共查询到19条相似文献,搜索用时 203 毫秒
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对机械合金化制备的Mg2Ni纳米材料进行了循环伏安测试,获得了样品随扫描速度和温度变化的循环伏安曲线。测试结果表明:氧化峰的电位随扫描速度的加快有所正移;机械合金化制备的样品在室温下的吸氢性能显著增强,吸放氢速度随温度的升高而加快。X射线小角散射结果表明高能球磨制备的Mg2Ni粉末具有1-5nm以及5-10nm范围内的粒度分布,较小的粒度使得吸/放氢反应的活性位置增多和放氢的扩散路径降低,这可能是机械合金化制备的Mg2Ni纳米材料贮氢性能显著提高的原因。 相似文献
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利用高能球磨方法制备纳米Mg2Ni储氢合金,用于高容量MH/Ni电池氢化物电极电化学性能研究。XRD和TEM测试结果表明,机械合金化方法制备Mg2Ni合金的历程为合金化——非晶化——纳米晶化,球磨时间直接影响Mg2Ni合金的结构。高能球磨20h可以制备非晶态Mg2Ni合金,比普通的机械合金化方法制备非晶态Mg2Ni合金的时间减少了约5倍之多;高能球磨30h可以制备纳米晶态Mg2Ni合金,粒径在10nm以下,有团聚现象。研究了Mg2Ni纳米氢化物电极在不同温度下的电化学性能,并从热力学角度就Mg2Ni纳米氢化物电极的某些高温电化学性能进行了解释和推测。实验结果表明:在30~70℃范围内,随着温度增加,氢化物电极的电化学容量逐渐增加,在70℃时电化学容量可达530.5mAh/g,约为30℃放电容量273.2mAh/g的2倍,Mg2Ni纳米氢化物电极具有较好的高倍率放电性能及大电流充放电性能,这表明机械合金化方法制备的Mg2Ni纳米氢化物电极具备电动车用大型MH/Ni电池负极材料的初步条件,但容量衰减严重。 相似文献
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纳米晶粉末Mn70Bi30的机械合金化合成 总被引:3,自引:0,他引:3
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 相似文献
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采用电弧熔炼和机械合金化,随后在750℃,58MPa下热压制备了晶粒尺寸差别较大的Cu40Ni40Cr20合金,用X射线衍射仪、扫描电镜等分析手段对比研究了显微组织结构.结果表明:电弧熔炼制备的晶粒尺寸较大的Cu40Ni40Cr20合金为二相,组织极其不均匀;采用机械合金化,通过控制热压条件制备的纳米晶Cu40Ni40Cr20合金仍为双相,但显微组织均匀,稳定.随着球磨时间的延长,由于晶粒细化和应变的结果,衍射峰偏移并有明显的宽化产生,Cu在Cr或Cr在Cu中的固溶度明显增加,当球磨60h后,合金已由双相变成亚稳态的单相.由于机械合金化的粉末处于非平衡态,其超固溶度溶质随热压和真空退火过程的进行会慢慢脱溶分解出来,合金已由单相变为两相,两相颗粒均成倍长大,但仍然保持纳米级尺度;机械合金化、热压和退火后样品中Cu,Ni和Cr的晶格均未发生崎变;讨论了晶粒细化对合金显微组织的影响. 相似文献
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球磨条件对Fe-Ni纳米晶结构和磁性的影响 总被引:7,自引:0,他引:7
用机械合金化方法制备两组Fe100-xNix系纳米晶合金。采用不同的球磨条件:A组样品的球粉质量比为20:1,球磨机的转速为200r/min,对应着较高的球磨能量。B组样品的球粉质量比为14:1,球磨机的转速为160r/min。对应着较低的球磨能量。在相同的球磨时间(60h),不同的球磨能量下得到Fe-Ni系纳米晶合金的不同结构与磁性。前者基本上为单相Ni(FCC)的无序Fe-Ni固溶体而后者为α-Fe(BCC)与γ-Ni(FCC)混相合金。前者基本呈现超顺磁性的磁滞回线而后者却出现了Perminvar效应,吴峰腰形磁滞回线。本文对这些结果进行了讨论。 相似文献
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Synthesis of (Ni, Fe)3Al intermetallic compound by mechanical alloying (MA) of Ni, Fe and Al elemental powder mixtures with composition Ni50Fe25Al25 was successfully investigated. The effects of Fe-substitution in Ni3Al alloy on mechanical alloying process and on the final products were investigated. The structural changes of powder particles during mechanical alloying were studied by X-ray diffractometry, scanning electron microscopy and microhardness measurements. At the early stages, mechanical alloying resulted in a Ni (Al, Fe) solid solution with a layered nanocrystalline structure consisting of cold welded Ni, Al and Fe layers. By continued milling, this structure transformed to the disordered (Ni, Fe)3Al intermetallic compound which increased the degree of L12 ordering upon heating. In comparison to Ni–Al system, Ni (Al, Fe) solid solution formed at longer milling times. Meanwhile, the substitution of Fe in Ni3Al alloy delayed the formation of Ni (Al, Fe) solid solution and (Ni, Fe)3Al intermetallic compound. The microhardness for (Ni, Fe)3Al phase produced after 80 h milling was measured to be about 1170HV which is due to formation of nanocrystalline (Ni, Fe)3Al intermetallic compound. 相似文献
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C. E. Wen K. Kobayashi A. Sugiyama T. Nishio A. Matsumoto 《Journal of Materials Science》2000,35(8):2099-2105
Elemental powders of stoichiometric Al3Ti were mechanically alloyed (MA) in order to investigate the phase formation during the milling process. Furthermore the stability of MA powders were studied under transmission electron microscopy (TEM). The results indicate that a supersaturated Al(Ti) solid solution with nanocrystalline size has been formed after mechanical alloying for 360 ks in consuming the elemental powders of Al and Ti and no further phase transformation can be detected upon longer milling. The MA powders are unstable being irradiated by electron beams under the TEM observation, exothermically forming various intermetallic compounds. The combustion phase transformation processes and products are depending on the time of mechanical alloying. The structural changes and phase transformations during both mechanical alloying process and annealing process were also characterized by using X-ray diffraction measuring. 相似文献
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《Nanostructured Materials》1994,4(7):787-794
