球磨时间对机械合金化Al-8Ti合金组织的影响

采用机械合金化方法制备Ａｌ－Ｔｉ合金时，球磨时间影响粉体的粒度、结构和相组成，从而影响合金成型后的组织结构与性能。经过足够长时间球磨后，Ａｌ、Ｔｉ混合粉转变为单一Ａｌ（Ｔｉ）过饱和固溶体，且颗粒细小均匀；成型后可获得Ａｌ基体上弥散分布细小Ａｌ３Ｔｉ颗粒的Ａｌ－Ｔｉ合金。     

球磨时间对机械合金化Al—8Ti合金组织的影响

采用机械合金化方法制备Ａｌ－Ｔｉ合金时，球磨时间粉体的粒度、结构和相组成，从而影响合金成型后的组织结构与性能。经过足够长时间球磨后，Ａｌ、Ｔｉ混合粉转变为单一Ａｌ（Ｔｉ）过饱和固溶体，且颗粒细小均匀；成型后可获得Ａｌ基体上弥散分布细小Ａｌ３Ｔｉ颗粒的Ａｌ－Ｔｉ合金。     

Ti—Al混合粉末在机械合金化过程的固态相变研究

研究了Ｔｉ－Ａｌ混合粉末在机械合金化过程中的粉体粒度，显微组织形貌和晶体结构。结果表明，层片复合结构的形成，为通过原子间的短距离扩散而实现固态合金化提供了空间条件，而引入了大量空位的畸变的晶体结构，为固态相变提供了热力学条件和动力学条件。为固态相变进程是，Ａｌ原子向α－Ｔｉ晶格内扩散，首先形成α－Ｔｉ的过饱和固溶体，随后转变为Ｔｉ３Ａｌ金属间化合物。     

机械合金化过程中六方相晶格畸变特点的研究

通过分析球磨试样和球磨后退火试样的Ｘ射线衍射谱，研究了Ｔｉ，Ａｌ混合粉末机械合金化过程中六方相α－Ｔｉ和Ｔｉ３Ａｌ的晶格畸变特点。结果表明，六方相畸变特点为晶体常数减小和ｃ，ａ轴比值ｃ／ａ减小，其中α－Ｔｉ的（０１１１）面和Ｔｉ３Ａｌ的（２０２１）面原子错排最为严。讨论了位错滑移系统和空穴的引入与晶格畸变特点的联系。     

SiC_w／Al_2O_3－（Ti，W）C复相陶瓷的微观结构及其力学性能EI

本文对Ａｌ_２Ｏ_３（Ｔｉ，Ｗ）Ｃ和ＳｉＣｗ－Ａｌ_２Ｏ_３（Ｔｉ，Ｗ）Ｃ的力学性能进行了分析对比，研究了热压工艺、ＳｉＣ晶须含量、晶须分散效果和晶须／基体的复合情况等对Ａｌ_２Ｏ_３（Ｔｉ，Ｗ）Ｃ复相陶瓷力学性能的影响。从热膨胀系数失配角度分析和微观结构的观察证实，ＳｉＣ晶须及（Ｔｉ，Ｗ）Ｃ固溶体对改善Ａｌ_２Ｏ_３陶瓷力学性能的效果是显著的，ＳｉＣ_ｗ－Ａｌ_２Ｏ_３．（Ｔｉ，Ｗ）Ｃ陶瓷材料的增韧机制主要是裂纹偏转和裂纹桥接。     

SiC_w／Al_2O_3－（Ti，W）C复相陶瓷的微观结构及其力学性能

本文对Ａｌ_２Ｏ_３（Ｔｉ，Ｗ）Ｃ和ＳｉＣｗ－Ａｌ_２Ｏ_３（Ｔｉ，Ｗ）Ｃ的力学性能进行了分析对比，研究了热压工艺、ＳｉＣ晶须含量、晶须分散效果和晶须／基体的复合情况等对Ａｌ_２Ｏ_３（Ｔｉ，Ｗ）Ｃ复相陶瓷力学性能的影响。从热膨胀系数失配角度分析和微观结构的观察证实，ＳｉＣ晶须及（Ｔｉ，Ｗ）Ｃ固溶体对改善Ａｌ_２Ｏ_３陶瓷力学性能的效果是显著的，ＳｉＣ_ｗ－Ａｌ_２Ｏ_３．（Ｔｉ，Ｗ）Ｃ陶瓷材料的增韧机制主要是裂纹偏转和裂纹桥接。     

TiC／（Al_2O_3／Y－TZP）复相陶瓷的制备与性能

本文采用热压工艺制备ＴｉＣ和Ａｌ_２Ｏ_３共同补强Ｙ－ＴＺＰ基复相陶瓷，研究了复相陶瓷的相组成、力学性能及显微结构．发现复相陶瓷的高温强度得到显著提高，１０００℃时，组成为３０ｖｏｌ％ＴｉＣ－（２５ｖｏｌ％Ａｌ２Ｏ３／１．８Ｙ－ＴＺＰ）复相陶瓷抗弯强度高达６１４ＭＰａ．ＴｉＣ颗粒补强机制在高温下发挥了重要作用．     

