W-Ni-Fe nanostructure materials synthesized by high energy ball milling

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Effect of ball milling time on microstructure and properties of Laves phase NbCr2 alloys synthesized by hot pressing

Laves phase NbCr2 alloys with a composition of Nb-66.7Cr (molar fraction, %) were prepared by mechanical alloying and hot pressing. The microstructures and properties of the Laves phase NbCr2 alloys, prepared from elemental niobium and chromium powders under various ball milling time by hot pressing at 1 250 ℃ for 0.5 h, were investigated. The results indicate that if the ball milling time is longer than 40 h, the synthesizing reaction of Laves phase NbCr2 can be accomplished much sufficiently. Then the nearly full-dense Laves phase NbCr2 alloys can be prepared by hot pressing from ball milled powders with more than 40 h. The hot pressing sample with homogeneous and fine microstructure made from 40 h ball milled powders has the optimum microstructure and properties. It has a relative density of 98.1%, Vickers hardness of 11.4 GPa, compress strength of 1 981 MPa and fracture toughness of 4.82 MPa·m1/2. The effect of fine grain toughening is fully realized.     

3Fe/Al混合粉末的高能球磨及环境介质的相互作用

利用Fritsch Pulversitte 5型行星式球磨机、扫描电子显微镜、X射线光电子能谱仪和X射线衍射仪研究了3Fe/Al元素混合粉末的机械球磨过程以及球磨过程中混合粉末与环境介质的相互作用.研究证实,球磨过程中存在颗粒断裂、冷焊机制,球磨20h产物为α-Fe(Al)固溶体,其表面生成一层由Fe2O3和Al2O3组成的氧化膜.     

高能球磨制备纳米TiC粉末

应用高能球磨机,用Ti和C粉末在室温下全盛了纳米级TiC晶粒,并对合成后的粉末进行了微观组织分析,实验结果表明：用机械合金化（MA）法可以在比较短的时间内合成TiC粉末,其合成机理为机械碰撞诱发的自蔓延反应机理,经过球磨反应可以得到平均颗粒大小为5.641um,并且具有10nm左右的纳米晶粒TiC粉末,DAT分析表明,利用加热方法合成TiC必须在636.5℃以上才能进行,而通过球磨工艺可以使该合成过程在室温下进行。     

钼硅混合粉末在机械合金化过程中的结构演变

采用X射线衍射仪（XRD）和差热分析仪（DTA）研究了Mo-67at%Si元素混合粉末在中等强度的机械研磨（合金化）过程中的结构变化过程，结果表明，在中等强度的研磨过程中，β－MoSi2是初生相，且在随后的研磨过程中非晶化；在高研磨强度下生成α－MoSi2的量大于β－MoSi2,且α－MoSi2的含量随研磨时间的增加而增加，差热分析表明亚稳相β－MoSi2随温度的升高会向α－MoSi2转变。     

The synthesis of nanocrystalline Ni75Nb12B13 alloys by high energy ball milling of elemental components

Ni₇₅Nb₁₂B₁₃ alloys were synthesized by mechanical alloying (MA) of individual Ni, Nb and B components. X-ray investigation showed the formation of Ni (Nb, B) solid solution and amorphous phase at the intermediate stage of milling. Metastable phases formed by MA turned into Ni (Nb), Ni₂₁Nb₂B₆ and Ni₃Nb stable phases during heating up to 720 °C. The exothermal effects on DSC curves were caused with these processes. The disintegration of Ni (Nb, B) solid solution and crystallization of an amorphous phase resulted in the stable phases formation during the milling prolongation as well as after thermal treatment.     

