球磨时间对TiB_2-Ni(Al)复合粉末组织结构影响研究

在不同球磨时间条件下,采用机械球磨方法制备TiB_2-Ni(Al)复合粉末,其中Ni粉和Al粉的物质的量比为1∶1,TiB_2陶瓷相含量为40%(体积分数)。采用扫描电子显微镜(SEM)以及X射线衍射仪(XRD)分析球磨后粉末的显微组织结构及物相,研究不同球磨时间对制备TiB_2-Ni(Al)复合粉末物相演变、组织结构的影响。研究结果表明,随着球磨时间的延长,延性金属Ni和Al变形程度逐渐增大,粉末中呈现Ni/Al交替混合组织结构,此种结构有利于金属在球磨过程中扩散形成Ni(Al)固溶体,且逐渐细化的TiB_2相嵌入至金属Ni和Al颗粒中。通过物相分析发现,随着球磨时间的延长,Al衍射峰强度逐渐降低,并发现在球磨时间为36h时形成Ni(Al)固溶体。     

机械球磨Al-64wt.%Ti混合粉末的微观结构和热稳定性研究

本文研究了机械球磨方法制备的Al-64wt.%Ti混合粉末的微观结构和热稳定性.X射线衍射谱(XRD)研究结果表明,经过140h的球磨作用,形成了hcp相的亚稳态Ti(Al)超饱和固溶体;然后对粉末压坯进行固态反应烧结,最终的平衡产物是AlTi和Ti3Al,并用Miedema模型计算并比较了各竞争相的热力学结果..     

机械合金化法制备电动汽车电机用Fe-Si-Al合金粉

利用机械合金化法制备电动汽车电机用Fe-Si-Al合金磁粉;采用X射线衍射分析和扫描电子显微镜分别表征机械合金化过程中合金粉体的相结构和形貌,采用热分析对合金粉体的稳定性进行分析。结果表明:按照(FeSi)_(75)Al_(25)的原子比进行配料合金粉体,球磨10 h生成纳米晶α-Fe(Al,Si)固溶体,为体心立方晶体结构,粒径为1~20μm;球磨15 h,颗粒不断细化,晶粒粒径可达30 nm;(FeSi)_(75)Al_(25)磁粉在机械合金化过程中形成了具有典型层状结构且表面各种元素均匀分布的合金粉末包覆薄膜,无非晶相生成。     

氢化钛粉低温真空反应制备TiAl合金粉的研究

以平均粒径为46μm的氢化钛粉和平均粒径为6~7μm的铝粉为原料,经过低温高真空加热反应制备TiAl合金粉。研究了不同温度和保温时间后TiH2、Al粉合金化程度,用X射线衍射仪(XRD)分析其物相组成,扫描电子显微镜(SEM)观察其形貌特征。实验结果表明,高能球磨1h的TiH2、Al粉在500℃保温2h几乎可以将氢化钛中的氢除去,在750℃保温3h能够制得高纯度的TiAl合金粉,合金粉的平均粒径为20μm左右,合金粉颗粒呈不规则形状。     

球磨方式对制备(Ti,15W,5Mo,0.2V)(CN)-20Ni复合粉相结构的影响

利用X衍射仪研究了滚筒球磨和高能球磨后的混合料经碳热还原氮化制备(Ti,15W,5Mo,0.2V)(CN)-20Ni复合粉工艺过程中的物相演变.结果表明,普通滚筒球磨混合方式下的混合体系遵循TiO2→Ti3O5→Ti(ON)→Ti(CN)的相转变规律;而高能球磨混合方式下混合料的衍射峰普遍宽化,物料细化,活性提高,其中以高能球磨干混的效果最佳,其在1200℃即可获得无杂相的(Ti,15W,5Mo,0.2V)(CN)-20Ni复合粉,且反应过程未出现Ti(ON)中间相;另外在不同球磨方式下,随着Ti(CN)的形成,均有大量W、Mo、V等原子从Ni固溶体相中析出,并扩散进入Ti(CN)的晶格形成(Ti,W,Mo,V)(CN)固溶体.     

