共查询到18条相似文献,搜索用时 187 毫秒
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本工作用示差热分析法,淬火样品X射线衍射法和Guinier-Lenn透射式高温单色聚焦粉末照相法研究了Fe-C-Sb合金中液态急冷获得的ε相的高温分解过程,实验结果指出,ε相在125℃开始分解,首先分解成ε-Fe2C,而后在450℃分解成α-Fe,并析出Sb和Fe3Sb2,还保留有ε-Fe2C;在550℃以后ε-Fe2C转变成Fe3C,并在770℃时发生Fe的α→γ转变,在800℃时主要组成相为:γFe,Sb,Fe3C(Fe3Sb分解);在冷却过程中750℃发生Fe的γ→α转变,冷至室温时的主要组成相是:αFe,Fe3C,Sb,Fe3Sb2。
关键词: 相似文献
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本工作用X射线粉末照相法研究了Fe-C-Sb合金中液态急冷获得的ε相在高压下的相变过程。实验结果表明,压力对ε相的稳定性及其相变过程都有显著影响。在4.7GPa压力下,ε相的稳定化温度提高到450℃左右,而后合金中开始出现在常压下未曾出现过的新的正交结构亚稳相。在上述压力下,当温度达到560℃时,该正交结构亚稳相开始转变成Fe3C;在800℃时,Fe3C分解成单质状态的石墨碳和γ-Fe,这时合金的相组成为:C,γ-Fe,Sb及另一未知相。
关键词: 相似文献
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实现了大体积Cu60Sn30Pb10偏晶合金的深过冷与快速凝固. 实验获得的最大过冷度为173 K(0.17TL). 凝固组织发生了明显的宏观偏析,XRD分析表明,试样上部是由固溶体(Sn),(Pb)相和金属间化合物ε(Cu3Sn)相组成的三相区,下部为富(Pb)相区. 在小过冷条件下,三相区中ε(Cu3Sn)相的凝固组织为粗大的枝晶,随着过冷度的增大,ε(Cu3Sn)相细化成层片状组织,且层片间距随过冷度的增大而减小,而(Sn),(Pb)两相始终以离异共晶的方式存在. 富(Pb)相区中分布有少量的ε(Cu3Sn)枝晶,枝晶长度随过冷度的增大而增大,且在大过冷条件下发生碎断. (Sn)相在ε(Cu3Sn)相表面形核、长大,其形态类似于包晶凝固组织.
关键词:
深过冷
快速凝固
偏晶合金
层片组织 相似文献
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通过在真空电弧熔炼炉内对合金铸锭进行反复熔炼处理,获得到了凝固组织不同的Zr65Al7.5Cu12.5Ni10Ag5合金铸锭.在相同的制备条件下,由凝固组织不同的合金铸锭通过吸铸法制备得到了薄片非晶合金.利用差示扫描量热法(DSC)对非晶合金的晶化动力学进行了分析.x射线衍射谱表明,在Zr65Al7.5Cu12.5Ni10Ag5非晶合金晶化过程中,二十面体准晶相(I相)作为初生相析出.Kissinger分析结果表明,合金铸锭的凝固组织细化,相对应的非晶合金发生晶化时,I相形成与分解的有效激活能都增大,说明非晶合金及析出的I相的热稳定性都提高.从结构的遗传性角度就合金铸锭凝固组织对相应非晶合金晶化过程中二十面体准晶相的形成动力学的影响进行了讨论.
关键词:
二十面体准晶相
晶化动力学
凝固组织 相似文献
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用分子动力学方法模拟了单晶铁(Fe)在一定初始温度下冲击相变(α相→ε相)的微观过程,结果显示温度会导致冲击相变压力阈值降低.基于此微观过程,对加卸载波系的传播规律进行了相应计算和分析,结果表明在卸载过程中逆相变波(ε相→α相)相对于波前以当地纵波声速传播,而相对波后以亚声速传播,这可由卸载压力-密度曲线给出相应解释;计算了不同初态的卸载压力-密度状态曲线,并给出了逆相变带的分布,其分布规律显示了卸载过程逆相变的滞后现象.
