at.-% alloy by a ball milling method, and to observe the influence of various milling times on phase composition and structure of the obtained material. The X-ray diffraction results confirmed the alloy synthesis and revealed the presence of α- and β-Ti phases. The Rietveld refinement showed that the production method and the atomic radii of the elements used in the mechanical synthesis have influence on the structure. Scanning electron microscopy observation leads to the conclusion that the powder particles and the degree of aggregation change with increasing milling time.

This paper is part of a Thematic Issue on The Crystallographic Aspects of Metallic Alloys.     

Synthesis of nanocrystalline NiAl over a wide composition range by mechanical alloying

The paper reports the synthesis of nanocrystalline NiAl by mechanical alloying of pure metal mixture and a mixture of prealloyed powder with Ni/Al. A large number of compositions have been studied to establish the phase field of NiAl in the milled state. The phase field of NiAl in the ball milled condition was found to be much wider (10–68 at.% Ni) than its equilibrium phase field (45–59 at.% Ni). The metastable equilibrium achieved by mechanical alloying was identical for a given composition irrespective of the starting ingredients. The crystallite size of NiAl reached a minimum (5 nm) at the phase boundary of NiAl/Ni₃Al.     

机械合金化制备Nd60 Fe20 Al10 Co10非晶粉末的研究

利用机械合金化制备Nd60Fe20Al10Co10非晶粉末，采用X射线衍射(XRD)和振动样品磁强计(VSM)研究Nd60Fe20Al10Co10非晶的形成过程、磁性能变化及其与成分结构的关系。结果表明，90min后Al原子溶入Nd原子形成固溶体。球磨2h后出现少量非晶，20h后Co单质和Nd单质消失．组织为非晶相(含少量的α-Fe)。球磨100h最终得到非晶 少量的α-Fe纳米晶。球磨过程中，矫顽力随着合金中非晶的量增加而升高．球磨20h矫顽力达到43kA／m。Nd60Fe20Al10Co10合金具有硬磁性是由于非晶相的存在而造成的。     

机械合金化制备SbSn金属间化合物的研究

用机械合金化法制备SbSn金属间化合物.使用X射线衍射仪、扫描电子显微镜、透射电镜和DSC差热分析方法对Sb、Sn混合粉末经不同工艺条件合成的产物进行了分析.结果表明:机械合金化法可合成Sb-Sn金属间化合物;随着机械合金化持续进行,合金化的粉末和晶粒不断细化,晶粒内部产生很大的晶格畸变,并且球磨产生的密度和缺陷使原子扩散加快.     

球磨合成Fe3Al金属间化合物及其固相反应机理

Fe3Al金属间化合物是一种新型耐高温材料,并因其电热和磁性能受到重视。本文研究由铁、铝元素混合粉末利用高能球磨工艺合成Fe3Al。通过对冷焊现象的分析,用适量的有机物有效地控制了机械合金化过程。利用X射线衍射研究了反应物在球磨过程中的结构演变。通过对Fe／Al固相反应热力学的分析,认为Fe／Al原子比相等成分附近,固相反应最容易进行。