机械球磨制备Fe纳米晶及其Mossbauer效应

在不同气氛下应用球磨法制备了金属Ｆｅ纳米晶粉末，用Ｘ射线衍射分析球磨前后样品的结构变化，Ｍｏｓｓｂａｕｅｒ谱研究了纳米晶的结构特性。结果表明，不同气氛显著影响纳米晶界面组元的电子结构和磁性结构。     

Ni对高能球磨Mg-Ni合金组织和电化学性能的影响

利用高能球磨工艺制备了不同Ni含量的Mg-Ni合金，采用X射线衍射分析，研究了随Ni含量变化以及球磨时间不同合金组织演变过程，并对其电化学放电容量进行了测试分析。结果表明，随着Ni含量由Mg2Ni，Mg1．5Ni到MgNi的增加，高能球磨Mg—Ni合金体系经历纳米晶Mg2Ni向非晶MgNi过渡并最终形成纳米晶MgNi合金的转变过程。不同组织状态的Mg-Ni合金其电化学容量有较大的差异。随着Ni含量提高，纳米晶MgNi合金增加，在有纳米晶Ni的存在下，Mg-Ni合金的放电容量可高达500mAh／g。延长球磨时间，获得几乎完全纳米晶的MgNi合金组织，由于没有纳米晶Ni的催化作用，导致合金放电容量下降。     

机械合金化对Fe_（73．5）Cu_1Nb_3Si_（13．5）B_9纳米晶合金

研究了Ｆｅ７３．５Ｃｕ１Ｎｂ３Ｓｉ１．Ｂ９纳米晶合金在机械合金化过程中结构的变化，发现将已经形成纳米晶的合金带经过短时间的机械球磨以后可以使它变为非晶态粉末。若延长球磨时间可使非晶粉末再出现昌化，并具有更小的晶粒。若将此非晶态粉末再进行退火可形成晶粒更微小的纳米晶。     

机械合金化对Fe73.5Cu1Nb3Si13.5B9纳米晶合金结构的影响

研究Ｆｅ７３．５Ｃｕ１Ｎｂ３Ｓｉ１３．５Ｂ９纳米晶合金在机械合金化过程中的结构的变化，发现将已经形成纳米晶的合金带经过短时间的机械球磨以后可以使它变非晶态粉末，若延长球磨时间可使非晶粉末再出晶化，并具有更步的晶粒。若将以非晶态粉末再进行退火可形成晶粒更微小的纳米晶。     

粗晶和纳米晶FeAs的微观结构与磁学性能

研究粗晶及纳米晶FeAs的微观结构和磁学性能.首先通过高能球磨和热处理制备粗晶FeAs,随后将粗晶FeAs进行不同时间球磨得到纳米晶FeAs.结果表明,球磨时间为32 h时,平均晶粒尺寸由>100 nm减小到32.4 nm,同时内应变增加到0.568％.随着球磨时间的增加,矫顽力由球磨前的29.2 kA/m降低到15....     

纳米晶W粉和W-Ni-Fe预合金粉的制备

采用高能球磨法制备纳米晶W粉和W-Ni-Fe预合金粉，研究了不同的球磨材质包括硬质合金球(CCB)、钨球(TAB)和球磨转速、球料比及球磨时间等条件对球磨后粉末性能的影响。利用XRD，TEM和EDX分析球磨后粉末的晶粒尺寸、晶格畸变、形貌、结构变化及颗粒成分变化。结果表明：高能球磨法可制得10nm～80nm的W粉和W-Ni-Fe预合金粉，纳米级颗粒含量达80％以上。相同材质的钨球制得的纳米粉末综合性能较好。球磨过程中，粉末保持颗粒状结构，纳米级粉末颗粒形状最终趋于等轴化。     