关键词:
分子动力学
多体势
冲击波
相变 相似文献
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利用定量相场模型, 以Mg-0.5 wt.%Al合金为例模拟了基面((0001)面)内镁基合金的等温自由枝晶生长过程. 通过研究该合金体系数值模拟的收敛性, 获得了最优化值耦合参数λ = 5.5及网格宽度Δx/W0 = 0.4, 并在该参数下系统研究了各向异性强度和过饱和度对枝晶尖端生长速度、尖端曲率半径、Péclet数及稳定性常数σ* 的影响. 结果表明, 由微观可解性理论得到的稳定性系数σ* 与ε6 拟合值σ*≅ ε6 1.81905, 更接近理想值σ * (ε6) ≅ε6 1.75. 此外, 当过饱和度Ω < 0.6时, 稳定性系数σ * 不随ε6 的变化而变化, 而当Ω > 0.6时, 稳定性系数σ * 随着ε6 的增加而减小. 这反映了枝晶的生长由扩散控制向动力学控制的转变. 随着过饱和度的增加, 枝晶形貌由雪花状枝晶向圆状枝晶转变. 相似文献
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A crystalline Sb–Cu alloy is investigated for use in Li-ion rechargeable batteries, and its structural, electrochemical and thermal properties are characterized. A pulse electrodeposition method is used to prepare Sb–Cu alloy film on Cu foil as a negative electrode. The structure of the alloy film electrode is characterized using XRD, FE-SEM and EDX. The electrochemical behavior of the Sb–Cu alloy film is investigated at the current rate of 0.1C to the cut-off potential range of 1.8 and 0.01 V vs. Li/Li+. Our experimental results demonstrate that the initial discharge capacity is 850 mAh g?1 and that the discharge capacity increases to 1034 mAh g?1 at the end of the 30th cycle with a stable cycle life. The Coulombic efficiency is approximately 83.5% with good cyclability. Moreover, the crystalline Sb–Cu alloy film has relatively low exothermic properties, and it may be an interesting candidate for use in the negative electrodes of Li-ion batteries. 相似文献
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C. O'Raifeartaigh A. Nylandsted Larsen F. Cristiano P. L. F. Hemment 《Applied Physics A: Materials Science & Processing》1995,61(6):579-585
Supersaturated solid solutions of substitutional, electrically active Sb have been obtained by ion implantation of relaxed epitaxial Si1?xGex alloy layers grown on compositionally graded buffers. Substitutional and nonsubstitutional Sb fractions in relaxed Si0.85Ge0.15, Si0.65Ge0.35 and Si0.50Ge0.50 alloy layers implanted to a dose of 5×1015 Sb cm?2 and annealed isothermally at temperatures ranging from 400 to 850°C have been studied by Rutherford backscattering/channeling, transmission electron microscopy and Hall-effect and sheet resistivity measurements. A supersaturated solution of Sb corresponding to a peak carrier concentration of 4×1020 cm?3 and an electrically active fraction of 40% of the implanted dose is observed by Hall measurements for the case of Si0.85Ge0.15 and Si0.65Ge0.35 alloys annealed at 550°C. 相似文献
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Graphene Nanosheets Suppress the Growth of Sb Nanoparticles in an Sb/C Nanocomposite to Achieve Fast Na Storage
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Hong‐Yan Lü Fang Wan Li‐Hua Jiang Guang Wang Xing‐Long Wu 《Particle & Particle Systems Characterization》2016,33(4):204-211
Presently, graphene incorporation is one of the most effective strategies to develop superior electrode materials for sodium‐ion batteries (SIBs). Herein, it is excitingly found that an incorporated graphene nanosheet in the preparation processes can not only completely protect all the Sb nanoparticles in an Sb/C composite from being inactivated, but also suppresses their growth to undesirable micrometer size. While there are still many exposed Sb particulates on the surface of pristine Sb/C microplates, the graphene‐incorporated Sb/C/G nanocomposite consists of uniform Sb nanoparticles of 20–50 nm, all of which have been protected by and wrapped in the mixed carbon network. When used as anode materials for SIBs, the Sb/C/G nanocomposite exhibits the best Na‐storage properties in terms of the highest reversible capacity (650 mA h g?1 at 0.025 A g?1), fastest Na‐storage ability (290 mA h g?1 at a high current density of 8 A g?1), and optimal cycling performance (no capacity decay after 200 cycles), in comparison to pristine Sb/C and pure Sb. It is further revealed that the much enhanced performance should originate from the improvement of Na‐storage kinetics and increase of electronic conductivity via comparing the electrochemical impedance spectra, and cyclic voltammetry profiles, as well as the polarization variation along with current densities. 相似文献
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用Co和Sb作为初始原料,通过机械合金化(mechanical alloying, MA)的方法合成了CoSb3,并系统研究了MA转速和MA时间对MA过程中固相反应的影响.XRD结果表明,相同MA转速下,CoSb3的量随MA时间的延长而增多,但是MA时间过长会导致大量CoSb2的生成,甚至诱发CoSb3分解为CoSb2和非晶态Sb.而提高MA转速,只能缩短固相反应的发生时间,而不会改变整个固相反应
关键词:
机械合金化
热电材料
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非平衡热力学 相似文献
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Hyun Woo Chung 《Applied Surface Science》2006,252(13):4545-4548
New ferroelectric Pb(Zr,Ti)O3-Pb(Mn,W,Sb,Nb)O3 (PZT-PMWSN) thin film has been deposited on a Pt/Ti/SiO2/Si substrate by pulsed laser deposition. Buffer layer was adopted between film and substrate to improve the ferroelectric properties of PZT-PMWSN films. Effect of a Pb(Zr0.52Ti0.48)O3 (PZT) and (Pb0.72La0.28)Ti0.93O3 (PLT) buffer layers on the stabilization of perovskite phase and the suppression of pyrochlore phase has been examined. Role of buffer layers was investigated depending on different types of buffer layer and thickness. The PZT-PMWSN thin films with buffer layer have higher remnant polarization and switching polarization values by suppressing pyrochlore phase formation. The remnant polarization, saturation polarization, coercive field and relative dielectric constant of 10-nm-thick PLT buffered PZT-PMWSN thin film with no pyrochlore phase were observed to be about 18.523 μC/cm2, 47.538 μC/cm2, 63.901 kV/cm and 854, respectively. 相似文献