FULL-ELECTRON CALCULATION OF α-LaNi5H0.5 and β-LaNi5H3

在全电子水平上,基于广义梯度近似密度泛函和全势线性缀加平面波方法,计算出了LaNi5储氢合金固溶相α-LaNi5H0.5与中间相β-LaNi5H3的晶体结构、态密度和电荷密度等特征.在α相区域中,通过对5种不同间隙位置的能量计算得到12n位最稳定;点阵常数a随着H原子增多而增大,而c基本为一常数.在α→β相区域中,a值随着H原子的增多进一步增大,而c值增大相对较小.计算值与实验结果一致.     

铝合金化对LaNi5-xAlx电子结构的影响

在全电子水平上,基于广义梯度近似密度泛函和全势能线性缀加平面波方法,计算了不同Al含量LaNi5-xAlx(x＝0,0.5,1.0)的晶体结构、能带结构、状态密度等特征.对LaNi5的计算表明:GGA Perdew96的计算结果可信,自旋极化对优化结构和能量的影响不明显;对LaNi4Al的研究表明Al原子最可能取代3g位的Ni原子;对LaNi4 5Al0.5的优化结构与实验结果一致.随着Al含量的升高,晶胞能量、费米面能量升高,如从LaNi5,LaN45Al05到LaNi4Al,费米面能量从-10.591、-10.134 eV升高到-9.441 eV,而Ef上的态密度和材料对应的低温比热容则急剧下降,态密度从11.81、8.86急剧降低到1.61 eV/f.u..并计算给出了LaNi4.5Al0.5的能带结构、状态密度图.     

NiCrAlFe精密电阻合金中的L12有序结构研究

有序结构的形成是决定NiCrAlFe精密电阻合金电学性能的关键因素。本文利用第一性原理赝势平面波方法,计算了合金处于无序固溶体结构和形成L12型有序结构时的结合能、态密度、晶格常数等参数,并利用高分辨透射电子显微镜（HRTEM）对合金进行了结构表征,还测试了固溶态和时效态的电阻率。从结合能来看,该合金形成L12有序结构时比无序固溶体更加稳定;态密度以及部分态密度计算结果则表明,在L12有序结构中,Ni、Cr、Al、Fe会强烈成键而使得整个合金体系变得稳定;HRTEM分析结果证明固溶态合金经过和时效处理后出现了L12有序结构,而且该有序结构的晶格常数与计算值基本一致。对比无序固溶体与L12型有序结构费米能级处的态密度值发现,当形成L12有序结构时合金的导电能力较无序固溶体下降,电阻率升高,与实际测试结果吻合。     

Ni_(74.6)Al_xMo_(25.4-x)合金早期沉淀过程的微观相场模拟

采用三元微观相场动力学模型研究Ni74.6AlxMo25.4-x合金早期沉淀过程,对合金的微观组织演化图像、平均序参数和原子占位概率进行了分析。结果表明:合金首先析出L10和L12相,析出的L10相原位转变为L12相。随着Al浓度的增加,原子聚簇和有序化的进程加快。Ni原子倾向于占据αⅠ位和αⅡ位,Al原子和Mo原子倾向于占据β位。随着Al原子浓度的增加,Ni原子和Al原子在αⅠ和αⅡ位的占位概率增加,Mo原子在αⅠ和αⅡ位的占位概率降低,Al原子在β位占位概率增加,Ni原子和Mo原子在β位的占位概率降低。     

微观相场模拟Ni64Al21V15合金中L12、DO22相形成的原子迁移

利用微观相场动力学模型研究Ni64Al21V15合金1150K下的L12相、DO22相转变的过程,详细分析合金元素在两相中不同原子面和各个格点上的占位几率及其演化过程,探讨原子迁移机制。研究发现Ni64Al21V15合金沉淀过程L12相向DO22相结构转变存在两种晶体学位向关系类型:(001)L12→(001)DO22和(001)L12→(100)DO22。Al、V和Ni原子首先在原子面间跃迁,由均匀、无序的状态分别向各原子面富集,同时发生有序化反应。Al和V原子优先占据β和β1位(以Al原子为主),Ni原子优先占据α1和β2位。随后Al、V和Ni原子在面内迁移,Al原子占据β1和α1位,V原子占据β和β2位,Ni原子主要占据α1位,从而实现L12相转变成DO22相。     

快速凝固Al—Fe—V—Si合金微结构Mossbauer谱研究

用Mossbauer谱研究了快速凝固Al－Fe－V－Si合金的微结构，结果表明，合金中Fe原子存在α－Al（Fe），α－Al（Fe－Fe）替代固溶体及α－Al13（Fe，V）3Si金属间化合物三种组态，高温热曝露状态除4.3％Fe合金（原子分数）α－Al（Fe－Fe）组态消失外，其它合金组态类型不变，但含量发生相对变化，急冷态和退火态α-Al晶格常数随合金中Fe含量增加呈现不同程度的下降趋势，归因于两种状态组分原子Fe，V和Si含量的变化。     