高能球磨制备Al-Pb-Si-Sn-Cu纳米晶粉末的特性

通过机械合金化制备了Al-15％Pb-4％Si-1％Sn-1．5％Cu(质量分数)纳米晶粉末。采用X射线衍射(XRD)，扫描电镜(SEM)和透射电镜(TEM)对不同球磨时间的混合粉末的组织结构、晶粒大小、微观形貌以及颗粒中化学成分分布情况进行了研究。结果表明混合粉末经过球磨后形成了纳米晶，其组织非常均匀。球磨对Pb的作用效果明显大于对Al的作用效果，经过40h球磨后Pb粒子达到40nm，而Al在球磨60h后晶粒为65nm；经球磨后，Cu和Si固溶于Al的晶格中，而Sn则固溶于Pb晶格中，并且Al和Pb发生了互溶，形成了Pb(Al）超饱和固溶体；在球磨过程中硬度高的脆性粒子Si难于完全实现合金化。     

纳米晶Cu_30Al_70合金的形成及其催化活性

本文利用机械球磨的方法将工业上广泛应用的传统的ＲａｎｅｙＣｕ催化剂的前体Ｃｕ３０Ａｌ７０合金制成了纳米晶合金催化材料，并研究了它在木糖加氢反应中的催化活性．结果表明，制成的纳米晶合金ＣｕＡｌ２相的平均晶粒尺寸为１２ｎｍ，球料比和球磨时间极大地影响形成的纳米晶Ｃｕ３０Ａｌ７０合金的晶粒尺寸，纳米晶Ｃｕ３０Ａｌ７０合金组织较均匀，元素分布均匀，活化后的催化剂具有较高的催化活性．     

高能球磨Ti55.5Cu18.5Ni17.5Al8.5合金非晶化研究

采用机械合金化(MA)制备出Ti_(55.5)Cu_(18.5)Ni_(17.5)Al_(8.5)非晶粉末。利用X射线衍射仪(XRD)、示差扫描量热分析仪、扫描电镜、透射电镜等研究了不同球磨时间粉末的微观形貌以及非晶化行为,探讨了非晶化对合金硬度的影响。结果表明,首先随着球磨时间的增加,微观组织的演变规律是合金晶粒逐渐变小,出现纳米晶化合物;随后纳米晶化合物内部发生局部结构长程无序化,纳米晶化合物分割成更为细小的纳米晶;最终纳米晶颗粒完全非晶化。从原子尺度证明了非晶化的主要原因是高能球磨过程中发生了剧烈塑性变形,形成了高密度位错以及严重的晶格畸变,最终导致原子长程无序化从而形成非晶。球磨引起加工硬化和非晶晶化,使得球磨后的合金粉末硬度显著增加。     

机械合金化过程中Fe50Als50二元系的结构演变

利用高能球磨和后续热处理技术制备纳米晶Fe5A150（摩尔分数，％）合金粉体。采用X射线衍射、透射电镜和扫描电镜对元素混合粉在机械合金化过程中的结构演变及热处理对合金化粉体结构的影响等进行分析，讨论其机械合金化合成机制。结果表明：球磨过程中Al向Fe中扩散，形成Fe（A1）固溶体。机械合金化合成Fe（Al）遵循连续扩散混合机制；球磨30h后，粉体主要由纳米晶Fe（A1）构成，晶粒尺寸5．65nm；热处理导致Fe（A1）纳米晶粉体有序度提高，转变为有序的B2型FeAl金属间化合物，粉体的晶粒尺寸增大，但仍在纳米尺度范围。     

Mechanically activated disproportionation of NdFeB alloy by ball milling in hydrogen

1　INTRODUCTIONSincethediscoveryoftheuniaxialNd2 Fe14 Bcompoundin 1983[1,2 ] ,theNdFeBalloyshavebeenwidelyusedforpermanentmagnetapplicationsowingtotheirexcellentmagneticproperties ,suchashighcoercivity ,high energy products[3,4 ] .Intheserareearthpermanentmagnets ,afurtherexcitingrecentdevelopmentisthesuggestionofnano compositeex changemagnetscombiningthelargecoercivitiesinhardmagnetswithlargeinductionsfoundinsoftertransitionmetalmagnets[5,6 ] .Indeed ,thenano com positemagnetshavebeent…     

