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1.
通过同步辐射小角度x射线散射方法(SAXS),研究了三种Al_Zn_ Mg_Cu合金沉淀析出过程显微结构参数(析出相尺寸和体积分数),随时效温度和时效时间 的演化,同时分析了Zn含量对合金沉淀析出过程的影响.结果表明,三种合金(A,B,C) 在实验条件下析出相均属于纳米尺度,析出相的最大体积分数随Zn含量的增加而增加,最大体积分数分别为0.023—0.028,0.052—0.054和0.04.在一定时效温度下,体积分数随时效时间的变化规律,符合析出相的形核、核长大和粗化动力学过程.
关键词:
小角度x射线散射
Al_Zn_Mg_Cu合金
时效
析出相尺寸
析出相体积分数 相似文献
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应用小角x射线散射技术分析了Al-Zn-Mg-Cu-Li合金在130,150和160℃温度时效24 h析出粒子的微结构参数的变化情况. 粒子的半径随着时效温度的增高而增加,它的比内表面积和体积百分数随着时效温度的增高而减小. 对Porod曲线q3J(q)-q2的分析表明,析出粒子与基体之间有明显的界面.
关键词:
小角x射线散射
Al-Zn-Mg-Cu-Li合金
时效
析出粒子 相似文献
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本文研究了Ni-14.5Cr-1.5Si(wt%)合金淬火后时效发生的无序向有序转变对合金电阻率、对铂热电势、比热的影响。结果表明:电阻率显著增加,热电势、比热增加很小。X射线衍射分析表明,这是由于Ni2Si化合物型δ第二相的形成所致。
关键词: 相似文献
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本文研究了在相同退火热处理条件下,不同析出相含量的两种铝镁合金5456和5052在不同加载应变率下的P-LC效应. 结果表明析出相对两种材料的P-LC效应有明显影响,并且析出相含量的不同所产生的影响不同. 此外,析出相含量较少的5052合金的溶质原子的扩散方式是管扩散,而析出相含量较多的5456合金不再局限于管扩散的方式,而是更为复杂.
关键词:
Portevin-Le Chatelier effect
动态应变时效
铝镁合金 相似文献
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《物理学报》2017,(2)
采用差示扫描量热法、X射线衍射及透射电子显微镜研究了固溶和固溶一冷轧Ag-7wt.%Cu合金在时效过程中富Cu相的析出动力学和形貌特征,同时结合电阻率和显微硬度的测量,定量对比了固溶和固溶一冷轧Ag-7wt.%Cu合金时效过程中富Cu相对电阻率和硬度的影响及其机理.研究结果表明:固溶样品中富Cu相反应温度为300℃-350℃,析出激活能为(111±1.6)kJ/mol;而固溶一冷轧样品中由于形变能的存在,富Cu相温度降低为290℃-330℃,析出激活能升高为(128±12)kJ/mol.XRD结果证实富Cu相的析出过程与时效温度有关.固溶和固溶一冷轧合金在450℃时效后均能观察到球状的富Cu相,富Cu相的析出和溶解过程对电阻率和显微硬度有显著影响.当时效温度低于450℃时,随时效温度的提高,固溶一时效样品的电阻率降低,显微硬度增加:而固溶一冷轧一时效样品的电阻率和显微硬度均逐渐降低.显微硬度除了受富Cu相的影响外,还受到位错和形变孪晶的影响.当时效温度高于450℃时,两种样品的电阻率增大,而显微硬度降低. 相似文献
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本文以 Fe59.5Ni28Al11.5Ta1 形状记忆合金为研究对象, 采用金相显微镜、X 射线衍射仪、扫描电镜、能谱仪和压力试验机等研究了轧制后不同时 效时间处理对该合金组织结构和性能的影响. 结果表明, 随着时效的进行, γ’ 相和 β’ 相的相继析出, 强化了奥氏体基体. 综合伪弹性曲线看出, 随着时效时间的增加, 600 ℃时效态合金的应力诱发马氏体临界应力先减小后增大, 合金的抗压强度、可恢复的应变和硬度都先增大后减小, 合金的残余应变则先减小后增大, 时效时间为 60 h 时, 合金的抗压强度最大, 到达1306 MPa, 此时合金的可恢复形变最大, 达到14.9%, 合金的硬度也最大, 合金的残余应变相对最小. 但随着时效时间的延长, 合金的最大应变逐渐减小, 合金塑性逐渐减小. Fe59.5Ni28Al11.5Ta1 形状记忆合金的性能与沉淀相的颗粒大小、分布、体积分数等因素有关.
