球磨与烧结对Al2Ti3V2ZrB/2024Al复合材料组织与硬度的影响

利用粉末冶金方法制备了Al2Ti3V2ZrB/2024Al复合材料,研究了球磨工艺和烧结温度对复合材料微观组织和硬度的影响。结果表明,球磨时过高的球磨速度或过长的球磨时间均会造成Al2Ti3V2ZrB颗粒的团聚,影响复合材料的组织均匀性。在球磨速度为150r/min下球磨5h,Al2Ti3V2ZrB颗粒在2024Al基体中的分布最均匀,复合材料的硬度最高。当烧结温度低于510℃时,Al2Ti3V2ZrB颗粒在2024Al基体中分布比较均匀,复合材料密度和硬度随烧结温度升高逐渐增加;超过510℃后Al2Ti3V2ZrB颗粒开始团聚,复合材料密度和硬度下降,在510℃制备的复合材料具有最高的硬度。     

球磨工艺对Mg2B2O5w/6061Al基复合材料微观组织演变及力学性能的影响

采用粉末热挤压法制备了硼酸镁晶须增强铝基复合材料,对球磨工艺参数、粉末特性及热挤压态复合材料间的相互关系进行了研究。研究结果表明,在球磨过程中,增强体晶须的添加促进了基体合金的变形,加快了铝粉颗粒的焊合与断裂过程的发生。在球磨过程中,经过适当时间的高速球磨后,铝合金基体晶粒尺寸减小,增强体晶须在基体中的分布得到显著改善,从而使热挤压态复合材料力学性能得到大幅度的提高。     

球磨工艺对原位合成纳米级TiB的影响

球磨工艺对球磨粉末及其烧结组织的微观结构和形态都有重要的影响。本实验采用低能和高能球磨两种方式对Ti-Al-0.2B wt.%合金粉末进行球磨,研究球磨过程中粉末组织和形态的变化,并将球磨后的粉末进行热压烧结,研究不同球磨方式对烧结组织中原位合成TiB增强相形态的影响。研究结果表明：低能球磨过程中粉末颗粒间有机械合金化发生,其烧结组织中生成的TiB为细长态,在基体中分布均匀,没有联结的粗晶或成簇生长现象。对于高能球磨,粉末颗粒细化效果明显,颗粒平均尺寸降至1 μm,球磨过程中除了机械合金化还形成了Ti(Al)过饱和固溶体,并在球磨后期形成了非晶结构。经高能球磨的粉末烧结后,组织中生成了均匀分布的纳米级TiB晶须。     

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.     

高能球磨掺杂氧化物粉体和压敏陶瓷粉体对氧化锌压敏陶瓷性能的影响(英文)

采用高能球磨掺杂氧化物粉体和压敏陶瓷粉体2种不同制备技术制备ZnO-Bi2O3压敏陶瓷,通过扫描电镜和X-射线衍射对其显微组织和相成分进行分析,探讨不同高能球磨制备技术对氧化锌压敏陶瓷电性能和显微组织的影响。结果表明:压敏陶瓷粉体高能球磨是制备高性能氧化锌压敏陶瓷的一种优异的技术,在1000°C下烧结3h,压敏陶瓷的电位梯度为617V/mm,非线性系数为57;压敏陶瓷的致密度高达95%,显微组织均匀、致密;高能球磨压敏陶瓷粉体可细化晶粒,增强烧结驱动力,加速烧结过程,降低烧结温度。     

高能球磨制备Al3Ti/Al块体纳米晶复合材料

通过对Al Ti系和Al TiO2 系进行高能球磨和压制烧结制备了固态原位反应生成的纳米晶块体Al3Ti/Al复合材料。研究表明 :Al Ti合金系高能球磨后 ,各组元晶粒得到细化 ,并且Ti在Al中发生了强制超饱和固溶 ,烧结时原位反应形成纳米晶Al3Ti/Al复合材料 ;而Al TiO2 反应体系高能球磨仅发生组分晶粒细化 ,烧结时TiO2 部分还原并和Al原位反应生成纳米晶 (Ti2 O3 Al3Ti) /Al复合材料。     