Fe-Al复合粉在高能球磨时的组织转变及真空烧结的FeAl基合金的力学性能研究

研究了机械球磨与真空烧结制备FeAl基合金的工艺——球磨过程中Fe-Al粉末的结构转变及FeAl基烧结体的微观结构和力学性能。结果表明,Fe、Al单质混合粉末经机械球磨可得到具有Fe、Al相间层片结构的复合粉,且球磨时间越长,Fe、Al复合粉的层片结构越薄越均匀。FeAl基材料优异的室温力学性能与晶粒细化、组织均化效应有关。     

Fe-Al复合粉在高能球磨时的组织转变及真空烧结的FeAl基合金的力学性能研究

研究了机械球磨与真空烧结制备FeAl基合金的工艺——球磨过程中Fe-Al粉末的结构转变及FeAl基烧结体的微观结构和力学性能。结果表明，Fe、Al单质混合粉末经机械球磨可得到具有Fe、Al相间层片结构的复合粉，且球磨时间越长，Fe、Al复合粉的层片结构越薄越均匀。FeAl基材料优异的室温力学性能与晶粒细化、组织均化效应有关。     

Phase Transformation and Magnetic Property of Ni-Mn-Ga Powders Prepared by Dry Ball Milling

This study investigated the phase transformations and magnetic properties of Ni-Mn-Ga alloy powders prepared by dry ball milling in argon atmosphere. The Fe and Cr elements were found to be introduced in the alloy after ball milling, which should result from the severe collision and friction among the particles, balls, and vial. The x-ray diffraction result indicated that the Fe and Cr elements should have alloyed with the Ni-Mn-Ga matrix. The martensitic transformation temperature and Curie temperature of the 800?°C annealed powders decreased by ~33?°C and increased by ~28?°C, respectively, as compared to that of the bulk alloy. The comprehensive effect of the changing of valence electron concentration of the alloy due to the introduction of Fe and Cr and the grain refinement of the alloy caused by ball milling should be responsible for the reduction of martensitic transformation temperature. The saturation magnetization of the 800?°C annealed powders became larger (~5?emu/g) than that of the bulk alloy. The enhancement of magnetic properties, such as the increase of Curie temperature and enhancement of saturation magnetization of the annealed Ni-Mn-Ga powders, should be attributed to the increase of magnetic exchange caused by introduction of Fe in the alloy. The contaminations of Fe and Cr elements emerging from the dry ball milling process changed the phase transformation and magnetic properties of the Ni-Mn-Ga alloy. Therefore, the dry ball milling process is difficult to control the contamination from the milling medium and not suitable to prepare Ni-Mn-Ga powders. On the contrary, the wet ball milling method under liquid medium should be a better method to prevent the contamination and fabricate pure Ni-Mn-Ga ferromagnetic shape memory alloy powders.     

High spatial resolution PEELS characterization of FeAl nanograins prepared by mechanical alloying

We investigate the nanograin “chemical” structure in a nanostructured material of possible industrial application (Fe–Al system) prepared by conventional mechanical alloying via ball milling in argon atmosphere. We restrict ourselves to the structural and nanochemical behaviour of ball-milled nanocrystalline Fe–Al powders with atomic composition Fe₃Al, corresponding to a well-known intermetallic compound of the Fe–Al system. Scanning transmission electron microscopy (STEM) equipped with a parallel detection electron energy loss spectrometer (PEELS) has provided an insight on the “chemical” structure of both nanograins and their surface at a spatial resolution of better than 1 nm. The energy loss near edge structure of the Al L loss reveals that the Al coordination is similar to a B2 compound and the oxidation of the powder during processing may play a significant role in the stabilization of the intermetallic phases. Conventional transmission electron microscopy (TEM) was used for the structural characterization of the material after the ball milling; powder X-ray diffraction (XRD) aided the investigation.     

