Effect of vacuum annealing on microstructure and mechanical properties of TA15 titanium alloy sheets

The mechanical properties, microstructures, and fractographs of TA15 sheets vacuum-annealed under different patterns were investigated. The results indicate that vacuum annealing significantly improves the mechanical properties of the sheets in comparison with those after ambient annealing. With increasing the annealing temperature, the phase boundaries and secondary a-phase increase, whereas the volume fraction of primary a-phase decreases, resulting in increased strength and decreased elongation A relatively fine secondary a-phase is obtained after double annealing. The desirable mechanical properties （i.e., ultimate tensile strength, yield strength, and elongation are 1070 MPa, 958 MPa, and 15%, respectively） are obtained through double annealing （（950 ℃/2 h, AC）＋（600 ℃/2 h, AC））. The fractographs obtained after tensile tests show that the deepest and largest dimples are formed in the specimen annealed at 850 ℃, which indicates that the best plasticity is obtained at this annealing temperature.

Effect of vacuum annealing on the characteristics of composite pellets containing DBSA-doped polyaniline and Fe nanoparticles

The DBSA-PANI-Fe composite powder with 50wt% of Fe nanoparticles was prepared by mechanically mixing the DBSA-doped polyaniline powder and Fe nanoparticles. The composite powder was compacted to pellets and the pellets were annealed in vacuum at 443,493,543, and 593 K for 60 and 120 min. The conductivity of the pellet increases markedly with increasing the annealing temperature up to 493 K, and then decreases with further increasing the annealing temperature. When the pellet was annealed at 493 K for 60 min, the increment of conductivity reaches a maximum value, and the conductivity is 2.6 times as large as that of the pellet unannealed. The conductivities of the pellets annealed under the conditions of 543 K/120 min, 593 K/60 min, and 593 K/120 min are lower than the conductivity of the pellet unannealed. For all the pellets, the variation in conductivity with temperature reveals that the charge transport mechanism can be considered to be 1-D variable-range-hopping （1-D VRH）. The composite pellet shows a magnetic hysteresis loop independent of the annealing condition. The saturation magnetization is about 5.4×10^4 emu/kg. The saturation field and the coercivity are estimated to be 4.38×10^5 and 3.06×10^4 A/m, respectively. The crystalline structure ofFe nanoparticles in the composites does not change with the annealing condition. The annealing condition cannot destroy the polymer backbones.

Interface microstructure and diffusion of vacuum annealed ceramic coating on superalloy GH202

In order to improve the wear resistance and high-temperature oxidation resistance of superalloy GH202, the ultrafine-grain ceramic coating containing nano-size nickel particles was obtained by flow coat method on the surface of GH202. The interface microstructure between ceramic coating and superalloy GH202 substrate during vacuum diffusion was studied. It is shown that Al2O3 oxide layer and (Ti, N) compound exist in the alloy substrate close to interface. During long time diffusion, nano-size nickel powders gradually congregate and grow up, and the confluent interface appears, which shows that the nano-size nickel powders have the effect of restraining the coating from failure.

XPS STUDY OF SUPERCONDUCTOR Ba_2YCu_3O_(7-δ) BY VACUUM ANNEALING

Discovery of the superconductivity in Ba-Y-Cu-O system above liquid nitrogen transition temperature has stimulated the extensive studies. The properties of superconducting material depend on the temperature and atmosphere during its sinter. In fact, the oxygen content in sample can be affected seriously by sintering and annealing procedure. The results of X-ray and neutron diffraction analysis indicate that the oxygen vacancy plays an important role in superconductor Ba-Y-Cu-O

Vacuum relaxation and annealing-induced enhancement of mobility of regioregular poly(3-hexylthiophene) field-effect transistors

In order to enhance the performance of regioregular poly（3-hexylthiophene） （RR-P3HT） field-effect transistors （FETs）, RR-P3HT FETs are prepared by the spin-coating method followed by vacuum placement and annealing. This paper reports that the crystal structure, the molecule interconnection, the surface morphology, and the charge carrier mobility of RR-P3HT films are affected by vacuum relaxation and annealing. The results reveal that the field-effect mobility of RR-P3HT FETs can reach 4.17×10^-2m^2/（V·s） by vacuum relaxation at room temperature due to an enhanced local self-organization. Furthermore, it reports that an appropriate annealing temperature can facilitate the crystal structure, the orientation and the interconnection of polymer molecules. These results show that the field-effect mobility of device annealed at 150 ℃ for 10 minutes in vacuum at atmosphere and followed by placement for 20 hours in vacuum at room temperature is enhanced dramatically to 9.00×10^-2m^2/（V·s）.