机械合金化合成Al—Ti系纳米过饱和固溶体

利用ＸＲＤ，ＴＥＭ，硬度试验研究了Ａｌ－Ｔｉ系的机械合金化（ＭＡ）过程．经４０ｈ球磨后，Ａｌ－１５ａｔ．－％Ｔｉ形成了Ａｌ（Ｔｉ）的过饱和固溶体，Ａｌ－１０ａｔ．－％Ｔｉ除形成Ａｌ（Ｔｉ）外，还产生了少量的ｆｃｃ结构的新相．而Ａｌ－５ａｔ．－％Ｔｉ在球磨１２０ｈ后也未能形成完全的Ａｌ（Ｔｉ），但有ｆｃｃ结构相的形成，这种特殊的固溶行为可以用溶质原子在纳米晶晶界快扩散解释     

TiAl基合金包套锻复合热机械处理工艺的研究

针对用于ＴｉＡｌ基合金的常规热机械处理的局限性，提出了包套锻复合热机械处理新工艺。详细地研究了此项新工艺的工艺参数对Ｔｉ－３３Ａｌ－３Ｃｒ－０．５Ｍｏ合金显微组织及锻坯表观质量的影响。     

Ti_3Al－Nb合金显微组织的研究

用透射电镜和ｘ射线能谱分析研究了Ｔｉ_３Ａｌ－Ｎｂ合金（Ｔｉ－２４Ａｌ－１４Ｎｂ－３Ｖ－０．５Ｍｏ）不同热处理状态下的组织结构。结果表明,Ｔｉ_３Ａｌ－Ｎｂ合金经α_２＋β两相区固溶１ｈ水冷处理以及经８５０℃时效２４ｈ空冷处理时,其显微组织由α２相、β２相和″０″相组成;低温区固溶处理,降低冷却速度以及固溶化时效处理均会有针状α２相析出,随着固溶温度的降低,α２相和″０″相的数量逐渐增多。     

Thermal stability and mechanical properties of mechanically alloyed Al-10Ti alloy

The mechanical properties of Al-10Ti alloy prepared by mechanical alloying and subsequent hot hydrostatic extrusion were evaluated at room and elevated temperatures. Transmission electron microscopy was used to characterize the microstructural changes of this alloy on heat treatment at 500 °C for various times. The results show that the mechanically alloyed Al-10Ti has high strength and high thermal stability at elevated temperature. The strength and stability of this alloy are attributed to its fine grain size and to the high volume fraction of small Al₃Ti intermetallic compounds dispersed in the aluminium matrix. After 50 h annealing at 500 °C, no serious coarsening of either the Al₃Ti dispersoids or the grains was observed.     

Sintering behavior of mechanically alloyed Ti-48Al-2Nb aluminides

Ti-Al intermetallics have been produced using mechanical alloying technique. A composition of Ti-48Al-2Nb at % powders was mechanically alloyed for various durations of 20, 40, 60, 80 and 100 h. At the early stages of milling, a Ti (Al) solid solution is formed, on further milling the formation of amorphous phase occurs. Traces of TiAl and Ti₃Al were formed with major Ti and Al phases after milling at 40 h and beyond. When further milled, phases of intermetallic compounds like TiAl and Ti₃Al were formed after 80 hours of milling and they also found in 100 h milled powders. The powders milled for different durations were sintered at 785°C in vacuum. The mechanically alloyed powders as well as the sintered compacts were characterized by XRD, FESEM and DTA to determine the phases, crystallite size, microstructures and the influence of sintering over mechanical alloying.     

Synthesis of nanocrystallite by mechanical alloying and in situ observation of their combustion phase transformation in Al3Ti

Elemental powders of stoichiometric Al₃Ti were mechanically alloyed (MA) in order to investigate the phase formation during the milling process. Furthermore the stability of MA powders were studied under transmission electron microscopy (TEM). The results indicate that a supersaturated Al(Ti) solid solution with nanocrystalline size has been formed after mechanical alloying for 360 ks in consuming the elemental powders of Al and Ti and no further phase transformation can be detected upon longer milling. The MA powders are unstable being irradiated by electron beams under the TEM observation, exothermically forming various intermetallic compounds. The combustion phase transformation processes and products are depending on the time of mechanical alloying. The structural changes and phase transformations during both mechanical alloying process and annealing process were also characterized by using X-ray diffraction measuring.     