Sb、Bi合金化提高Mg-Al系合金抗蠕变性能的机理

采用基于密度泛函理论的Dmol 4.1程序,从合金形成热、结合能、热力学性能和态密度等方面,研究Sb、Bi合金化提高Mg-Al系合金抗蠕变性能的影响机理。结果表明：Sb、Bi分别置换Mg-Al系合金Mg17Al12相中Mg（Ⅰ）,Mg（Ⅱ）,Mg（Ⅲ）和Al原子时,仅Sb置换Mg17Al12相中Mg（Ⅰ）,Mg（Ⅱ）原子,Bi置换Mg17Al12相中Mg（Ⅰ）原子能形成稳定的Mg17Al12固溶体结构,这表明Sb、Bi在Mg17Al12中固溶量有限。进一步比较合金化形成稳定的固溶体结构,发现Sb、Bi合金化后,固溶体结构的稳定性比未合金化时增强,其中,Sb置换Mg17Al12相中Mg（Ⅱ）原子时,其结构稳定性最高,其次Sb置换Mg17Al12相中Mg（Ⅰ）原子,再次Bi置换Mg17Al12相中Mg（Ⅰ）原子;而析出金属间化合物Mg3Bi2和Mg3Sb2,比相应合金化Mg17Al12固溶体的结构更稳定。不同温度下热力学性能的计算发现,合金体系中形成了结构稳定性高的Sb、Bi合金化Mg17Al12固溶体以及金属间化合物Mg3Sb2和Mg3Bi2,这些相高的结构稳定性并不因温度的升高而消失,其结构稳定性仍比Mg17Al12相高,因此Sb、Bi合金化提高了Mg-Al系合金的抗蠕变性能。电子态密度的分析结果进一步表明,Mg-Al系合金中相结构稳定性提高的主要原因在于：Sb、Bi合金化后,体系费米能级以下低能级区成键电子数的增多,其来源主要是Mg（s）、Mg（p）、Al（p）、Bi（d）和Sb（d）的价电子。     

Sb、Y、Nd元素对Mg-6%Al合金显微组织的影响

本文主要研究了Sb、Y和Nd元素复合添加时对Mg-6%Al合金铸态组织的影响.研究结果表明,Sb、Y和Nd元素对Mg-6%Al合金组织均有细化作用,当元素复合添加0.5%Y 1.0%Nd时,晶粒平均直径由102.04μm细化至57.47 μm,细化效果最为显著.经测试分析,Sb、Y、Nd与合金中镁铝元素形成热稳定性较高的金属间化合物Mg3Sb2、Al2Y和Al2Nd,各相在α-Mg晶粒内和晶界均有分布,在凝固期间,首先析出并成为α-Mg的异质核心,细化了合金的铸态组织.     

LaNi4.75Al0.25储氢材料的密度泛函理论研究

在全电子水平上，基于广义梯度近似（GGA）密度泛函和全势能线性缀加平面波方法（FLAPW），研究了LaNi4.75Al0.25的晶体结构。采用GGA Perdew96交换相关泛函，计算给出了LaNi4.75Al0.25的晶胞参数为a=b=0．5033nm、c=0．4018nm、a／c=1．252，Al原子最可能占据的3g格位的等效位置（0．75，0，0．5），计算还给出了合金的能带结构、态密度（DOS）和电荷密度图，计算结果与实验值符合得相当好。     

一水硬铝石(α-AlOOH)及其(010)表面的密度泛函研究

采用基于密度泛函-赝势的量子化学方法研究了一水硬铝石(α-AlOOH)晶体及其(010)表面的原子和电子结构.研究表明: GGA-PBE几何优化得到的晶体结构参数与实验测定数据相符; 通过体相原子间重叠布局分析确定了α-AlOOH(010)表面最容易解理的位置; 通过一系列测试计算选择原子层数为4, 真空层厚度为7.5的slab模型模拟α-AlOOH(010)表面, 结果表明表面原子发生弛豫, 且驰豫表面的表面能为0.491J/m2; 根据表面态密度分析、表面原子排布情况和前线轨道理论推测, 阴离子捕收剂很难与一水硬铝石(010)的表面Al原子间发生化学作用, 却容易与水硬铝石(010)的表面H原子相互作用.     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

新型的治疗阿尔茨海默氏症药物(1-二甲基磷酰基-2,2,2-三氯)-乙基-1-醇烟酸醋对体外神经细胞的作用

目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基^-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L^-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L^-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L^-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

The Mirror with Patterns of Auspicious Animals and Grapes——Exquisite cast mirror and the technology of surface tin-enrichment by rubbing-in and infiltration of tin-rich powder

<正>Bronze mirrors were used by the Chinese people before the introduction of the glass mirror.Only after it was replaced by the glass mirror did the bronze mirror gradually retreat from people's lives.Different styles of bronze mirrors were made in different historical periods,particularly in the Warring States Period,the Han and Tang Dynasties,which were the three peaks of the development of bronze mirror arts in ancient China.The casting techniques were exquisite.The surface of the bronze mirror was smooth and bright enough to reflect one's image,and there were scarcely any casting defects on the mirror surface.On the back of the bronze mirror,there were rich depictions of Arts and Humanities,and the ornamentations were also     

The 9th China International Diecasting Congress & Exhibition

The 9th China International Diecasting Congress ＆ Exhibition was held on July 22-24, 2014 at Shanghai New International Expc Centre. This exhibition was the most successful over the years, with over 6890 visitors and 155 exhibitors, and the exhibition area increased by 30% from 9,500 square meters in 2012 to 12340 square meters. Die casting enterprises from a total of 24 countries and regions, including China mainland, Chinese Taiwan and Hong Kong, South Korea, Japan, Germany, India, Thailand, Malaysia, the United States, Russia, Australia, Iran, Ukraine, Brazil, Colombia, Singapore, Austria, Canada, Croatia, France, Turkey, United Kingdom, Vietnam, attended the congress and exhibition.     

Introduction of the Fluid Control Engineering Institute of Kunming University of Science and Technology

正The Fluid Control Engineering Institute of Kunming University of Science and Technology was set up in 1996.The researches of institute concentrate on electro-hydraulic(pneumatic)servo/proportional control and hydromechatronics.The Institute is committed to research and development of electro-hydraulic control of high-end technical equipment in ferrous metallurgy refining produc-     

RARE METALS Volume Contents

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