时效温度对NiTiNb9合金相变温度及微观组织的影响

采用DSC、SEM等方法,研究了时效温度对马氏体相变及其逆相变温度、相变滞后、平均相变焓以及微观组织的影响.结果表明:在300～400℃,NiTiNb9合金存在一个敏感时效温度,在这个敏感温度区间处理,其相变温度会发生突变,而在这个敏感温度之前或之后的温度区间,NiTiNb9合金的相组成基本保持不变.微观组织分析表明,NiTiNb9合金在时效过程中析出的一些细小的β-Nb相颗粒,会形成应力场抑制马氏体的形核和长大,从而使得马氏体相变温度降低;与此同时,由于Nb元素的扩散,部分Nb将取代基体相中的Ni位置,引起基体中Ni/Ti原子比的微小变化,从而使马氏体相变温度发生变化.     

淬火温度对Co40.5Ni34Al25.5合金相变和磁性的影响

用金相显微分析、DSC和VSM方法研究了Co40.5Ni34Al25.5合金马氏体相变和Curie点随淬火温度的变化,通过三点弯曲试验研究其形状记忆效果.结果发现该合金马氏体相变温度和Curie点与淬火温度成正比关系.马氏体相变的4种温度,即Ms,Mf,As和Af基本平行变化,淬火温度每升高10℃,马氏体相变温度和Curie点升高8℃～9℃.β相中Al的含量随淬火温度升高而降低,因而使马氏体相变温度和Curie点升高.1320℃淬火的Co40.5Ni34Al25.5合金的弯曲强度约为450 MPa,弯曲试验表明Co40.5Ni34Al25.5合金有双向形状记忆特性.     

热处理工艺对Heusler型Ni2MnGa合金马氏体相变的影响

采用电弧熔炼法熔炼Ni48Mn31Ga21和Ni50Mn255Ga25两种合金,并对这两种合金进行了热处理,借助交流磁化率测定、金相显微镜观察、X射线衍射等手段研究了热处理工艺条件对非化学计量比的Ni48Mn31Ga21合金马氏体相变和结构有序度的影响.结果表明(1)Ni48Mn31Ga21合金相变特征温度为Ms=305K,Mf=297K,As=313K,Af=318K,居里温度Tc=366K;(2)与空冷态相比,淬火态的马氏体转变量降低,经过400℃退火后,随着保温时间t的延长,马氏体转变量上升,当t=50h时达到最大值;(3)Ni48Mn31Ga21合金经过900℃×4d+400℃×50h热处理后,有序度明显提高.     

氧含量对Ni47Ti44Nb9合金组织和相变行为的影响

研究了氧含量对Ni47Ti44Nb9合金显微组织和相变行为的影响.结果表明,当氧含量超过固溶度后,氧存在于(Ti,Nb)4Ni2O氧化物中.随着氧含量的增加相变温度降低,应力诱发马氏体相变的临界应力提高,相变热滞变宽.氧含量(质量分数)在0.04%-0.07%范围内,Ni47Ti44Nb9合金具有最大的形状记忆应变和延伸率.     

热处理对TiNi形状记忆合金回复稳定性能的影响

研究了热处理对TiNi合金回复稳定性能的影响。结果表明,马氏体相变温度Msσ和Mfσ随热机械循环次数增加而上升,而马氏体逆相变温度Asσ和Afσ随热机械循环次数的增加而下降。随着热机械循环次数的增加,相变温度逐步稳定。退火温度小于500℃,热机械循环下TiNi合金的回复性能稳定,退火温度达550℃时,TiNi合金组织长大,应力诱发马氏体变形时容易发生滑移,回复应变随热机械循环次数增加而下降,回复稳定性能变差。     

Ni47Ti44Nb9形状记忆合金时效处理及机理

采用真空感应法制备高铌含量Ni47Ti44Nb9形状记忆合金,结合电阻法测量和差示扫描量热法,探索了不同热处理制度对马氏体相变温度的影响,结果表明,炉冷的时效冷却方式能明显降低其马氏体相变开始温度Ms,且随着时效温度的增加,Ms逐渐降低.进一步采用第一原理计算方法,通过计算NiTi(Nb)的形成热、结合能以及电子结构,表征和评判了Nb在NiTi基体相中的固溶方式,结果显示Nb元素优先置换Ti位,这种置换方式一方面增强了Nb-Ti和Ni-Ti之间的键合强度,提高了NiTi基体的稳定性,另一方面也增加了Ni/Ti原子比.     