High Resolution Electron Microscopy Observations of Structural Changes in Iron Nitride Films Annealed in Vacuum

Iron-nitride films were prepared by reactive sputtering, and the effect of annealing treatment on the structures was investigated by means of in-situ electron microscopy and high resolution electron microscopy (HREM). As-deposited films were observed to be a mixed structure of a few ultrafine epsilon-Fe2-3N particles existing in the amorphous matrix. it was found that the structure-relaxation in the amorphous occurred at 473 K, and the ultrafine grains began to grow at the higher annealing temperatures. The transition of the amorphous to epsilon-Fe2-3N was almost completed at 673 K. It is considered that the formation of the ideal epsilon-Fe3N is originated from the ordering of the nitrogen atoms during the annealing in vacuum. On the other hand, gamma'-phase (Fe4N) was seen to precipitation of epsilon-phase at 723 K. Two possible modes are proposed in the precipitation of gamma'-phase, depending on the heating rate and crystallographic orientation relationships, i.e. [121](epsilon)//[001](gamma), (2(1) over bar0$)(epsilon)//(110)(gamma) and [100](epsilon)//[110](gamma), (001)(epsilon)//(111)(gamma). In addition, alpha-Fe particles were observed to form from the gamma'-phase at high temperatures. We assumed that these structural changes are due to the diffusion of nitrogen and iron atoms during the annealing, except for the case of the precipitation of the gamma'-phase as depicted above. The results obtained in this work are in a good agreement with the assumption.

Micro-properties of a type 316 Steel Annealed in Air and Vacuum

Micro-properties of the oxide scale and near-surface zone of a type 316 steel annealed in air and vacuum have been systematically investigated. Microstructures of the specimens have been examined using optical microscopy and scanning and transmission electron microscopy (TEM). Chemical compositions for the oxide scale and near surface zone were also analysed. The results obtained show that the oxide scale developed in vacuum exhibits a distinct structure from that developed in air. Comparing to the vacuum-developed scale, the air-developed scale possesses a more complicated structure and relatively poor adhesion to the matrix. TEM observations reveal a difference in the dislocation density in the vicinity of the free surface, near-surface zone and the core of the specimens examined.

Isolated Cobalt Nanoparticles Prepared on HOPG in Ultrahigh Vacuum Using Thermal Annealing

Cobalt nanoparticles on the surface of highly oriented pyrolytic graphite have been studied by atomic force microscopy. Thermal annealing in ultrahigh vacuum was used to change the size of cobalt nanoparticles and their surface distribution. The effect of two key parameters, annealing time and temperature, on the size and the surface distribution of nanoparticles has been studied. The dependence of the particle size on these parameters has been obtained. It has been shown that the main mechanism of the nanoparticle growth is Ostwald ripening.

Soft magnetic properties of amorphous Fe_(52)Co_(34)Hf_7B_6Cu_1 alloy treated by pulsed magnetic field and annealing

The crystallization, microstructure, and soft magnetic properties of Fe52Co34Hf7B6Cul alloy are studied. Amorphous Fe52Co34Hf7B6Cul alloys are first treated by a pulsed magnetic field with a medium frequency, and then annealed at 100 ℃-400 ℃ for 30 min in a vacuum. The rise in temperature during the treatment by a pulsed magnetic field is measured by a non-contact infrared thermometer. The soft magnetic properties of specimens are measured by a vibrating sample magnetometer （VSM）. The microstructure changes of specimens are observed by a MSssbauer spectroscopy and transmission electron microscope （TEM）. The results show the medium-frequency pulsating magnetic field will pro- mote nanocrystallization of the amorphous alloy with a lower temperature rise. The nanocrystalline phase is （α-Fe（Co） with bcc crystal structure, and the grain size is about 10 nm. After vacuum annealing at 100 ℃ for 30 min, scattering nanocrystalline phases become more uniform, the coercive force and the saturation magnetization of the specimens are 41.98 A/m and 185.15 emu/g.