退火温度对Ti53.5Ni22.8Cu23.7合金快速凝固条带组织的影响

采用快速凝固法制备了Ti53.5Ni22.8Cu23.7合金薄带,对快速凝固合金条带在不同温度下退火热处理态的微观结构进行了X射线衍射和TEM分析.结果表明, 在450℃退火处理时,合金组织为B19、B2和条状析出物共存,条状析出物与基体呈共格关系,宽约为10～15nm;500℃退火以后形成纳米多晶B19和单晶B19的混合组织;Ti2(Ni Cu)析出物在高于550℃以上温度退火时形成,其晶粒尺寸随温度升高长大,板条宽由30～50nm变化到200～300nm;在650℃退火态下,Ti2(Ni Cu)晶粒进一步长大并影响马氏体的形貌,局部区域高密度晶界相互叠加形成莫尔条纹.     

机械合金化制备Ag-Cu-Sn钎料的组织和热稳定性

研究了机械合金化制备Ag-Cu-Sn三元体系形成过饱和固溶体的可能性,并对所得到的非平衡球磨产物的组织结构、热稳定性及其铺展重熔后的金相组织进行了表征。结果表明,通过控制球磨工艺和第三组元含量,可得到以过饱和固溶体为主要组成相的钎料合金粉,减少或细化脆性金属间化合物相。真空退火时,富银固溶体相较稳定,富铜固溶体相易于分解生成Cu_3Sn,银锡化合物可分解形成Ag基固溶体和富锡相,铜锡化合物的分解产物则为多种中间相,随退火温度的升高,转变顺序逐渐向铜锡原子比例增大的方向进行。以过饱和固溶体为主要组成相的钎料合金粉在重熔后虽然仍存在金属间化合物相,但金相组织明显细化。     

电子束沉积TiAl合金的微观形貌及组织结构稳定性

利用大功率电子束物理气相沉积设备,采用单靶蒸镀方法制备厚度为0.3mm的自由态TiAl合金板,并对制备态样品进行不同温度(650~950℃)的真空退火处理。借助X射线衍射仪、扫描电子显微镜及透射电子显微镜分析退火处理对相组成及微观组织结构的影响。结果表明:Ti,Al元素饱和蒸气压的差异导致富Ti成分区和富Al成分区沿板材截面呈现交替变化,其组成相为α_2-Ti_3Al,γ-TiAl和τ-TiAl_2;在650~950℃温度区间退火24h后,由于Al向Ti中扩散,呈现明显的界面融混和晶粒粗化,导致有序相含量的降低,其层状结构的退化受到孔洞形成、晶粒长大以及层间吞噬的影响。     

非晶Ti-Al储氢电极合金的制备及其电化学性能

采用真空感应悬浮熔炼法制备了Ti3Al合金,将合金粉碎后与Ni粉进行机械球磨,从而制得非晶态Ti-Al储氢电极合金。采用X射线衍射(XRD)、扫描电子显微镜(SEM)、电化学测试等方法研究了Ti-Al合金的微结构和电化学性能。XRD分析表明,未添加Ni粉球磨后,Ti3Al合金不发生非晶态转变,而添加Ni粉球磨后,Ti3Al合金由晶态转变为非晶态。电化学测试表明未添加Ni粉的Ti3Al合金最大放电容量仅为100.7mA·h·g-1;当添加Ni粉与合金进行球磨之后,随着Ni粉添加量的增加,合金最大放电容量先增加后减小;当Ni粉添加量为200wt%时,合金最大放电容量达到最大值476.7mA·h·g-1。对Ti3Al+200wt%Ni合金的进一步研究表明,随着球磨时间的增加,其最大放电容量先增加后减小。总之,Ni促进了Ti-Al合金的非晶转变,改善了合金的电化学性能,Ni粉的添加量和球磨时间对合金的电化学性能有显著影响。     

高能球磨法制备Fe_3Si合金粉末

采用高能球磨法研究了原子配比Fe75Si25的混合粉末在不同的球磨条件下的机械合金化,用X射线衍射(XRD)仪、扫描电子显微镜(SEM)表征样品的物相、晶体结构、晶粒尺寸和点阵常数,分析了Fe75Si25粉末的机械合金化机理。研究表明,球磨时间、球料比和球磨机转速对机械合金化(MA)进程有重要影响。MA 55h后可达到完全合金化,Si溶入Fe中形成α-Fe(Si)饱和固溶体,晶粒尺寸减小至7～8nm。     

TiNi Shape Memory Alloy Foams Synthesized by Spacer Sintering and their Properties

Titanium （Ti） and nickel （Ni） elemental powders were blended by ball milling and the ball milled powders were employed to fabricate TiNi shape memory alloy （SMA） foams by spacer sintering. Effect of ball milling time on phase constitutes of the sintered TiNi alloy foams was studied by X-ray diffraction （XRD） analysis. Scanning electron microscopy （SEM） was used to characterize the porous structure, and compressive tests were carried out to evaluate the mechanical properties of＇the foams. Results indicate that porosities of the TiNi alloy foams can be controlled by using the spacer sintering method, and the porosities show a significant effect on the mechanical properties and shape memory effect （SME）.     