关键词:
59.5Ni28Al11.5Ta1')" href="#">Fe59.5Ni28Al11.5Ta1
时效处理
伪弹性
硬度 相似文献
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[001] single-crystal specimens of the superalloys CMSX-4 and CMSX-10 were tested for creep at 1100°C under tensile stresses between 105 and 135?MPa, where they show pronounced steady creep. The deformed superalloys were analysed by density measurements, scanning electron microscopy and transmission electron microscopy which supplied information about porosity growth, evolution of the γ–γ′ microstructure, dislocation mobility and reactions during creep deformation. It is shown that, under the testing conditions used, steady creep strain mostly results from transverse glide–climb of (a/2) ?011? interfacial dislocations. A by-product of the interfacial glide–climb are vacancies which diffuse along the interfaces to growing pores or to a ?100? edge dislocations climbing in the γ′ phase. Climb of a ?100? dislocations in the γ′ phase is a recovery mechanism which reduces the constraining of the γ phase by the γ′ phase, thus enabling further glide of (a/2) ?011? dislocations in the matrix. Moreover the γ′ dislocations act as vacancy sinks facilitating interfacial glide–climb. The creep rate increases when the γ–γ′ microstructure becomes topologically inverted; connection of the γ′ rafts results in extensive transverse climb and an increase of the number of a?100? dislocation segments in the γ′ phase. 相似文献
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《Journal of Macromolecular Science: Physics》2013,52(4-6):777-785
The memory effect in PA11 films is studied in close relation with the crystalline structure. In polyamide 11, [(CH2)10–CO–NH] n , the polarity of the amide group induces hydrogen bonds between chains that are crucial to the crystalline structure and are responsible for the memory effect. During the forming from the melt, the polyamides are sheared, which leads to persistent chain alignments due to hydrogen bonds. In the present work, the crystalline structure of PA11 films has been studied by differential scanning calorimetry and wide angle x-ray scattering. The crystalline structure at room temperature depends on the cooling rate. A quench leads to the smectic δ′ structure, whereas a slow cooling favors the formation of the triclinic α phase in addition to the smectic δ′ phase. This study also shows the influence of an annealing in the melt on the crystalline structure. With increasing annealing time in the melt, the δ phase develops and the δ′ phase progressively vanishes. It seems necessary to maintain PA11 above the melting point for a long time to totally erase the structural evidence of the memory effect. 相似文献
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New phase formation at the La0.9Sr0.1MnO3/YSZ interface and its effects on the cathodic performances were studied at 900 °C in air. The resistance caused by the interfacial product layer kept increasing with time to reach up to 40% of the total resistance after 500 h. The interfacial product was identified as La2Zr2O7 by XRD measurement. The electrical conductivity of La2Zr2O7 (2.4 × 10−5 S cm−1 at 1000 °C), measured by AC impedance and current interruption methods, was 4 to 7 orders of magnitude smaller than those of La0.9Sr0.1MnO3 electrode or YSZ electrolyte. Either the electronic conductivity or the electrochemical O2 reduction activity of La2Zr2O7 was negligible. Combining these results, a conclusion was made that the cathodic degradation comes mainly from the growth of interfacial product layer and its contribution to the cell resistance increment is ohmic in nature. 相似文献
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Yoshinobu Nakamura Takuya Matsumoto Ken-ichi Miyazaki Masayo Noda Kazuki Takakura Ryota Tsutsumi 《Composite Interfaces》2017,24(8):761-778
The interfacial layer structure of a model incompatible polymer blend system was analyzed using 1H pulse nuclear magnetic resonance (pulse NMR) spectroscopy. Non-crosslinked and crosslinked poly(n-butyl methacrylate) particles with a mean size of ca. 0.9 μm were prepared by seeded emulsion polymerization, and the degree of crosslinking was varied. The particles were powdered using a freeze-dry method and dispersed in poly(vinyl chloride) by melt blending. Dynamic mechanical analysis indicated that the non-crosslinked particles were completely compatible. In contrast, mutual diffusion of the polymer chains in the crosslinked particles was restricted within the particle/matrix interfacial layer. As a result, an incompatible phase structure in which the crosslinked particles were dispersed in the continuous phase was formed. Pulse NMR analysis indicated that the interfacial layer thickness was in the range of 17–98 nm. The thickness decreased with an increase in the degree of crosslinking in the particles. The interfacial layer thickness in the particles was approximately 10 times larger than that for the incompatible polymer pair. Tensile test results indicated that the elongation at break was dependent on the thickness of the interfacial layer. The yield stress was developed for the particles with high hardness that was independent of the interfacial thickness. 相似文献
