固液反应球磨工艺

介绍了一种固液反应球磨专利技术,即在一定温度区间,磨球介质直接对熔融金属或合金进行球磨,磨球直接和金属液体反应生成固相的金属间化合物粉末.综合报导了采用Fe、Cu、Ni、Ti等材质的磨球对熔融Sn、Sb、Zn、Al金属及其合金进行固液反应球磨的结果.研究了固液反应球磨工艺,并探讨了固液反应球磨的机理.     

机械球磨对Ti-Al复合粉扩散反应的影响

研究了粉末烧结制取Ti-Al金属间化合物过程中,机械球磨对Ti、Al混合粉扩散反应的影响.结果表明,机械球磨使Ti、Al混合粉形成具有层片结构的复合粉,且球磨时间越长,层片越薄越均匀.在固相下对不同球磨时间的Ti、Al混合粉压坯试样进行烧结后,通过X射线衍射、扫描电镜及能谱分析,结果表明,球磨时间越长,越有利于Ti、Al之间的扩散反应,越容易形成Ti-Al金属间化合物,并有利于组织的均匀化.     

机械球磨Ｔi—Al复合粉扩散反应的影响

研究了粉末烧结制取Ｔi-Al金属间化合物过程中,机械球磨对Ti,Al混合粉扩散反应的影响,结果表明,机械球磨使Ｔi,Al混合粉形成具有层片结构的复合粉,且球磨时间越长,层片越薄越均匀,在固相下对不同球磨时间的Ｔi,Al混合粉压坯试样进行烧结后,通过Ｘ射线衍射,扫描电镜及能谱分析,结果表明,球磨时间越长,越有利于Ｔi,Al之间的扩散反应,越容易形成Ｔi-Al金属间化合物,并有利于组织的均匀化。     

机械合金化的机制

机械合金化是一种制备平衡态和亚稳态材料的新兴技术。机械合金化的热力学与动力学不同于常规的固态反应，而且相转变方式与合金系统及球磨条件密切相关。着重评述了机械合金化过程中非晶态，金属间化合物，过饱和固溶体及纳米晶形成的特点及机制。     

高能球磨法制备纳米材料

本文系统地综述了用高能球磨法制备纳米晶材料的国内外现状。通过微观结构和性能方面的比较,发现用机械球磨方法制备的纳米晶与原子沉积法获得的材料具有相似的结构和性质。该方法工艺简单,近年来已成为制备纳米材料的一条重要途径。如可用于制备纳米结构的纯金属,金属间化合物,不互溶体系合金,氧化物弥散强化金属复合材料等。     

机械球磨对Ti/Al混合粉末组织和热稳定性影响的研究

为了探索一种制备高综合性能TiAl基金属间化合物的新方法，研究了机械球磨对Ti、Al粉末微观组织及其热稳定性的影响，结果表明，在机械球磨的作用下Al粉末晶粒以高于Ti的速率细化，最终形成局部含少量Ti 纳米晶的非晶，但在整个过程中未发现Ti、Al元素相互扩散形成Ti-Al金属间化合物中间相；不同球磨时间作用下的Ti/Al粉末中贮有不同的能量，且随时间的延长而增加，以非晶化粉末最为显著，内能的增加是由于机械合金化过程引入了大量的微观缺陷所致，对不同球磨时间的粉末进行热处理显示，球磨时间的增加可大幅度降低形成Ti-Al金属间化合物的温度，球磨75h的复合粉末甚至在350℃，保温1h即可转变成金属间化合物。     

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。     

机械球磨过程控制技术的研究进展

如何实现对机械球磨过程的控制，扬长避短，加快应用进程是当前发展机械球磨技术的研究热点之一。评述了机械球磨过程控制技术的研究进展，介绍了控制气-固反应的反应球磨技术，控制球磨中焊合-碎裂等基本过程的过程控制剂技术，及其在纳米粉体、氢化物、氮化物及复合材料等制备中的应用。     

机械合金化法合成金属间化合物NiAl粉末

由于NiAl基金属间化合物的一些优异性能,长期以来作为高温结构的候选材料而得到了广泛的关注。本文中用机械合金化法合成了NiAl金属间化合物粉末,详细介绍了球磨工艺,对NiAl金属间化合物粉末的形貌和物相进行表征。结果表明,金属Ni和Al的粉末在球磨机内仅球磨5h就可以使大部分金属粉末转化为NiAl金属间化合物,随着球磨时间的延长,金属间化合物有细化的趋势。     

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.     