Preparation of WC nanoparticles by twice ball milling

In order to improve the ball milling efficiency of WC powders and thus to fabricate nano-grained WC–Co cemented carbides with high mechanical properties, WC nanoparticles were prepared by twice ball milling in nylon vessels. The best technology to disperse WC powders in alcohol was investigated at first. Based on the dispersion results, 2 wt.% PEG was used with La₂O₃ as additive to improve ball milling efficiency. The particle size, crystal structure, surface morphology and surface properties were tested by a laser particle sizer, XRD, FE-SEM and FT-IR, respectively. During the first ball milling, sample d achieved the best milling performance, including average particle size (168 nm) and grain size (27.2 nm) among samples a (pure WC), b (with PEG), c (with La₂O₃) and d (with PEG and La₂O₃). La₂O₃ could greatly decrease particle size and grain size while PEG could narrow particle size distribution. During the second milling, the particle size and grain size of sample d reached 89 nm and 13.2 nm at 96 h, respectively. The results indicated that twice ball milling can greatly improve particle size and grain size compared with the first ball milling, and further narrow the size distribution. In conclusion, multiple ball milling can reduce the particle size of certain powders with suitable milling technology.     

混杂增强(CNTs+TiB2)/Cu复合材料制备与性能

本文以碳纳米管（CNTs）和TiB2颗粒作为增强相,首先利用球磨、表面吸附和热压烧结相结合技术制备具有层叠结构的CNTs/Cu复合材料,改善了CNTs在铜基复合材料中易团聚问题。CNTs/Cu复合材料的致密度和导电率随CNTs含量增加而降低,抗拉强度和伸长率随CNTs含量增加先升高后降低,当含量为0.1 wt.%时综合性能最优,致密度、导电率和抗拉强度分别为97.57%、91.2 %IACS和252 MPa。而球磨后热压烧结的1 wt.% TiB2/Cu复合材料致密度、导电率和抗拉强度分别为97.61%、58.3 %IACS和436 MPa。在此基础上,将TiB2颗粒原位引入到具有层叠结构的CNTs/Cu复合材料,制备获得混杂增强(CNTs+TiB2)/Cu复合材料。相比单一CNTs（或TiB2）增强铜基复合材料,(CNTs+TiB2)/Cu复合材料的强度提升显著。其中,(0.1 wt.% CNTs+1 wt.% TiB2)/Cu复合材料的导电率和抗拉强度分别为56.4 %IACS和531 MPa,相比1 wt.% TiB2/Cu,其导电率仅降低3.3%,而抗拉强度则升高21.8%。这主要归因于片层间CNTs可起承担和传递载荷作用,同时片层间弥散分布的TiB2颗粒可以钉扎位错,两种强化机制共同作用使(CNTs+TiB2)/Cu复合材料的抗拉强度显著提升。     

Phase transition of Ni-Mn-Ga alloy powders prepared by vibration ball milling

This study investigated the phase transformation of the flaky shaped Ni-Mn-Ga powder particles with thickness around 1 μm prepared by vibration ball milling and post-annealing. The SEM, XRD, DSC and ac magnetic susceptibility measurement techniques were used to characterize the Ni-Mn-Ga powders. The structural transition of Heusler → disordered fcc occurred in the powders prepared by vibration ball milling (high milling energy) for 4 h, which was different from the structural transition of Heusler → disordered fct of the powders fabricated by planetary ball milling (low milling energy) for 4 h. The two different structures after ball milling should be due to the larger lattice distortion occurred in the vibration ball milling process than in the planetary ball milling process. The structural transition of disordered fcc → disordered bcc took place at ∼320 °C during heating the as-milled Ni-Mn-Ga powders, which was attributed to the elimination of lattice distortion caused by ball milling. The activation energy for this transition was 209 ± 8 kJ/mol. The Ni-Mn-Ga powder annealed at 800 °C mainly contained Heusler austenite phase at room temperature and showed a low volume of martensitic transformation upon cooling. The inhibition of martensitic transformation might be attributed to the reduction of grain size in the annealed Ni-Mn-Ga particles.     