Co40Ni33.5Al26.5合金马氏体相变、磁性与淬火温度的关系

Co-Ni-Al合金不仅可以作为铁磁性形状记忆合金,也是传统和高温形状记忆合金的候选材料,本文通过金相显微分析,DSC和VSM方法,研究了Co40Ni33.5Al26.5合金马氏体相变和Curie点随淬火温度变化的情况,结果发现该合金马氏体相变温度和Curie点与淬火温度成正比关系.马氏体相变的4种温度,即Ms、Mf、As和At基本平行变化,淬火温度每升高10℃,马氏体相变温度升高8～9℃,而Curie点升高6～7℃.其马氏体相变温度和Curie点随淬火温度的变化与基体相β的成分变化有关,β相中Al的含量随淬火温度升高而降低,因而马氏体相变温度和Curie点升高.并且发现随着淬火温度升高,Co40Ni33.5Al26.5合金马氏体相的磁晶各向异性有减弱的倾向.     

定向凝固Ni_(47)Mn_(32)Ga_(21)多晶合金的结构、相变及磁特性

采用定向凝固方法制备了Ni47Mn32Ga21多晶合金,通过XRD谱和金相照片研究合金的结构,通过对合金磁化强度与温度关系、电阻与温度关系、磁化曲线和磁感生应变曲线的测量分析,研究了合金的相变、磁化特性及磁感生应变特性。结果表明:Ni47Mn32Ga21合金在室温(298K)时为四方结构马氏体相,晶格参数a=b=0.593 8 nm,c=0.553 1 nm。合金的马氏体相变起始温度Ms和终止温度Mf分别为309 K和295 K,逆马氏体相变起始温度As与终止温度Af分别为306 K和319 K,居里温度TC为365 K。室温无压力下,Ni47Mn32Ga21合金有较好的双向可恢复磁感生应变,其饱和磁感生应变值达到-700×10-6。     

高温环境下Ni47Ti44Nb9形状记忆合金拉伸行为研究

在25～450℃内,沿轧向及横向研究了Ni47Ti44Nb9形状记忆合金的高温拉伸力学性能.结果表明:在室温下,沿轧向拉伸时出现了明显的应力平台,而沿横向拉伸则无此现象,这是由于不同的解孪晶机制造成的.当温度升高至100、300℃时,屈服强度增加,而断裂时的最大应变减小,在此温度下Ni47Ti44Nb9合金变得更加硬而脆.随温度进一步升高到450℃,Ni47Ti44Nb9合金的抗拉强度迅速减小,断裂时的最大应变再次增加,这表明此时合金变软,粘性增强.     

Ti-Ni-Nb宽滞后形状记忆合金的应力诱发马氏体相变行为

用在（Ms＋30℃）温度下的拉伸实验和差示扫描量热仪（DSC）较系统地研究了Ti44Ni47Nb9宽滞后形状记忆合金应力诱发马氏体的相变行为。研究结果表明：当形变量达到14％左右时，应力诱发马氏体相变过程基本完成。应力诱发马氏体的逆相变温度间隔要比热诱发马氏体约小一个数量级。形变对该合金应力诱发马氏体的逆转变开始温度、逆转变温度间隔以及相变潜热均有明显影响，随着拉伸变形量的增加而增加。而在随后的冷却循环中，相变潜热和马氏体相变开始温度均随着形变的增加缓慢降低。     

X-ray diffraction study of Ba0.985Na0.015Ti0.985Nb0.015O3, Ba0.6Na0.4Ti0.6Nb0.4O3 and Ba0.3Na0.7Ti0.3Nb0.7O3 compositions

The Ba_0.985Na_0.015Ti_0.985Nb_0.015O₃, Ba_0.6Na_0.4Ti_0.6Nb_0.4O₃ and Ba_0.3Na_0.7Ti_0.3Nb_0.7O₃ compositions of the (1 − x) BaTiO₃–xNaNbO₃ (BTNNx) system have been studied by X-ray diffraction and by measurements of dielectric properties. The specimens with composition BTNN (x = 0.015, 0.40 and 0.70) have been refined by the JANA program from X-ray powder diffraction data. Ceramic samples with composition (1 − x) BaTiO₃ + xNaNbO₃ (where x = 0.015, 0.40 and 0.70) were prepared by calcinations from appropriate mixture of BaCO₃, TiO₂, Na₂CO₃ and Nb₂O₅. The calcined powder was sintered at temperature range 1200–1400 °C. As the composition x increased from 0.015 (and 0.70), the ferroelectric ceramics (x = 0.015, FE) with tetragonal phase changed to the ferroelectric relaxors (RFE, x = 0.40). RFE ceramics showed a peculiar diffuse phase transition and dielectric relaxation at the low temperature (down to 180 K) due to a frustration between RFE and FE state. These ceramics present the classical ferroelectric character when 0 ≤ x < 0.075 and 0.55 < x ≤ 1 and relaxor character when 0.075 ≤ x ≤ 0.55.     

