机械合金化法制备(Ag-Cu28)-xSn合金的结构和性能研究

利用机械合金化法制备(Ag-Cu28)-xSn系合金粉末,借助差示扫描量热仪、X-射线衍射仪、扫描电镜等,研究了Sn含量对合金熔化温度、球磨时间对合金粉末的物相组成及显微结构的影响。研究表明:Sn对合金的熔化温度有显著影响,随Sn含量增加合金熔化温度下降趋势减缓;当Sn含量为30%时,合金熔化温度最低为539.3℃。球磨40 h时,(Ag-Cu28)-30Sn粉料合金化完全,其物相组成为Ag4Sn、Cu3Sn和Cu6Sn5。球磨初始阶段(Ag-Cu28)-30Sn粉料颗粒异常长大,球磨至40 h时合金化完成,颗粒断裂和焊合达到平衡,合金粉末粒度均匀,平均粒径约为5~10μm。     

机械合金化制备Ag-Cu_(28)合金过程的研究

采用机械合金化法制备Ag-Cu28二元共晶合金,通过正交试验研究球磨机转速、球料比及过程控制剂对合金化过程的影响,利用XRD、SEM、TG-DSC等方法对球磨粉料的物相组成、微观形貌、熔化特性等进行表征.结果表明:Ag、Cu经过30h球磨,生成了Ag(Cu)过饱和固溶体,其熔化温度为783.8℃,该合金属于亚稳态结构,退火处理后以富银、富铜相形式存在.合金化过程中,硬脂酸作为过程控制剂的加入可以有效地减小颗粒尺寸,但对合金化不利.     

机械合金化制备Ag-Cu纳米晶过饱和固溶体

参考Miedema半经验理论,建立了Ag-Cu系机械合金化(MA)过程的热力学模型。热力学计算分析指出,Ag-Cu二元系不具有形成过饱和固溶体的热力学驱动力;而对机械合金化制备的Ag-20%Cu(原子分数)合金的X射线衍射(XRD)分析表明,机械合金化可以获得Ag-Cu纳米晶过饱和固溶体;这说明Ag-Cu合金经机械合金化形成过饱和固溶体主要来源于动力学驱动。在随后的退火过程中,纳米晶过饱和固溶体发生分解。     

机械合金化制备高纯NiAl粉末

采用机械合金化方法制备NiAl粉末,用XRD和SEM对合成样品进行物相组成和形貌分析,研究了球磨时间和转速对NiAl粉末合成的影响规律.结果表明:球料比6:1,转速500 r/min时,球磨5h后NiAl合成反应基本完成,但由于铝粉的损失,导致合成粉末物相不纯,有少量Ni3Al存在;转速影响机械合金化方法制备高纯NiAl粉,选择合适的转速(365 r/min)可以制得纯NiAl粉.     

纳米晶W-Ti预合金粉的制备与研究

以乙醇为过程控制剂,采用机械球磨法制备Ti含量（质量分数）为10％T 30％、晶粒度在30nm左右的纳米品W-Ti预合金粉末,借助X射线衍射（XRD）、扫描电镜（SEM）和透射电镜（TEM）,研究不同球磨时间的W-Ti预合金粉末的相组成和微观形貌,以期进一步确定含理的纳米晶W-Ti预合金粉末制备工艺和开发出高性能的W-Ti合金靶材。结果表明,随着球磨时间增加,粉末逐渐细化和均匀化,微应变逐渐增加;球磨24h可使W-10％Ti粉末完全合金化,球磨48h后颗粒逐渐转变成片层状,而W-30％Ti粉末在球磨72h后才完全合金化,片层结构更多更明显。2种成分的粉末都生成了固溶体β-W／Ti。     