Producing ternary intermetallic compounds powders by solid–liquid reaction ball milling

A novel mechanochemistry approach, defined as solid–liquid reaction ball milling, was applied to obtain single-phase Al–Cu–X (X = Fe, Co, and Ni) ternary intermetallic compound powders by reactions between milling medium (ball and cylinder) and liquid-state metals in certain temperature range, where the milling mediums made of metals with high-melting point and took part in the reaction as the solid-state reactants. Compared with the conventional mechanical milling technique, nanometer-sized intermetallic compound powders and some single-phase ternary intermetallic phases could be obtained at lower temperatures by the solid-state reaction ball milling. Furthermore, the reaction mechanisms of this mechanochemical approach have been discussed in details.     

Mechanochemically prepared reactive and energetic materials: a review

Reactive and energetic materials are typically metastable and are expected to transform into thermodynamically favorable reaction products with substantial energy release. Preparation of such materials by mechanical milling is challenging: They are easily initiated by impact or friction. At the same time, milling offers a simple, scalable, and controllable technology capable of mixing reactive components on the nanoscale. In most cases, for reactive materials milling should be interrupted or arrested to preserve the metastable phases. Arrested reactive milling was exploited to prepare many inorganic reactive materials, including nanocomposite thermite, metal–metalloid, and intermetallic systems. Prepared materials are fully dense composites with unique properties, combining high density with extremely high reactivity. Different milling devices were used to prepare reactive materials and an approach was developed to transfer the process conditions between different mills. Different milling protocols, such as milling at cryogenic temperatures or staged milling can be used to prepare hybrid reactive materials with different components mixed on different scales; it was also used to tune the particle size distributions of metal-based reactive material powders. Metal–halogen composites were prepared, with metal matrix stabilizing a halogen (e.g., iodine) at temperatures substantially exceeding its boiling point. Mechanochemically prepared reactive materials can be classified based on the energy of reaction between components and the energy of oxidation of the bulk material composition. Work on mechanochemical preparation of reactive and energetic materials is reviewed with the focus on unique properties and ignition and combustion mechanisms of the mechanochemically prepared reactive materials. An ignition mechanism for nanothermites involving preignition reaction leading to a gas release preceding rapid temperature rise is discussed. A combustion mechanism is also discussed, in which the nanostructure of the mechanochemically prepared material is preserved despite the very high combustion temperatures.     

Formation of B2 intermetallic NiAl and FeAl by mechanical alloying

Nanostructud B2 intermetallic compounds NiAl and FeAl have been prepared by mechanical alloying (MA) the elemental powder mixtures and subsequent heating. The structural evolution during MA was monitored by in situ thermal analysis and X-ray diffraction (XRD). The final products were characterized by transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). The results show that the nanocrystalline intermetallic compound NiAl, which is difficult to disorder by milling, was synthesized directly after an exothermic explosive reaction; whereas FeAl compound was formed after a thermal process of asmilled Fe(Al) solid solution obtained through interdiffusion during MA. The large heat of formation of NiAl compound is the main driving force for the exothermic explosive reaction, and the difference in diffusivity between NiAl system and FeAl system is suggested to be the main cause of the different behaviors of formation between NiAl and FeAl compounds by MA.     