Mechanical alloying characteristic and thermal stability of Al_(78)Fe_(20)Zr_2 amorphous powders

The powders of pure Al, Fe, and Zr for preparing Al78Fe20Zr2 were subject to a high-energy planetary ball milling.The microstructure evolution of the mixtures at the different intervals of milling was characterized by X-ray diffraction(XRD), transmission electron microscopy(TEM) and differential scanning calorimetry(DSC).It was found that a nearly complete amorphization could be achieved in the mixtures after ball milling for 23 h.Further ball milling led to the crystallization of the amorphous powders.A long time ball milling, e.g., 160 h, led to a complete crystallization of the amorphous powders and the formation of Al3Zr and Al13Fe4.The crystallization products caused by ball milling are almost the same as that produced by isothermal annealing of the amorphous powders in vacuum at 800 K for 1 h.     

球磨纯铁中纳米铁素体的形成机制

通过形貌观察和硬度测试研究了球磨纯铁中纳米铁素体的形成机制，结果表明，在球磨过程初期，纳米铁素体首先在球磨颗粒的表层区域形成并呈现层片状结构，扫描电镜（SEM），透射电镜（TEM）和高分辨电镜（HREM）观察表明，层片状纳米铁素体区与颗粒内部加工硬化区具有不同的微观结构，而且它们之间的界面十分明显，显微硬度测试试表明，前者的硬度数值明显高于后者，进一步的球磨过程导致颗粒细化并完成转变为纳米铁素体，分析表明，纳米铁素体的形成是由于球磨过程中加工硬化效应产生的位错胞墙结构向晶界结构转变而导致的，这也是造成加工硬化区与纳米铁素体之间存在的硬度差异的原因。     

Densification of Ni-NiFe_2O_4 cermets for aluminum electrolysis

1INTRODUCTION Aluminumelectrolysisconsumesenormous energyandresources,andtheconsumptionwillbeconsiderablydecreasedbyintroductionofinert anodeandwettablecathode.However,underthe toughworkingconditionofaluminumelectrolysis,i.e.highlycorrosiveNa3AlF6Al2O3moltensalts athightemperature(940960℃),theinert anodesnecessaryforthesuccessfulproductionofaluminummighthavethefollowingproperties:be insolubleinafluoridemelt,beresistanttowards anodeoxygen,havegoodelectricalconductivity,possessadequatestr…     

Synthesis and characteristics of W-Ni-Fe nano-composite powders prepared by mechanical alloying

1　ＩＮＴＲＯＤＵＣＴＩＯＮＴｕｎｇｓｔｅｎ ｂａｓｅｄｈｅａｖｙａｌｌｏｙｉｓａｕｎｉｑｕｅｍａｔｅｒｉａｌｄｕｅｔｏｔｈｅｃｏｍｂｉｎａｔｉｏｎｏｆｉｔｓｈｉｇｈｄｅｎｓｉｔｙ ,ｈｉｇｈｓｔｒｅｎｇｔｈ ,ｈｉｇｈｄｕｃｔｉｌｉｔｙ ,ｈｉｇｈｃｏｎｄｕｃｔｉｖｉｔｙａｎｄｇｏｏｄｍａｃｈｉｎａｂｉｌｉｔｙ[1,2 ].Ｉｔｉｓｗｉｄｅｌｙｕｓｅｄｆｏｒｒａｄｉｏａｃｔｉｖｅｓｈｉｅｌｄｉｎｇ,ｉｎｅｒｔｉａｌａｎｄｍｉｌｉｔａｒｙ ｐｅｎｅｔｒａｔｉｎｇａｐｐｌｉｃａ ｔｉｏｎｓ.ＦｕｌｌｙｄｅｎｓｅＷ Ｎ…     

Addition of catalysts to magnesium hydride by means of cold rolling

In this paper we compare the techniques of cold rolling and ball milling as a mean to synthesized nanocomposites MgH₂ + 2 at.%X where X = Co, Cr, Cu, Fe, Mn, Nb, Ni, Ti, V. High energy ball milling was performed under argon for 30 min while cold rolling was done in air with a number of roll limited to five. Particle and crystallite sizes are smaller in the ball milled compounds than in the cold rolled ones. The hydrogen sorption kinetics of the ball milled compounds was also faster than the cold rolled samples but not by a wide margin. Because cold rolling was done in air, this limited the number of rolls that could be performed. It is expected that rolling under protective atmosphere will enable a higher number of rolls and better sorption kinetics.