Effects of thickness and annealing condition on magnetic properties and thermal stabilities of Ta/Nd/NdFeB/Nd/Ta sandwiched films

Ta/Nd/NdFeB/Nd/Ta sandwiched films are deposited by magnetron sputtering on Si（100） substrates,and subsequently annealed in vacuum at different temperatures for different time.It is found that both the thickness of NdFeB and Nd layer and the annealing condition can affect the magnetic properties of Ta/Nd/NdFeB/Nd/Ta films.Interestingly,the thickness and annealing temperature show the relevant behaviors that can affect the magnetic properties of the film.The high coercivity of 24.1 kOe（1 Oe = 79.5775 A/m） and remanence ratio（remanent magnetization/saturation magnetization）of 0.94 can be obtained in a Ta/Nd（250 nm）/NdFeB（600 nm）/Nd（250 nm）/Ta film annealed for 3 min at 1023 K.In addition,the thermal stability of the film is also linked to the thickness of NdFeB and Nd layer and the annealing temperature as well.The excellent thermal stability can be achieved in a Ta/Nd（250 nm）/NdFeB（600 nm）/Nd（250 nm）/Ta film annealed at1023 K.

整流罩紧固环故障件分析及专家判定法判定筛选

在硬度不合格故障件排查中,用视觉外观对比、体式显微镜对比、表面能谱和金相组织分析,对整流罩紧固环真空退火和未真空退火零件进行了对比分析,合格件显亮色,有金属光泽,故障件金属光泽暗淡。采用专家判定法,通过视觉外观差异检查判断,对整流罩紧固环待装配零件进行了筛选,从故障批零件中筛选出了硬度偏高不合格零件,筛选后整流罩紧固环滚压粘接100%合格,满足了产品加工需求。

基于模糊自整定PID算法的退火炉温度调节技术

由于未考虑到退火炉温度偏差值的影响,导致超调量较高,调节效果欠佳。为此,提出基于改进模糊自整定PID算法的真空退火炉温度动态调节技术。依据真空退火炉的工作机理,分析退火炉在工作中的温度变化曲线,采用双曲正切函数求取温度调节过程中的温度偏差值,从而对其动态温度进行设定,采用改进模糊自整定PID算法构造温度模糊控制器,通过对设计的温度模糊控制器内部控制参数进行优化,从而对控制器结构进行更新,并将退火炉的相关参数作为输入量,目标温度作为输出量,由此实现对退火炉温度的动态调节。实例应用结果显示,所提方法可以有效实现对真空退火炉温度的动态调节,且超调量较低,调节效果较好。

低阻高透过率ITO薄膜的制备与性能

研究了直流磁控溅射法制备的ＩＴＯ薄膜的光电特性与溅射工艺参数的关系以及退火处理对ＩＴＯ薄膜光电特性的影响。在低衬底温度、低溅射功率下获得了优质的ＩＴＯ薄膜，可见光透过率高于８５％，在厚度为１００ｎｍ时其方块电阻在１５０～２００Ω／□之间，并且ＩＴＯ薄膜的制备工艺完全与ＡＭＬＣＤ中ＴＦＴ器件的制作工艺兼容。

特型二氧化钒薄膜的制备及电阻温度系数的研究

采用真空蒸发真空退火的制备工艺,制备出了特定的VO2(B)型薄膜并给出了最佳制备条件,经X射线衍射(XRD)分析及电学参数测试,其电阻温度系数(TCR)值达到-3.4×10-2K-1,无相变和热滞现象.作者还讨论了薄膜电阻温度关系,及其电阻温度系数与晶粒大小、激活能等的关系.

基体偏压对电弧离子镀AlCrSiON涂层结构和热稳定性的影响

为研究基体偏压对AlCrSiON纳米复合涂层结构、力学性能和热稳定性的影响规律及机制,采用电弧离子镀技术在硬质合金基体上沉积AlCrSiON涂层。利用扫描电子显微镜（SEM）、X射线衍射仪（XRD）、透射电子显微镜（TEM）、纳米压痕仪（划痕仪）研究涂层组织结构和力学性能;通过真空退火试验研究涂层的高温稳定性。结果表明：AlCrSiON涂层为致密柱状晶结构,并主要由c-（Al,Cr）N和c-（Al,Cr）（O,N）两相组成,呈现出纳米复合结构。随着偏压的升高,涂层表面的颗粒数目和尺寸减少,组织结构更加致密;硬度和弹性模量均呈现出先增加后减小的趋势,当偏压为–80 V时分别达到最大值30.1 GPa和367.9 GPa。涂层具有良好的高温稳定性,不同偏压下沉积的AlCrSiON涂层经800~950℃热处理后均能够保持良好的结构稳定性及力学性能,但经1 100℃热处理后涂层发生相分解并引发组织结构变化,导致涂层硬度减小。