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 NiAl system and FeAl system is suggested to be the main cause of the different behaviors of formation between NiAl and FeAl compounds by MA. 相似文献
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采用机械合金化制备Mg70-xTi12+xNi12Mn6(x=8、16、24、32)合金,通过X射线衍射(XRD)、差热分析(DTA)、扫描电子显微镜(SEM)和压强-成分-温度(PCT)分析等方法对合金粉末进行分析和表征。结果表明,随着球磨时间的增加,合金中hcp相所对应的衍射峰减弱,衍射峰宽化,合金中固溶度以及合金化程度提高;当球磨时间为200h时,在合金Mg46Ti36Ni12Mn6和Mg38Ti44Ni12Mn6中出现具有bcc结构的固溶体,Mg70-xTi12+xNi12Mn6(x=8、16、24、32)合金的吸氢量分别为0.83%、0.68%、1.36%和0.41%(质量分数),根据DTA测试结果,Mg70-xTi12+xNi12Mn6(x=8、16、24、32)合金氢化物的第一个吸热峰位置分别为670、688、593和662K。在Mg46Ti36Ni12Mn6合金中添加5%(质量分数)的TiF3和Nb2O5混合球磨后,合金的吸氢量分别增加到了2.33%和2.36%(质量分数),TiF3和Nb2O5能有效地提高Mg-Ti基合金的贮氢性能。 相似文献
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F. G. Cuevas J. Cintas J. M. Montes J. M. Gallardo 《Journal of Materials Science》2006,41(24):8339-8346
A powder mixture of aluminum, 10 wt% titanium, and 1.5 wt% of a wax acting as process control agent (PCA), has been attrition-milled for 2–20 h. Titanium powder had been previously ground to a lower particle size to make it similar to the as-received aluminum particle size. The overall aim of this work was to achieve a metastable titanium solution in the aluminum matrix. Changes with milling time of particle size and shape, microstructure, hardness and other powder characteristics have been studied. Given the used experimental-conditions, a process time of 10 h has been selected for the mechanical alloying (MA) of Al–10Ti powder, attaining a compromise between uniform microstructure development and a not so long processing time. At this milling time aluminum dissolves about 9 wt% Ti, increasing its Vickers microhardness (202 VH20) more than 10 times with reference to the starting Al powder (20 VH20). Milled particle size is smaller than the starting one (17 vs. 44 μm). Increasing milling for longer times, up to 20 h, does not produce important changes in powders structure. 相似文献
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The mixture of the Ni, Fe and Mo elemental powders with the nominal composition of the Supermalloy was milled in a planetary mill under Ar atmosphere. Several milling times have been used ranging from 4 to 16 h. A heat treatment of 30 min, 1, 2 and 4 h at temperature of 350°C has been performed in vacuum in order to improve the alloying process and remove the internal stresses. The formation of the Fe-Ni-Mo alloys by mechanical alloying was evidenced by X-ray diffraction. The nanocrystalline Supermalloy powders have been obtained after 16 h milling and after 8 h milling followed by 4 h annealing. A typical grain size of 11 ± 2 nm have been obtained after 16 h milling. The chemical homogeneity composition and the morphology of the powder particles have been studied by X-ray microanalysis and scanning electron microscopy respectively. 相似文献
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为了研究球磨参数对ODS奥氏体不锈钢机械合金化效果的影响,以Fe、Cr、Ni、W、Ti纯金属元素粉末和纳米Y2O3为原料进行混合(配比为Fe-18Cr-8Ni-2W-1Ti-0.35Y2O3,质量分数),通过高能球磨的方式实现混合粉末的机械合金化.研究球磨时间、转速的变化对粉末粒度、成分均匀度和固溶程度的影响.结果表明,在真空环境下,球料比为10∶1、转速为380r/min、球磨时间60h时,粉末达到了很好的机械合金化效果,成分分布均匀;当球磨时间延长到100h时,粉末颗粒达到最细,继续球磨,粉末将出现明显的团聚.对最优机械合金化工艺参数获得的粉末进行热压致密化研究表明,随着温度的升高,试样的密度随之升高,维氏硬度随之降低. 相似文献
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《Materials Science & Technology》2013,29(8):925-933
AbstractNanostructured alloys have considerable potential as soft magnetic materials. In these materials a small magnetic anisotropy is desired, which necessitates the choice of cubic crystalline phases of Fe, Co, Ni, etc. In the present work, Fe–50 at.-%Co alloys were prepared using mechanical alloying (MA) in a planetary ball mill under a controlled environment. The influence of milling parameters on the crystallinity and crystal size in the alloys was studied. The particle size and morphology were also investigated using SEM. In addition, a thermal treatment was employed for partial sintering of some of the MA powders. The crystal size in both MA powders and compacted samples was measured using X-ray diffraction. It was shown that the crystal size could be reduced to less than 15 nm in these alloys. The nanocrystalline material obtained was also evaluated for magnetic behaviour. 相似文献