球磨参数对机械合金化制备Al_2O_3/Mo_5Si_3复合粉体特性的影响

以MoO3粉、Mo粉、Si粉及Al粉为原料,采用机械化学还原法制备了Al2O3/Mo5Si3复合粉体。利用XRD、SEM等对复合粉体在球磨过程中的物相转变和形貌进行表征,并对球磨参数对机械合金化过程的影响进行探讨。结果表明,原料粉体球磨10 h后转变为Al2O3/Mo5Si3复合粉体,反应较完全。随球磨时间延长,复合粉体细小均化,粉体粒度较小,球磨20h后粉体粒度在3~5μm之间,随球磨转速的提高,球磨时间延长,球磨提供能量提高,反应开始时间变短。     

机械合金化法制备含Nd多元铁基合金粉末微观组织结构分析

根据Inoue经验原则设计了一种添加Nd元素多元铁基合金,其成分为 Fe56-x Co7 Ni2 Zr10 Mo5 B20 Ndx （ x=0．2%、0．5%、0．8%,原子分数%）,并通过机械合金化法制备了该合金粉末。利用X射线衍射（XRD）、扫描电镜（ SEM）、差示扫描量热仪（ DSC）研究了Nd含量对多元铁基合金粉末组织结构与热稳定性能的影响。结果表明：在球磨转速300 r/min、球料比30∶1、球磨时间为40 h的条件下,所制备的含Nd多元铁基合金粉末均含有部分的非晶相;球磨后的粉末大多呈近球形,Nd含量为0.8%（原子分数）时,合金粉末颗粒尺寸最为细小且热稳定性较高。     

机械合金化对Cu_(60)Cr_(40)合金微波烧结组织的影响

采用机械合金化和冷压微波烧结的方法制备Cu_(60)Cr_(40)合金,研究了球磨时间对粉末粒度及合金显微组织的影响。结果表明:球磨36~60 h时,Cu_(60)Cr_(40)合金粉体呈层片状,随球磨时间延长,合金粉体细化,机械合金化程度提高;500 MPa冷压后,Cu_(60)Cr_(40)合金压坯断口呈典型的冰糖状断裂形貌,塑性变形程度较高;微波烧结Cu_(60)Cr_(40)合金的显微组织逐渐转化为等轴晶,富Cu相和富Cr相分布较为均匀,烧结产生的孔隙显著减少。     

机械合金化制备β-FeSi2热电材料的研究

采用MA(Mechanical Alloying)法进行β-FeSi2热电材料的合成研究.以Fe粉(Fe>98%),Si粉(Si>99.9%)为原料,将Fe、Si 元素粉末按原子分数Fe33Si67混合,并将混合料放入高能星型球磨机进行长时间球磨.经不同的工艺进行机械合金化并取样,借助XRD、DSC等手段进行分析.研究结果表明在机械合金化大约20h以上开始形成ε-FeSi相,至机械合金化大约40h有β-FeSi2形成,随时间的延长β-FeSi2相增多.     

合金元素对机械合金化和放电等离子烧结Ti-Nb基合金显微组织的影响

β-Ti型结构的钛基材料在生物材料领域具有广泛的应用前景。本文采用机械合金化法和放电等离子烧结制备β-Ti型Ti-Nb基合金,研究不同Nb,Fe含量对合金显微组织及力学性能的影响。利用扫描电镜(SEM)、X射线衍射仪(XRD)和透射电镜(TEM)等手段分析合金的显微组织变化情况。结果表明:机械合金化过程中,粉末的平均粒度减小,当球磨时间超过60 h时粉末易发生团聚。当球磨转速为300 r/min,球料比为12:1,Ti和Nb的质量分数分别为64%和24%时,球磨100 h后制备的粉体材料中具有一定体积的非晶相。该粉末在1 000℃下通过放电等离子烧结(SPS)制备具有均匀细小的球状晶粒组织的Ti-Nb合金,其强度、伸长率和弹性模量分别为2 180MPa,6.7%和55 GPa。通过控制Nb,Fe的含量,可以促进β-Ti相形成,获得高强度和低杨氏模量的Ti-Nb合金。     