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U. Nowak J. Saalmüller W. Richter M. Heyen H. Janz 《Applied Physics A: Materials Science & Processing》1984,35(1):27-34
Infrared reflectivity measurements on vapour phase grownn-GaAs epitaxial layers (n=7×1016...5×1018 cm–3) deposited on semi-insulating GaAs:Cr substrates show interference structures whose strength cannot be explained by the interference pattern of a simple two layer system. Assuming a third very thin (0.4 m) interfacial layer it is possible to describe the experimental results. For Te doping the carrier concentration in the interfacial film is higher than in the volume of the epitaxial layer; it is lower for Sn doping. The results of this nondestructive optical method were confirmed by conductivity measurements while etching the sample. The origin of the interfacial layer is discussed in terms of non-steady state conditions at the beginning of the epitaxial growth. 相似文献
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本文考察了Fe-Fe50 wt.%Si扩散偶在1200℃ 无磁场以及稳恒磁场下扩散层生长规律. 利用真空浇注强制冷却技术制备Fe-Fe50 wt.%Si扩散偶, 将制备的扩散偶进行1200℃不同磁感应强度下的热处理. 对获得热处理后试样进行SEM与EDS线扫描分析, 结果表明, 无论无磁场还是稳恒磁场下Fe-Fe50 wt.%Si扩散偶均生成两个扩散层, 即FeSi相层和Fe-Si固溶体层, 并且发现0.8 T下的两个扩散层宽度均小于0 T磁场下试样. 按照抛物线规律, 计算了扩散偶中间扩散层的互扩散系数, 发现0.8 T磁场下FeSi相层和Fe-Si固溶体层的互扩散系数较无磁场下 分别降低了26.7%与34.1%. 通过对磁吉布斯自由能的计算, 发现0.8 T磁场对扩散激活能Q的影响不足以影响扩散过程. 但扩散过程中原子振动频率ν会受到磁场的影响, 进而影响扩散常数D0, 磁场对原子振动频率的影响可以用拉莫尔旋进理论进行解释.
关键词:
Fe-Fe50wt.%Si扩散偶
稳恒磁场
FeSi相
Fe-Si固溶体 相似文献
18.
在实际大气中,分子和粒子不仅遭受单次散射,还遭受多次散射。本文首先计算了多次散射在总散射量中的贡献。结果表明当光学厚度大于0.1时,多次散射在总散射量中的贡献将超过10%,因此必须考虑多次散射的作用。在多次散射辐射传输计算时,一般需把散射相函数展开为勒让德(Legendre)函数的多项式。有些介质如云或气溶胶粒子,散射相函数前向非常尖锐。展开的Legendre多项式需数百项甚至上千项才能收敛,而计算时间与展开项数的3次方成正比。本文介绍了在辐射传输计算时对尖锐相函数的δ-M和δ-fit处理方法,比较了两种方法的计算结果。当计算用的流数相同时,δ-fit方法的计算结果比δ-M方法的计算结果要精确得多;当计算结果精确度相同时,δ-fit方法的流数比δ-M方法的流数少得多,运算速度也快很多。δ-fit方法是目前处理散射相函数的理想方法,可以大大提高计算的精度以及缩减运算时间。 相似文献
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The structural evolution of misfit dislocation networks at γ/γ′ phase interfaces in Ni-based single crystal superalloys under tensile loading and temperatures is simulated by molecular dynamics. From the simulation, we find that, with increasing load or temperature, the patterns of dislocation networks on the (100), (110) and (111) phase interfaces change from regular to irregular or disappear. Under the same load and temperature, the dislocation networks of the different phase interfaces show different degrees and patterns of damage. The density and stability of the dislocation networks decrease with increasing temperature. When the interfacial dislocation networks become more regular, the γ/γ′ interfaces become more stable. The simulated results are supported by related experimental findings. Moreover, based on MD simulations, the averaged stress–strain responses for different phase interfaces under loading are presented. The results indicate that the combined influences of temperature and load play an important role for the structure evolution of misfit dislocation networks at γ/γ′ phase interfaces of Ni-based superalloys. 相似文献
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Mokarian-Tabari P Geoghegan M Howse JR Heriot SY Thompson RL Jones RA 《The European physical journal. E, Soft matter》2010,33(4):283-289
Thin films of polymer mixtures made by spin-coating can phase separate in two ways: by forming lateral domains, or by separating
into distinct layers. The latter situation (self-stratification or vertical phase separation) could be advantageous in a number
of practical applications, such as polymer optoelectronics. We demonstrate that, by controlling the evaporation rate during
the spin-coating process, we can obtain either self-stratification or lateral phase separation in the same system, and we
relate this to a previously hypothesised mechanism for phase separation during spin-coating in thin films, according to which
a transient wetting layer breaks up due to a Marangoni-type instability driven by a concentration gradient of solvent within
the drying film. Our results show that rapid evaporation leads to a laterally phase-separated structure, while reducing the
evaporation rate suppresses the interfacial instability and leads to a self-stratified final film. 相似文献