WC粉体的高能球磨超细化

采用高能球磨工艺对WC粉体进行超细研磨。研究了粉体颗粒度及晶粒度的大小随球磨时间的变化关系。发现随球磨时间的增加 ,粉体颗粒度不断细化 ,最后趋于稳定 (0 .4μm) ;粒度分布曲线出现明显的三峰特征 ,分别位于细 (微米 )区、超细 (亚微米 )区和极细 (纳米 )区。研磨细化的WC粒子具有纳米晶 (1 0nm)结构。探讨了WC粉体高能球磨细化机理与纳米晶结构特性。     

nano-SiC_p/Al复合材料的高能球磨制备工艺

采用高能球磨粉末冶金法制备了10vol%nano-SiC颗粒增强纯Al基复合材料,研究了球磨时间和硬脂酸含量对复合粉末粒度和纳米颗粒分散均匀性的影响规律,并对复合材料的微观结构和拉伸性能进行了研究.结果表明,随球磨时间的延长,SiC颗粒在Al 中的分散均匀性变好,而复合粉颗粒的粒径先减小后增大,在球磨时间为15 h、过程控制剂硬脂酸含量为2wt%时复合粉末粒径最小.并采用此优化的混料工艺,制备出综合性能良好祅ano-SiCp/Al复合材料,其抗拉强度达到392.7 MPa,较纯Al提高了164.9%,伸长率达10.41%,较纯Al有所下降.复合材料的断裂机制是微孔聚集型断裂.     

高能球磨制备Fe-Cu纳米晶过饱和固溶体

对Fe-20at%Cu合金粉末进行了高能球磨,并利用XRD对Fe-Cu二元合金粉末在球磨过程中的物相变化进行了分析。结果表明,球磨30 h后形成了Fe(Cu)纳米晶过饱和固溶体。热力学计算分析指出,Fe-Cu二元系不具有形成过饱和固溶体的热力学驱动力。高能球磨在Fe-Cu二元互不溶体系中扩展固溶度的驱动力是动力学驱动。在随后的退火过程中,纳米晶过饱和固溶体发生分解。     

Ni（OH）2 particles synthesized by high energy ball milling

1 Introduction Ni(OH)2/NiOOH has been used as positive materials in alkaline secondary batteries for more than 100 years[1- 3]. The performance improvement of Ni(OH)2/NiOOH electrode is crucial for the application of these batteries as they are all positi…     

Synthesis of TiAl-Al2O3 composites by high energy milling and hot-press sintering

A sub-microstructure titanium aluminide alloy/Al2O3 （3A） composite was obtained by crystallization of the amorphous powders, which were prepared by mechanical alloying （MA） in a planetary ball milling system using Ti-AI-TiO2 as raw materials. The experimental results show that, when the milling time increases up to 30 h, the hep Ti（Al） supersaturated solid solution disappears, only amorphous phase is left. The compact samples were synthesized by hot-press to 1 200 ℃ with the amorphous as a precursor; the final phases of the matrix and strengthened phase are y-TiAl and Al2O3. The phases come from in situ crystallization and transformation. The samples, fabricated from the amorphous phase by hot press sintering, have high bending strength and fracture toughness.     

高能球磨制备Ti-50%Al复合粉末的表征(英文)

采用高能球磨法制备了Ti-50%Al(摩尔分数)复合粉末,利用SEM、TEM、HREM、HAADF-STEM分析手段对复合粉末颗粒的表面形貌、结构及组成进行了表征。在球磨过程中钛、铝之间逐渐发生反应并形成无序的Ti/Al相;球磨9h后铝逐渐融入钛中,产生纳米晶钛铝固溶体,同时引起大量高密度位错。合金化后粉末的元素组成接近原始成分,但分布极不均匀。     

Preparing nano-crystalline rare earth doped WC/Co powder by high energy ball milling

The nano-crystalline rare earth doped WC/Co powder was prepared by high energy ball milling. The nano-crystalline powders were characterized by means of XRD (X-ray diffraction), SEM (scanning electron microscope) and DTA (differential thermal analysis). The results show that adding trace rare earth elements into carbides is effective to minish the grain size of WC/Co powder. The grain size of rare earth doped powder became two times smaller as compared with the undoped powder within ball milling times of 25–45 h. The XRD peak of Co phase disappeared after 25 h ball milling. A sharp peak of heat release at the temperature of 597 °C was emerged in DTA curve within the range of heating temperature. After consolidated the rare earth doped WC/Co alloy by high energy ball milling exhibits ultra-fine grain sizes and better mechanical properties.     