含氮ODS-310奥氏体钢粉末机械合金化的研究

以雾化预合金粉(成分为Fe-25Cr-20Ni)、Ti粉和纳米Y2O3为原料(成分配比为Fe-25Cr-20Ni+3%Ti+3%Y2O3),通过在氮气气氛中高能球磨的方式实现了原始粉末的机械合金化。在球磨转速、球料比、球磨气氛不变的情况下,研究了球磨时间对机械合金化效果、粉末微观形貌及氮含量的影响。球磨后的粉末在900、1 100和1 200℃下做退火处理,研究了退火温度对粉末析出相的影响。实验结果表明球磨50h后的氧化物弥散强化(oxide dispersionstrengthened,ODS)-310奥氏体钢粉末有非晶相生成。     

La_2O_3对微波烧结Cu_(20)Fe_(80)合金组织性能的影响

采用机械合金化和冷压微波烧结法制备了Cu_(20)Fe_(80)合金,研究了La_2O_3添加对Cu_(20)Fe_(80)合金组织性能的影响,利用扫描电子显微镜和X射线衍射仪等设备观察和分析Cu_(20)Fe_(80)合金组织形貌和相组成,并测定了合金的致密度和硬度。结果表明:Cu_(20)Fe_(80)合金粉体呈层片状,随La2O3质量分数的增加,合金粉体得到细化,机械合金化程度增强;Cu_(20)Fe_(80)合金粉体的冷压压坯组织呈层片状,随La_2O_3质量分数的增加,压坯致密程度和成型性提高;微波烧结后组织呈现层片状,随La_2O_3质量分数的增加,空隙先减少后增加,烧结组织致密度和硬度先提高后减小;综合分析,La_2O_3最佳添加量为0.2%。     

Phase Evolution and Mechanical Properties of Nano-TiO2 Dispersed Zr-Based Alloys by Mechanical Alloying and Conventional Sintering

The present study deals with the synthesis of 1.0 to 2.0 wt pct nano-TiO₂ dispersed Zr-based alloy with nominal compositions 45.0Zr-30.0Fe-20.0Ni-5.0Mo (alloy A), 44.0Zr-30.0 Fe-20.0Ni-5.0Mo-1.0TiO₂ (alloy B), 44.0Zr-30.0Fe-20.0Ni-4.5Mo-1.5TiO₂ (alloy C), and 44.0Zr-30.0Fe-20.0Ni-4.0Mo-2.0TiO₂ (alloy D) by mechanical alloying and consolidation of the milled powders using 1 GPa uniaxial pressure for 5 minutes and conventional sintering at 1673 K (1400 °C). The microstructural and phase evolution during each stage of milling and the consolidated products were studied by X-ray diffraction (XRD), scanning electron microscopy and transmission electron microscopy (TEM), and energy-dispersive spectroscopy. The particle size of the milled powder was also analyzed at systemic intervals during milling, and it showed a rapid decrease in particle size in the initial hours of milling. XRD analysis showed a fine crystallite size of 10 to 20 nm after 20 hours of milling and was confirmed by TEM. The recrystallization behavior of the milled powder was studied by differential scanning calorimetry. The hardness of the sintered Zr-based alloys was recorded in the range of 5.1 to 7.0 GPa, which is much higher than that of similar alloys, developed via the melting casting route.     

Fe3Al/TiC nanocomposite produced by mechanical alloying

Abstract

The aims of this work were to produce nanocrystalline powder by mechanical alloying of FeTi₂–Al–C powder mixture in a high energy ball mill and to study the phase transformation that took place during 20 h milling time. The microstructure and the phase transformations in the powder during milling were examined as a function of milling time and heat treatment. The phases of the product were evaluated by X-ray diffraction technique. The microstructural evolution during mechanical alloying was analysed using SEM. The results obtained showed that high energy ball milling, as performed in this work, led to the formation of a bcc phase identified as Fe(Al) solid solution and TiC_x after 2 h milling and nanocrytalline AlFe₃ and TiC_x after 5 h milling. The increase in the milling time resulted in the formation of AlFe₃C_x. By heat treatment of the body after 20 h milling at 1000°C, AlFe3C_x disappeared, showing that this phase is unstable.     