Microstructure Evolution of Ti/BN Powder Blend during Ball Milling and Heat Treatment

Ball milled Ti/BN composite powder was prepared by high energy ball milling for 40 h, using Ti and BN (the molar ratio of Ti/BN is 3:2) as starting materials. The as-milled composite powder consists of TiN, Ti and amorphous phase. TiN formed while the milled powder was annealed at 400℃. The heat treatment at 700℃ led to the formation of TiB2 and TiB. The nanocrystalline Ti and amorphous phase converted to TiN and TiB2 when the powder was heated to 1300℃.     

Mechanochemical synthesis and heating-induced transformations of a high-entropy Cr-Fe-Co-Ni-Al-Ti alloy

An amorphous-crystalline two-phase (amorphous phase + BCC solid solution) powder alloy has been produced by mechanochemical synthesis (MS): by grinding an equiatomic mixture of Cr, Fe, Co, Ni, Al, and Ti metals in a Fritsch (P-7) ball mill at a powder-to-ball weight ratio of 1: 8. Using X-ray diffraction, X-ray microanalysis, and scanning electron microscopy, we have determined the sequence of reaction steps during milling of the mixture. In the early stages of milling (2 h), we observed the formation of an ordered phase (B2), Al + Ni → NiAl, and the Co_HCP → Co_FCC polymorphic transformation. Milling for 3 h led to the formation of a BCC solid solution. Further milling produced an amorphous phase (AP). In the range 6–25 h of milling, the percentage of the AP increased and that of the BCC solid solution decreased. The phase transformations induced by heating the alloy to 1200°C after MS have identified using differential thermal analysis and X-ray diffraction: \(MS (FCC + AP)\xrightarrow{{450^ \circ C}}(B2)\xrightarrow{{650^ \circ C}}(L2_1 + BCC)\xrightarrow{{850^ \circ C}}L2_1 + \sigma - phase\) (FeCr structure). Prolonged milling has been shown to stabilize the metastable BCC solid solution at temperatures of ?650°C.     

Synthesis of FeNiCoTi Powder Alloy by Mechanical Alloying and Investigation of Magnetic and Shape Memory Properties

FeNiCo base powder alloy with nominal composition Fe-27Ni-17Co-4Ti (wt%) was prepared from elemental powders by mechanical alloying. The structure of milled powders was characterized by XRD and SEM. The effect of nanosize structure on magnetic properties and shape memory behavior was studied using VSM and DSC. After milling for 240 minutes by high energy vibrational ball mill under argon atmosphere, supersaturated solid solution formed with mean crystallite size of ??20?nm. Results of VSM examinations showed that by milling for 240 minutes saturation magnetization and intrinsic coercivity reached 304 emu/gr and 21 Oe, respectively. XRD analyses made it clear that transformation from BCC to FCC phase has occurred after annealing supersaturated milled powder at 650 °C for 60?minutes. DSC curves indicated that martensite transformation in this alloy was suppressed due to refinement of the microstructure.     

Synthesis and Characterization of Nanocrystalline Ni-Ti and Ni-Cr Powders by Mechanical Alloying

Nanocrystalline powders in the Ni-Ti and Ni-Cr systems were prepared by mechanical alloying (MA) of elemental crystalline powders in an inert atmosphere. The microstructure of the mechanically alloyed powders were characterized by XRD and TEM. The ball-milling process results in a drastic decrease of the crystallite size to the nanometer scale. X-ray diffraction analysis reveals that in the Ni-Cr system, no diffraction peaks from NiCr compound were observed even after 20 h of ball milling; while the lattice parameter of Ni increased with the milling time. In the Ni-Ti system, amorphous alloy was formed. Crystalline intermetallic compounds were obtained by post heat treatment of the amorphous alloy.The crystallization temperature of the amorphous NiTi alloy was obtained be DSC measurement.     