粉末冶金TiVNbTa难熔高熵合金的组织和力学性能

将机械合金化(MA)与放电等离子烧结(SPS)相结合制备了难熔TiVNbTa高熵合金,研究了这种合金的机械合金化过程、相组成和显微组织,以及烧结温度和O、N含量对其力学性能的影响。结果表明:机械合金化后高熵合金粉末为BCC结构,放电等离子烧结成的块体高熵合金由BCC基体和FCC析出相组成,其析出相为TiN+TiC+TiO的复合物。烧结温度为1100℃的高熵合金具有良好的综合力学性能,压缩屈服强度达到1506.3 MPa,塑性应变为33.2%。随着烧结温度的提高,合金发生了从准脆性到塑性再到脆性断裂的转变。O和N含量的提高对高熵合金强度的影响较小,但是使其塑性显著降低。     

Microstructure and Mechanical Properties of Al-4.9Ni-4.9Ti Alloy Prepared by Mechanical Alloying

Mechanically alloyed Al-4.9Ni-4.9Ti powders were prepared by milling mixed aluminium, titanium and nickel powders, and then consolidated by hot hydrostatic extrusion. The microstructures of milled powders and extruded bars were characterized by X-ray diffraction and transmission eIectron microscopy observation. The results show that mechanical alloying and consolidating processes have great effects on the microstructures and mechanical properties of extruded materials. Polycrystalline materials having an ultrafine grain size may be prepared by mechanical alloying. The strength and thermal stability are improved with the increasing of processing time of mechanical alloying, since grain size decreases and volume fraction of dispersoids increases as milling time increased     

Fabrication of Ti–Nb–Ag alloy via powder metallurgy for biomedical applications

Ti and some of its alloys are widely used as orthopedic implants. In the present study, Ti–26Nb–5Ag alloys were prepared by mechanical alloying followed by vacuum furnace sintering or spark plasma sintering (SPS). The microstructure and mechanical properties of the Ti–Nb–Ag alloys were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM) combined with energy-dispersive X-ray spectroscopy (EDX), compressive and micro-hardness tests. The effect of different sintering methods on the microstructure and properties of Ti–Nb–Ag alloy was discussed. The results showed that the titanium alloy sintered by vacuum furnace exhibited a microstructure consisting of α, β and a small amount of α″ martensite phase; whilst the SPS sintered alloy exhibited a microstructure consisting of α, β and a small amount of α″ martensite phase, as well as a nanostructured Ag homogeneously distributed at the boundaries of the β phases. The Ti–Nb–Ag alloy sintered by SPS possessed fracture strength nearly 3 times of the alloy sintered by vacuum furnace.     

Ti对金红石型药芯焊丝熔敷金属组织性能影响

以金红石型药芯焊丝为基础,通过在焊丝中加入不同含量的钛铁,研究了Ti对熔敷金属组织及力学性能的影响。结果表明,随焊丝钛含量的增加,脱氧方式从Ti、Si、Mn联合脱氧逐渐转为以Ti脱氧为主,且熔敷金属中夹杂物的Ti含量逐渐增大,同时熔敷金属中合金元素含量增加,屈服强度逐渐趋近抗拉强度,塑性变差。组织分析发现,以复合氧化物形式存在的化合钛对针状铁素体的形成有促进作用,以合金元素形式存在的固溶钛对针状铁素体的形成有抑制作用。     

不同合金元素的建筑用耐火钢性能之间的对比

本实验以含Mo、Nb、Ti与V微合金元素的建筑用耐火钢为研究对象，通过对比合金元素含量不同的建筑用耐火钢的力学性能和显微组织，研究了合金元素Mo、Nb、Ti与V对建筑用耐火钢高温屈服强度的影响。实验结果表明Mo、Nb的复合添加是提高耐火钢高温屈服强度的有效方法。     

机械诱发自蔓延反应合成Ti(C,N)粉体的固态相变

利用机械合金化方法以Ti粉、石墨粉和高纯氮气为原料,制备出Ti(C,N)粉体。利用X射线衍射、正电子湮灭寿命谱、X光电子能谱以及扫描电镜等分析手段,研究了球磨过程中混合粉的相组成、缺陷类型、粉体形貌及尺寸的变化。实验结果表明:Ti(C,N)粉体的合成遵循机械诱发自蔓延反应机制,中间相TiN的出现是导致反应进行的关键阶段。     

Characterization of mechanically alloyed ternary Fe–Ti–Al powders

The effects of Ti-substitution for Fe in the Fe₃Al system on the mechanical alloying process were investigated. For this purpose, blended elemental powders with the following nominal compositions (at.%): Fe₇₅Al₂₅, Fe₇₀Ti₅Al₂₅, Fe₆₅Ti₁₀Al₂₅, Fe₆₀Ti₁₅Al₂₅, were mechanically alloyed in a high energy attritor-type ball milling system for up to 100 h. The structural evolution in these powders was characterized by scanning electron microscopy, differential thermal analysis and X-ray diffraction techniques. It was found that elemental powders were progressively transformed into nanocrystalline solid solutions during mechanical alloying. The addition of Ti in the powders shortened the milling time for solid solution formation. With increasing Ti content, the grain size of the solid solutions decreased, but the lattice parameter increased. Upon heating, the milled powders were transformed into ordered (Fe,Ti)₃Al intermetallic compounds in an extended range of temperature (from 350 to 500°C). Ti addition enhanced the occurrence of DO₃ ordering in heated powders.