SPEX 8530 振动盘式研磨机

8000M机械合金自蔓延燃烧反应-都柏林三一学院(爱尔兰)

Mechanically-induced combustion reactions were carried out in a transparent quartz vial. The combustion processes were followed by high-speed video recording and optical pyrometers. Depending on the vial dynamics, the powder particles were seen to gather in a periodic collective motion, behaving like a granular gas characterised by subsequent changes in its density. After ignition, a considerable increase of brightness was observed, due to the extremely rapid propagation of the high-temperature reaction to the whole mass of powder. Experimental observations ?nd a very good correlation if compared to the results of numerical calculations simulating the particle system dynamics. Balls and powder dynamics were reproduced according to a well-known visco-elastic force scheme, while chemical conversion of each powder particle was described by a conventional nucleation-and-growth kinetics. The propagation mechanism of the reaction was studied and related to the dynamic features of the whole system.

Al2O3 -WC合成的高能球磨反应-圣保罗大学(巴西)

Like most carbide-based composites, the two main characteristics of alumina–tungsten carbide (Al2O3–WC) composites are high hardness and high wear resistance. These features confer the composites important engineering applications, in particular when they are used as cutting tools. The present research involved a study of Al2O3–WC nanometric powders obtained through reactive milling. In this process, high-energy milling promotes the reaction in a mixture of reactive powders. The material was milled in a high-energy SPEX 8000 Mixer/Mill, using WO3,Al and C precursor powders. The highly exothermic self-propagating high-temperature synthesis (SHS) type reaction was self-sustained, producing a temperature peak that was detected by a thermocouple attached to the external surface of the vessel. Using stoichiometric proportions of the reagents to reduce theWO3 and to obtainWC, and adding Al2O3 as diluent, the SHS reaction occurred up to a limit of 0.8mols of diluent, forming not only alumina but also aW2C mixture with littleWC. To obtain onlyWC it was required the addition of more than 0.8mols of C, which indicates that the reaction may have occurred through a gaseous phase reaction mechanism.

MgNi型储氢合金的机械合金化的电化学研究-华中科技大学(中国)

The electrochemical properties of amorphous MgNi-based hydrogen storage alloys synthesized by mechanical alloying MA were evaluated. The results show that these amorphous Mg Ni alloys exhibit a higher discharge capacity and relatively good rate capacity at 50 50 a suitable grinding time while their cycle life is very poor. In order to improve the cycle life, the surface of the amorphous Mg Ni 50 50 alloy was coated with Ti, Al and Zr in Spex 8000 millrmixer and the coating effects were further investigated. Based on experimental results, two kinds of MgNi-based amorphous alloys are designed by substituting part of Mg in MgNi-based alloys by suitable elements. These alloys are then composed of four components. Thus, the cycle life of electrodes consisting of these quaternary amorphous alloys is greatly improved. q2000 Elsevier Science S.A. All rights reserved.

Mg和Ni机械合金化过程中的显微组织演变-加州大学(美国)

This study investigates the microstructural evolution during mechanical alloying of Mg and Ni, and during subsequent heat treatments of SPEX milled powders. The milling was performed under an inert argon atmosphere, employing two different ball-to-powder ratios (BPR): 10:1 and 20:1. It was observed that a large number of defects were produced during the ?rst hours of milling. These defects led to the amorphi- zation of part of the system, and promoted an extensive re?nement of the microstructure as well. Later on, the formation of the Mg2Ni compound due to the crystallization of the amorphous phase was observed. The microstructural details showed us that a possible complete sequence of phase transformations during milling of pure Mg and Ni could be: Mgc +Nic →Mgnc +Nic →amorphous + Ninc +Mgnc →amorphous +Ninc +Mg2Ninc →Mg2Ninc, where c and nc stand for crystalline and nanocrystalline, respectively. On the other hand, subsequent heat treatments of the milled powder showed that the amorphous phase could also be transformed into Mg2Ni by heating. Finally, the knowledge of the evolution of the microstructure during milling and annealing were combined to propose an optimal processing route to ef?ciently obtain the Mg2Ni compound.

用机械合金化方法制备Ni-Al系金属间化合物

用球磨机分别对Ni-50at.-%Al和Ni-25at.-%Al混合粉末进行机械合金化，并对Ni3Al预合金粉末进行高能球磨，观察了粉末的金相组织，测定了粉末的硬度、平均直径和晶粒尺寸，并作了XRD物相分析。结果表明，经3h研磨，Ni-25at.-%Al混合粉末成为无序的亚稳定Ni固溶体，而Ni3Al预合金粉末由L12型长程有序金属间化合物转变为fcc无序固溶体；球磨更长时间，则形成纳米晶。