机械合金化制备FeSiAl合金粉末的研究

采用机械合金化的方法制备了FeSiAl合金粉末样品。以硅钢粉和铝粉为原料,按摩尔分数Fe3Si0.4Al0.6配比,研究其机械合金化过程,并对机械合金化的机制进行探讨。用激光粒度仪、X射线衍射(XRD)和扫描电子显微镜分析材料的粒度、形貌和结构。研究表明,Fe3Si0.4Al0.6混合粉末球磨30h后,粉末粒径可达18μm;Fe3Si0.4Al0.6混合粉末经高能球磨20h后,形成具有bcc结构的α固溶体;球磨继续进行,合金化的粉末和晶粒不断细化。     

热处理对网状结构TiB_W/Ti60复合材料组织与性能的影响

使用大尺寸球形Ti60钛合金粉与细小TiB2粉,通过低能球磨与反应热压烧结,成功制备了增强相呈网状分布的TiB晶须增强Ti60合金基(TiB_W/Ti60)复合材料。对TiB_W/Ti60复合材料进行热处理,以改善其组织结构与力学性能。结果表明:随着固溶温度的升高,TiB_W/Ti60复合材料基体中初生α相(密排六方相)含量减少,相应地转变β组织(α′(马氏体)+残留β相(体心立方相))含量增加,TiB_W/Ti60复合材料的抗拉强度升高,塑性降低;经过1 100℃/1h固溶处理之后,TiB_W/Ti60复合材料的室温抗拉强度为1 470 MPa,延伸率为1.9%。经过时效处理后,转变β组织中的α′相分解成细小α+β相。经过1 100℃/1h固溶+600℃/8h时效处理后TiB_W/Ti60复合材料的硬度达到HV538,抗拉强度达到1 552 MPa,延伸率为1.5%,经过1 000℃/1h固溶+600℃/8h时效处理,其抗拉强度达到1 460 MPa,延伸率为2.2%。     

反应球磨钛与尿素制备氮化钛的反应机理研究

将Ti粉与尿素在室温下进行反应球磨制备了TiN粉末,对球磨不同时间后的粉末进行XRD分析,采用TG-FTIR技术分析了尿素的分解温度与产物,利用TEM及EELS观察和分析了球磨70h粉末的微观形貌、结构及成分. 结果发现,球磨70h合成了纳米TiN粉末,晶粒度为6~7nm,Ti/N原子比约为1.0∶0.6. 经800℃,5h真空退火处理后粉末的XRD谱图表明粉末组成为单相TiN. 在反应球磨过程中,Ti与尿素的分解产物NH₃与HNCO发生反应形成TiN,随球磨时间延长,Ti的缺陷能增大、活性增加,N在Ti中的扩散激活能减小,在球磨作用下N的扩散距离变短,TiN的含量逐渐增加形成晶核并逐渐长大形成纳米晶.     

Thermodynamic analysis of NiTi formation by mechanical alloying

Disordered B2-NiTi intermetallic phase was produced from a mixture of Ni and Ti powders by mechanical alloying (MA). X-ray technique was used for phase analysis. The results indicated that Ni(Ti) solid solution can be formed earlier and changed to disordered B2-NiTi intermetallic phase after 60 h of MA. A thermodynamic analysis of the process was then carried out using Miedema model. The results showed that there is a thermodynamic driving force in Ni–Ti binary to form solid solution at all compositions and amorphous phase in the composition range X_Ni: 0.05–0.95 where X_Ni is mole fraction of Ni. However, the stable phase which has the minimal Gibbs free energy is solid solution compared to amorphous phase at all compositions. The results of MA were compared with thermodynamic analysis and it was indicated that the product of MA is the most stable phase in Ni–Ti binary system.     

球磨Zr7Ni10合金提高Zr基电极合金的电化学性能

为了提高合金的放电容量和高倍率放电性能，通过球磨Zr7Ni10合金对Zr0．5Ti0．5Mn0．7V0．2Co0．1Ni1．2合金表面进行改性，并研究了不同Zr，Ni10量和球磨时间对合金的相结构和电化学性能的影响。当采用8％（质量分数）Zr，Ni10进行球磨1h后，合金仍保持晶态，在50mAh／g电流条件下经过9次循环达到最大放电容量266mAh／g，比未球磨合金提高了约20％，而且在300mA／g电流条件下仍能保持最大放电容量的85%。随着球磨时间的增加，合金逐渐转为非晶态，合金的放电容量也迅速降低。非晶化合金在800℃进行热处理后大部分重新晶化，经过22次循环达到最大放电容量200mAh／g。