Bulk Al/SiC nanocomposite prepared by ball milling and hot pressing method

Nano-sized Al/SiC powders were prepared by mechanical alloying method. Two sorts of SiC particle, i.e., nano-sized and popular micron-sized SiC were utilized. The particle size and microstructure of the milled powder were characterised. Effects of the particle size and agglomerate state of SiC, as well as the microstructure of Al/SiC nanocomposite were studied by SEM and TEM. The results show that nano-sized SiC particles is dispersed in aluminium uniformly after ball milled for only 2 h, whereas the similar process need about 10 h for popular micron-sized SiC particle. The bulk Al/SiC nanocomposite can be fabricated by hot pressing the nano-sized Al/SiC powders at temperature about 723 K under pressure of 100 MPa.     

Al-2.5%Pb合金在高能球磨和烧结过程中的组织结构变化

用机械合金化方法制备了Al-2.5wt%Pb合金,采用X射线衍射仪（XRD）和扫描电子显微镜（SEM）分析了Al-2.5wt%Pb合金在高能球磨和烧结过程中的组织结构变化。结果表明,该合金粉末经30 h球磨后,可以获得纳米级Pb颗粒均匀弥散分布在Al基体上的组织。在随后的烧结过程中,纳米相Pb的长大可以用Ostwald熟化的经典-LSW理论来描述。     

Influence of high-energy ball milling on Al-30Si powder and ceramic particulate

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球磨方式对纳米晶Mg2FeH6储氢材料合成与放氢性能的影响

分别应用Uni-Ball-Mill 5和XQM-4变频行星式球磨机将Mg粉和Fe粉在氢气中直接球磨合成三元储氢相Mg2FeH6。采用球磨罐中的氢压降、X射线衍射谱、扫描电镜、热分析、吸放氢测试等测试手段研究了不同球磨方式对纳米晶Mg2FeH6储氢材料的合成结果。结果表明,XQM-4变频行星式球磨机球磨150 h,Mg2FeH6相的产率（质量分数）接近70%;在100 kPa氢压下,380℃放氢量为2.66%,粉末呈片状,晶粒在7 nm以下。而采用Uni-Ball-Mill 5球磨机P2方式球磨270h,Mg2FeH6相的产率仅为39.1%,100 kPa氧压下,350℃放氢量为1.15%,粉末呈球状。两者的差别可能源于前一种球磨方式具有更高的球磨合金化效率。     

Al-20%Sn-4.5%Cu合金在高能球磨和烧结中的组织

利用机械合金化方法制备Al-20%Sn-4.5%Cu合金粉末,将之压制成型后进行烧结.用X射线衍射仪(XRD)、扫描电镜(SEM)和差示扫描量热仪(DSC)分析了Al-20%Sn-4.5%Cu合金在高能球磨和烧结过程中的组织变化.结果表明,该合金粉末经40 h球磨后,可以获得纳米级Sn颗粒均匀弥散分布在Al基体上的组织,并且形成了Al(Cu)过饱和固溶体;在随后的烧结过程中,Sn相尺寸仍保持在200 mm左右,Al(Cu)过饱和固溶体则以CuAl2相的形式脱溶析出.     

快速凝固Al-Fe-V-Si-Nd合金中纳米相转变动力学

应用M ssbauer谱 ,X射线衍射 (XRD)和差式扫描量热法 (DSC)研究了颗粒弥散的快速凝固Al 4.3Fe 0 .7V 1.7Si 1.0Nd(摩尔分数 ,% )合金中纳米相的转变和相变动力学 ,并用Arrami公式X =1-exp(-Ktn)计算了纳米相转变的激活能。结果表明 :快速凝固纳米合金在加热过程中发生Al8Fe4 Nd相向α Al13 (Fe,V) 3 Si相转变 ,α Al13 (Fe,V) 3 Si相生成所需的激活能E =(2 .48± 0 .0 9)eV ,与Fe原子在α Al中的扩散激活能相一致 ,说明α Al13 (Fe ,V) 3 Si相的形核长大主要由Fe原子的体扩散控制。