Magnetic, electrical and plastic properties of Fe76Nb2Si13B9, Fe75Ag1Nb2Si13B9 and Fe75Cu1Nb2Si13B9 amorphous alloys

Influence of 1 h annealing in vacuum on magnetic, electrical and plastic properties of Fe₇₆Nb₂Si₁₃B₉, Fe₇₅Ag₁Nb₂Si₁₃B₉ and Fe₇₅Cu₁Nb₂Si₁₃B₉ melt spun ribbons were carefully investigated. It was shown that in all cases soft magnetic properties can be significantly enhanced by applying 1-h annealing at characteristic temperatures T_op. This optimization annealing causes that permeability increases more than 15-times and magnetic losses (tangent of loss angle) achieves a minimum in relation to the as quenched state. Using structural examinations (X-ray and HRTEM) it was shown that for the Fe₇₅Cu₁Nb₂Si₁₃B₉ alloy the optimized microstructure corresponds to a nanocrystalline αFe(Si) phase whereas in other alloys to a relaxed amorphous phase free of iron nanograins. As a consequence of this fact the Fe₇₆Nb₂Si₁₃B₉ and Fe₇₅Ag₁Nb₂Si₁₃B₉ alloys show higher plasticity in comparison to the nanocrystalline Fe₇₅Cu₁Nb₂Si₁₃B₉ alloy. Temperatures of the first stage of crystallization, and related diffusion parameters were determined using measurements of resistivity versus temperature with different heating rates.     

Fe2+-Ni2+-NH3-NH4+-C2O42-H2O体系的沉淀配合平衡热力学

针对草酸盐配位共沉淀热分解还原法制备超细铁镍合金粉过程中Fe2+-Ni2+-NH3-NH4+-C2O42--H2O体系的溶液平衡建立热力学分析模型,并根据模型进行相关计算,揭示反应体系中各物质随pH值、氨及草酸浓度的变化关系。结果表明:溶液中的Fe主要以[Fe(C2O4)n]2 2n络合物形式存在,而铁氨络合物含量很低。当氨含量较低时,溶液中的Ni主要以[Ni(C2O4)n]2 2n存在;氨含量较高时,在酸性条件下,溶液中的Ni主要以[Ni(C2O4)n]2 2n存在,在碱性条件下,则主要以[Ni(NH3)n]2+存在。低pH值下,Ni的沉淀率较Fe的高,而高pH值下,Ni的沉淀率则较Fe的低。     

Thermodynamics and phase diagrams in the binary systems Na2O-SiO2, Na2O-GeO2, Na2O-B2O3, Li2O-B2O3, CaO-B2O3, SrO-B2O3, and BaO-B2O3

We applied our model to the enthalpy of mixing data of the binary systems Na₂O-SiO₂, Na₂O-GeO₂, Na₂O-B₂O₃, Li₂O-B₂O₃, CaO-B₂O₃, SrO-B₂O₃, and BaO-B₂O₃. The most stable composition in the liquid, that is where the enthalpy of mixing is most negative, is with a metal-oxygen ratio of 4 to 3, for monovalent metals (Na and Li) and 3 to 4 for divalent metals (Ba and Ca) in liquid silicates or borates. The same applies to the CaO-SiO₂, CaO-Al₂O₃, PbO-B₂O₃, PbO-SiO₂, ZnO-B₂O₃, and ZnO-SiO₂ systems. The oxygen to metal ratio, its constant value in various types of systems, reflects and describes the structure of the liquid. Using the analyzed enthalpies of mixing data and the available phase diagrams, we calculated the enthalpies of formation of the various binary compounds. The results are in excellent agreement with data in the literature that were obtained from direct solid-solid calorimetry.     

New Zr6CoAs2-type compounds: Y6CoBi2, Ho6CoBi2 and Tm6CoBi2

Results of a powder X-ray diffraction investigation of new ternary compounds are reported. The compounds Y₆CoBi₂ [a=0.8312(1) nm, c=0.4144(1) nm], Ho₆CoBi₂ [a=0.8246(2) nm, c=0.4095(1) nm], and Tm₆CoBi₂ [a=0.8155(2) nm, c=0.4066(1) nm] crystallize in the hexagonal Zr₆CoAs₂-type structure (space group P6b2m No. 189). The Zr₆CoAs₂-type structure is a superstructure of the Fe₂P-type structure.     