球磨工艺和分散剂对陶瓷结合剂粉体解团聚的影响

通过球磨工艺和添加分散剂相结合的方法对陶瓷结合剂团聚体进行解团聚，研究球磨参数和分散剂添加量对解团聚效果及结合剂机械性能的影响，并用激光粒度分析仪、SEM、万能材料试验机测试结合剂粉体解团聚前后的粒度、显微形貌、抗折强度。结果表明:采用小粒径(5 mm)的磨球，添加质量分数为2.5%的分散剂球磨2 h后，结合剂粉体分散性良好，基本没有团聚现象，其D₅₀可降至0.186 μm，且球磨后的粉体在700 ℃烧结后，其抗折强度达到26.2 MPa，比原始团聚体烧结后样品的强度提升了近45%。      

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.     

Metastable phase transitions in Mo-Si and V-Si systems activated by high energy ball milling

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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…     

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.     

Refinement process and mechanisms of tungsten powder by high energy ball milling

The grain refinement process and mechanisms of tungsten powder during ball milling are explored based on different ball milling time. From the results of scanning electron microscopy (SEM), the model for ball milling process is proposed to include four stages: welding stage, squeezing stage, fracturing stage and dynamic balance stage. Microstructure of tungsten powder examined by transmission electron microscopy (TEM) shows that the tungsten powder ball milled for 50 h has polycrystalline grains and most of them have long strip structure with high angle grain boundaries. Nanocrystalline tungsten powder with minimum grain size of 5 nm was obtained in the final stage of ball milling.     

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.     

DEPENDENCE OF SINTERABILITY ON STATE OF AGGLOMERATION OF ULTRAFINE ZrO_2，（Y_2O_3） POWDERS

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Al-TiO_2-B_2O_3系XD合成铝基复合材料研究

主要讨论Al-TiO_2-B_2O_3系XD法制备铝基复合材料的合成工艺及其反应机理。结果表明:在B2 O3 与TiO2 摩尔比小于1时,真空炉温预热至10 0 0K左右时压坯爆燃,反应产物由TiB2 、Al3 Ti和Al2 O3 组成,其中Al3 Ti为棒状物,TiB2 、Al2 O3 为细小颗粒,粒径为数μm左右。同时分析了球磨时间、预紧实度对反应产物的影响规律。     

Effect of composition and milling parameters on the critical ball milling of Ti–Si–B powders

The absence of brittle phases and elevated temperature during ball milling of a powder mixture containing a large amount of ductile component can contribute to reach an excessive agglomeration denoting a critical ball milling (CBM) behavior. This work reports in the effect of composition and milling parameters on the CBM behavior of Ti–Si–B powders. High-purity elemental Ti–Si–B powder mixtures were processed in a planetary ball mill in order to prepare the Ti₆Si₂B compound and two-phase Ti + Ti₆Si₂B alloys. TiH₂ chips instead of titanium powder were used as a starting material. To avoid elevated temperature in the vials during ball milling of Ti–Si–B powders the process was interrupted after each 10 min followed by air-cooling. Following, the milled powders were hot-pressed at 900 °C for 1 h. Samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectrometry (EDS). Short milling times followed by air-cooling contributed to obtain a large amount of powders higher than 75% in the vials. Only Ti and TiH₂ peaks were observed in XRD patterns of Ti–Si–B and TiH₂–Si–B, respectively, suggesting that extended solid solutions were achieved. The large amount of Ti₆Si₂B and Ti + Ti₆Si₂B structures were formed during hot pressing from the mechanically alloyed Ti–Si–B and TiH₂–Si–B powders.     

可变径向切深下螺旋齿球头铣刀微细铣削

微细铣削加工是使用微型立铣刀在高主轴转速下制造微型元件的加工方式,分析切削力和加工稳定性对表征微细铣削加工过程起着重要的作用。提出一种数值分析的方法来研究螺旋齿球头立铣刀在可变径向切削深度下的微细铣削加工过程。首先建立了球头铣刀微细铣削的模型,并推导了切削力的计算公式;采用时域仿真的方法详细计算了螺旋齿球头立铣刀和平头立铣刀铣削加工的切削力,并对比了二者切削力仿真的结果;通过时域和频域研究相结合的方式详细分析了小径向切深下球头铣刀微细铣削的稳定性。最后,分析得到了Hopf-flip分岔,并深入对比和分析了不同加工条件下铣削加工的稳定性状况。