真空热处理对硫化锌薄膜光学与微结构特性的影响

针对电子束蒸发离子辅助沉积的硫化锌薄膜,研究了550℃以下真空热处理对其光学与微结构特性的影响。薄膜光学和微结构特性的测试分析表明:制备后薄膜为类立方结构的ZnS,在337.5nm波长处出现临界特性转折点,随着热处理温度的增加,转折波长两侧的消光系数变化规律相反,折射率和物理厚度呈现下降趋势,薄膜的禁带宽度逐渐增加;在红外波段的薄膜折射率与热处理温度的变化并不显著,在350℃下热处理时消光系数出现转折,主要是由晶粒变小的趋势所致;通过晶相分析,硫化锌薄膜经历了类立方结构到六方结构的转换,与禁带宽度的变化趋势基本一致。分析结果表明,光学特性变化的根本原因是薄膜的微结构特性变化。

金属Sn氧化薄膜的真空退火与原位XPS测量

本文研究了在真空退火过程中金属Sn氧化薄膜表面L元素Sn和O的化学性质．利用X射线光电子能谱（XPS）的表面分析方法，发现在金属Sn氧化薄膜的表面上存在大量的吸附氧粒子（O-和）提高真空退火温度，吸附氧粒子的数量增加；同时吸附氧粒子的负电性变弱．当退火温度低于350℃时，吸附氧粒子数量的增加是起因于SnO2→Sn2O3的转变；在这种情况下，可以观察到Sn2O3是相对稳定的金属Sn氧化物，继续提高退火温度，达到400℃时，Sn在金属Sn中的相对含量急剧增大，Sn在金属Sn中相对含量增加的原因与金属Sn的价态Sn3+→Sn0的转变相关在这个转变过程中伴随着O的释放和薄膜表面氧粒子的进一步堆积．与温度低于350℃时的退火条件相比，XPS的测量也发现，在400℃的退火温度下；SnO2相对于Sn2O3反而成为比较稳定的金属Sn氧化物．还讨论了金属Sn氧化薄膜表面上吸附氧粒子的吸附状态以及吸附状态与退火温度的关系．

大尺寸优质钒酸钇(YVO_4)双折射晶体生长

采用硝酸脱水合成的原料，异型大口径铱坩埚，近平界面生长技术以及真空增氧退火工艺，成功地生长出直径为３０～３５ｍｍ，长度为５０ｍｍ完整透明，无散射中心，无核芯的ＹＶＯ４单晶。

离子束辅助沉积和真空退火对硫化锌薄膜应力的影响

在硅基底上用电子束蒸发方法制备了硫化锌薄膜。通过XRD和薄膜应力测试仪研究了离子束辅助沉积和真空退火对硫化锌薄膜应力的影响规律。结果表明,未采用离子辅助技术制备的硫化锌薄膜为压应力,平均应力值为110.6 MPa,当采用离子束辅助工艺时硫化锌薄膜的压应力增加了62.3MPa。真空退火使硫化锌薄膜的平均应力大约降低了二分之一。硫化锌薄膜的微观结构变化是影响薄膜应力的主要因素。

反应磁控溅射法制备氧化钒薄膜

采用反应磁控溅射加真空退火分别在玻璃和Si(100)基底上制备氧化钒薄膜,利用X射线衍射和原子力显微镜分析其物相和表面形貌。结果表明:氧气体积分数低于15%时,玻璃上薄膜为低价钒氧化物,Si(100)上薄膜为V2O5(001)织构和V2O3(104)织构,高于20%时两基底上薄膜均为V2O5;玻璃上V2O5薄膜500℃下退火3h生成VO2,退火后薄膜粗糙度明显下降;Si(100)上V2O5薄膜500℃下退火2h生成V2O3(104)织构,退火后薄膜粗糙度变化不大。