Zur Kenntnis von RbBa3Ca4Cu3V7O28

Single crystals of RbBa₃Ca₄Cu₃V₇O₂₈ were prepared above the melting point of the reaction mixture. It crystallizes with hexagonal symmetry, space group C_6V⁴-P6₃mc, a 11.1751, c 12.434 Å, Z = 2. RbBa₃Ca₄Cu₃V₇O₂₈ is the second member of a new structure type of the copper-oxovanadates. Ba²⁺ shows an unusual 12-fold coordination. The two calcium positions are coordinated by trigonal prisms and octahedra respectively. The copper coordination is characterized by a stretched square pyramid. The Cu²⁺ ions are outside the centre nearly in plane of the pyramids.

Zusammenfassung

Einkristalle von RbBa₃Ca₄Cu₃V₇O₂₈ wurden oberhalb des Schmelzpunktes der Reaktionsmischung erhalten. Die Verbindung kristallisiert hexagonal, Raumgruppe C_6V⁴-P6₃mc, a 11.1751, c 12.434 Å, Z = 2. RbBa₃Ca₄Cu₃V₇O₂₈ ist das zweite Beispiel für einen neuen Strukturtyp der Kupfer-Oxovanadate, mit 12-fach koordinierten Ba²⁺ -Ionen. Die zwei Calciumpositionen sind trigonal prismatisch bzw. oktaedrisch koordiniert. Die Koordination der Cu²⁺-Ionen ist durch eine gestreckte Pyramide charakterisiert. Cu²⁺ ist auβerhalb des Polyederzentrums nahezu in der quadratischen Fläche der Pyramide angeordnet.     

Al2O3-Sm2O3-CeO2电解质的性能（英文）

采用溶胶-凝胶法和低温燃烧技术制备Ce1-xSmxO2（x=0,0.1,0.2,0.3）和掺杂Sm和（2%-8%）Al2O3的二氧化铈;研究其合成、结构、致密化、导电性和热膨胀等性能,并利用XRD研究其结构和相组成。结果表明,于1300°C烧结球团,获得致密的陶瓷,于1250°C在Ce0.8Sm0.2O0.2中加入2%和4%的Al2O3以促进烧结。利用扫描电子显微镜观察烧结后球团的表面形貌,使用双探针交流阻抗谱研究总离子电导率。     

电弧喷涂制备Fe65Cr20Mo7B3.5SiMn1.5W3涂层

在Q235低碳钢板上利用电弧喷涂工艺进行喷涂,以制得Fe65Cr20Mo7B3.5SiMn1.5W3涂层。喷涂材料为自行配制的丝材,按照35%的填充率将配好的粉填充到U型不锈钢外皮中,经过多道拉拔、挤压工艺制成Φ2mm的粉芯丝材。采用X射线衍射仪、扫描电镜、能谱分析仪、透射电镜对涂层的物相和组织形貌及成分进行了表征;采用差示扫描量热仪、显微硬度仪等设备对涂层的热稳定性及显微硬度进行了检测和分析。试验结果表明:涂层组织形貌呈典型的层状组织结构,由变形良好的带状粒子相互搭接堆积而成。涂层含有50.63%的非晶相,同时含有纳米级的晶相。涂层组织均匀、结构致密、孔隙率低,并且涂层硬度高达1040.5HV0.3,属硬质涂层,具有良好的热稳定性。     

Synthesis and electrochemical properties of LiNi0.4Mn1.5Cr0.1O4 and Li4Ti5O12

Spinel compound LiNi_0.4Mn_1.5Cr_0.1O₄ (LNMCO) and Li₄Ti₅O₁₂ (LTO) were synthesized by the sol-gel method and the solid-state method, respectively. The particle sizes of the products LiNi_0.4Mn_1.5Cr_0.1O₄ and Li₄Ti₅O₁₂ were 0.5 to 2 um and 0.5 to 0.8 um, respectively. All samples exhibited excellent electrochemical properties. A LiNi_0.4Mn_1.5Cr_0.1O₄/Li₄Ti₅O₁₂ (LNMCO/LTO) cell was fabricated and was demonstrated to exhibit good electrochemical properties at the high current rate of 1 C. When the specific capacity was determined based on the mass of the LNMCO cathode, the LNMCO/LTO cell delivered 125 mAh g⁻¹ at 1 C and 77 mAh g⁻¹ at 5 C. The capacity retentions after 30 cycles were 94.4 % and 83.1 %, respectively.