Hydrogenation of the intermetallic compound Zr2Ni

We have determined conditions for the preparation of hydride phases with the composition Zr₂NiH_～5 by reacting the intermetallic compound Zr₂Ni with hydrogen or ammonia and identified the products of the reaction between the intermetallic compound and ammonia in the temperature range 150–500°C in the presence of NH₄Cl as an activator. The results demonstrate that the use of ammonia at 500°C leads to decomposition of the intermetallic compound and formation of zirconium hydride, zirconium nitride, and metallic nickel.     

Mechanochemical methods for the synthesis of new magnesium-based composite materials for hydrogen accumulation

We present a brief overview of works on the synthesis of magnesium hydrides and alloys by traditional methods and analyze mechanical methods for synthesis of these materials. Advantages of reactive milling for the preparation of new efficient hydrogen sorbents based on magnesium are discussed. It is shown that the reaction rate of the mechanochemical synthesis of MgH₂ increases four times as a result of the introduction of additives of intermetallic compounds based on Ti and Zr.     

Ni50Ti50非晶粉末在球磨时的稳定性

将Ｎｉ５０Ｔｉ５０单质混合粉末经机械合金化形成非晶态合，再进一步球磨使其产生晶化。结果表明，晶化产物为Ｎｉ３Ｔｉ金属间化合物。当Ｎｉ５０Ｔｉ５０非晶体加热时，产生的晶化产物有ＮｉＴｉ，ＮｉＴｉ２和Ｎｉ３Ｔｉ三种金属间化合物。本文通过ＤＳＣ差热分析，测定了Ｎｉ５０Ｔｉ５０非晶合金的晶化热及晶化激活能，并讨论了过度球磨时非晶晶化机制。     

Microstructural Evaluation of NiTi-powder,Steatite, and Steel Balls After Different Milling Conditions

The present research deals with the investigation of morphological characteristics after mechanical alloying of Ni–50 at. %Ti in a high-energy planetary ball mill at various milling times (i.e., 4, 8, 30, 40, 50, and 60 h). Crystallite size was observed to be decreased with the increase of milling time, entire titanium fused in the nickel trellis, and results of intermetallic NiTi. The shape of particle also changed from lamella to globular. Steatite-ceramic and hardened balls were separately used for the ball milling. The observations of morphologies revealed that steatite balls are more durable and wear resistant as compared to steel ball. This research shows that ball milling with steatite-ceramic balls is a cost-effective, high purity, and productive step toward the formation of NiTi intermetallic compound with homogeneous composition and desired particle size.     

Thermodynamic aspects of nanostructured Ti5Si3 formation during mechanical alloying and its characterization

Mechanical alloying (MA) was used to produce Ti₅Si₃ intermetallic compound with nanocrystalline structure from elemental powders. The structural changes and characterization of powder particles during milling were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), particle size analyser (PSA) and microhardness measurements. MA resulted in gradual formation of disordered Ti₅Si₃ intermetallic compound with crystallite size of about 15 nm after 45 h of milling. Also a thermodynamic analysis of the process was carried out using Miedema model. The results showed that in the nominal composition of Ti₅Si₃ intermetallic phase (X _Si ?=?0·375), formation of an intermetallic compound has the lowest Gibbs free energy rather than solid solution or amorphous phases. So the MA product is the most stable phase in nominal composition of Ti₅Si₃. This intermetallic compound exhibits high microhardness value of about 1235 HV.     

Supersaturated solid solutions and metastable phases formation through different stages of mechanical alloying of FeTi

Elemental equiatomic Fe-Ti powder mixture was mechanically alloyed in high energy ball mill. XRD, DTA and Mössbauer spectroscopy (at liquid nitrogen temperature) were utilized to monitor the kinetics as well as the accompanied structural and phase transformations through different stages of milling. Our experiments showed that formation of nanocrystalline FeTi compound proceeds via the formation of the supersaturated solid solutions β-Ti(Fe) and α-Fe(Ti) at the interface. After 36 hours of milling, the main part of powder mixture transformed not only to FeTi but also to Fe2Ti intermetallic compound. The transition of last part of super saturated solid solutions β-Ti(Fe) to those intermetallic phases was observed after annealing of this sample at 600 °C.