Phase transformation,structural evolution and mechanical property of nanostructured FeAl as a result of mechanical alloying

Objective of the work was to synthesize nanostructured FeAl alloy powder by mechanical alloying (MEA). The work concentrated on synthesis, characterization, structural and mechanical properties of the alloy. Nanostructured FeAl intermetallics were prepared directly by MEA in a high energy rate ball mill. Milling was performed under toluene solution to avoid contamination from the milling media and atmosphere. Mixtures of elemental Fe and Al were progressively transformed into a partially disordered solid solution with an average composition of Fe—50 at % Al. Phase transformation, structural changes, morphology, particle size measurement and chemical composition during MEA were investigated by X-ray diffraction (XRD), Scanning electron microscopy (SEM) and Energy dispersive X-ray spectroscopy (EDS) respectively. Vickers micro hardness (VMH) indentation tests were performed on the powders. XRD and SEM studies revealed the alloying of elemental powders as well as transition to nanostructured alloy, crystallite size of 18 nm was obtained after 28 hours of milling. Expansion/contraction in lattice parameter accompanied by reduction in crystallite size occurs during transition to nanostructured alloy. Longer milling duration introduces ordering in the alloyed powders as proved by the presence of superlattice reflection. Elemental and alloyed phase coexist while hardness increased during MEA.     

制备工艺对无钴AB5型贮氢合金的相结构和电化学性能的影响

用真空熔炼、快淬工艺以及球磨工艺制备稀土基无钴AB5型La（NiMnAlFe）5贮氢合金，用XRD测试了合金的相结构，并测试了不同制备工艺下合金的电化学性能。研究了制备工艺对无钴合金的相结构和电化学性能的影响。结果表明，由真空熔炼和快淬工艺制备的合金为CaCu5型单相结构，球磨合金由CaCu5型相和游离Ni相组成，并出现了非晶化趋势。快淬和球磨均使合金的放电容量降低，循环稳定性提高，但球磨工艺的影响更为显著，主要原因是球磨后合金中出现非晶化趋势。     

Microstructure and properties of CrMnFeCoNi high-entropy alloy prepared by mechanical alloying and spark plasma sintering

The equiatomic ratio CrMnFeCoNi high entropy alloy (HEA) was prepared by mechanical alloying (MA) and spark plasma sintering. This paper reports the behaviour of MA, the phase formation, microstructure and mechanical properties of CrMnFeCoNi HEA. With the increase of milling time, solid solution with single FCC phase was gradually formed. The single FCC phase remained as matrix after SPS at 1373?K and 50?MPa. Ultrafine-grained microstructure and good mechanical properties were obtained: At room temperature, the as-sintered bulks exhibit an excellent combination of high compressive strength (2390?MPa) and high fracture strain (47%).     

机械合金化制备铜碳合金增强铜-石墨复合材料

通过机械合金化制备Cu-5 ％C合金粉,并采用粉末冶金工艺制备铜碳合金增强铜-石墨复合材料即Cu-(Cu-5％C)-C,研究了制粉工艺和Cu-5％C合金粉对该复合材料显微组织及物理性能的影响.结果表明:随着球磨时间的增加,合金粉中铜的晶格常数先增大后减小,衍射峰强度不断降低,半高宽逐渐增大;球磨40 h后合金粉中的石墨衍射峰消失,再经400℃退火3h则球磨产生的次生相Cu2O衍射峰消失,且石墨峰未复现.当石墨含量为4％,合金碳含量不超过1.5％时,Cu-(Cu-5 ％C)-C复合材料试样的电导率均达61％ IACS以上;当合金碳含量为1.0％时,复合材料的屈服强度显著提高;当合金碳含量达到1.5％时,复合材料中的合金相严重分解,其增强效果大为减弱.