Structure modification of rapidly solidified Al-11 wt% Si alloy by the addition of 2 wt% Fe

An investigation of the structure formation of as-cast Al-11 wt% Si (AlSi11) and Al-11 wt% Si-2 wt% Fe (AlSi11Fe2) rapidly solidified (RS) ribbons is performed. Ribbon samples are examined in detail using Auger electron spectroscopy (AES) and transmission electron microscopy (TEM). A nanoscale thickness layer of Si-precipitations, at both Al-grains boundary and oxide/Al-matrix interface, is found to be characteristic for “pure” AlSi11 ribbons. For Fe-doped ribbons, this layer comprises Fe-containing phase also, which appears to possess amorphous nature and is situated between the Si-grains and Al-matrix. A possible mechanism of altering the thermally activated volume diffusion of elements, due to the effect of Fe on the structure modification, is speculated based on the obtained results.     

快速凝固Mg94.6Zn4.8Y0.6镁合金薄带的组织与性能

采用单辊快速凝固技术制备了Mg94.6Zn4.8Y0.6合金薄带,研究了薄带的组织及性能特征。结果表明:Mg94.6Zn4.8Y0.6镁合金快速凝固薄带组织由过饱和的单相-αMg固溶体组成,沿厚度方向分为两个晶区:近辊面粗大等轴晶区和自由面细小等轴晶区。Mg94.6Zn4.8Y0.6合金快速凝固薄带的显微硬度为85.95HV,在250℃左右保温2 h的显微硬度最高,超过该温度(250~300℃)显微硬度显著下降。     

熔体快淬La1-xNdxFe11．5Si1．5（x=0，0．3，0.5）化合物磁性能和磁熵变

利用熔体快淬法制备了La1-xNdxFe11．5Si1．5（x=0，0．3，0.5）快淬带。通过X射线衍射和振动样品磁强计测试了回火态（1000℃，5h）La1-xNdxFe11．5Si1．5）快淬带的相组成和磁性能。结果表明：不同成分快淬带回火后均可得到稳定的NaZnl，型化合物。和常规的熔炼法相比，用熔体快淬法通过短时间的回火（1000℃，5h）可以制成具有大磁熵变的NaZn13型的化合物。用Nd替代部分的La后，居里温度略有提高，同时保持有大的磁熵变｜△S｜；并且随着Nd含量的增加，有效制冷温区有变宽的趋势。     

铜磷非晶箔带钎料的制备及性能研究

利用液态单辊急冷法和传统铸造技术分别制备出成分相同的Cu68.5Ni15.7P6.5Sn9.3非晶箔带钎料和普通钎料,制得的非晶铜磷钎料箔带成型性良好,对折180°不断.将两种钎料在四种钎焊温度(660、670、680和690℃)和三种保温时间(5、10和15 min)下与紫铜进行真空钎焊,借助DTA、XRD进行分析.结果表明,制备的非晶箔带钎料与相同成分的普通钎料相比,前者熔点低于后者;在同一钎焊条件下,前者润湿性优于后者.     

基于铁基非晶薄带巨磁阻抗效应的位移传感器

利用铁基非晶薄带的特性研制了一种新型的非接触位移传感器.介绍了铁基非晶薄带的磁敏特性、处理方法及位移传感器电路的设计,并对传感器的特性进行了测试.结果显示:所设计的位移传感器重复性好,最大偏差为0.2973％、迟滞小,最大为0.6526％.     

Investigation on transverse defect and cavitation depth in ferrous pipe using melt spun FeSiB ribbon as magnetostrictive sensing element

The investigation addresses the scope of rapidly quenched Fe₈₀Si₈B₁₂ ribbons as magnetostrictive sensor (MsS) material to generate guided waves in galvanised iron pipe and evaluation of defects with different geometries and dimensions. Enhancement in the effective defect size (EDS) of transverse and pit type defects increased the MsS signal. However, the backwall echo showed opposing trend (transverse: reduced and pit: increased) with increase in dimensions of these defects. Such behaviour of backwall intensities has been correlated to different type of guided wave strain field distributions around these defects and reflection coefficients.     

处理电流密度对钴基非晶薄带巨磁阻抗效应的影响

本文研究了焦耳处理工艺的处理电流密度对Co68.15Fe4.35Si12.5B15和Co71．8Fe4．9Nb0.8Si7．5B15非晶薄带巨磁阻抗效应的影响。样品在不同电流密度下进行了处理。实验结果表明：焦耳处理存在最佳电流密度,对Co68.15Fe4.35Si12.5B15窄带来说,最佳处理电流密度为30A／mm^2,处理后样品的阻抗变化率峰值和灵敏度分别为119％和73％／Oe;对Co71．8Fe4．9Nb0.8Si7．5B15窄带来说,最佳处理电流密度为35A／mm^2,处理后的阻抗变化率峰值为232％,灵敏度在30A／mm^2时达到42％／Oe。处理后样品的内应力得到有效释放,软磁性能提高,使薄带的巨磁阻抗效应较淬态时有了明显提高。处理电流密度是焦耳处理方法中影响钴基非晶薄带巨磁阻抗效应的一个重要参数。     

Magnetic properties of melt-spun ribbons(Sm_(1-x)Zr_x)(Fe_(0.92)Ti_(0.08))_(10) with ThMn_(12) structure and their hydrides

The structure and magnetic hysteresis properties of the cast Sm_(1-x)Zr_x(Fe_(0.92)Ti_(0.08))_(10)(x = 0-0.3)alloys and melt-spun ribbons prepared from them were studied.In the cast alloy with x0.2, a considerable amount of the eutectic phase is found in the SEM micrographs.Analysis of the temperature dependences of the magnetic susceptibility and XRD patterns allows amorphous state in the as-spun ribbons with x0.2 to be determined.The specific magnetization measured in a field of 17 kOe and remanence decrease with increasing annealing temperature from 800 to 900 ℃ and weakly depend on Zr concentration.The maximal value of coercivity Hc = 4.7 kOe is obtained on the ribbons with x = 0.2 after annealing at 850℃ for 10 min.After additional hydrogenation of the ribbons,both the coercivity and remanence increase by 54% and 7%,respectively.     

Nitrogen‐Doped Graphene Ribbon Assembled Core–Sheath MnO@Graphene Scrolls as Hierarchically Ordered 3D Porous Electrodes for Fast and Durable Lithium Storage

Graphene scroll is an emerging 1D tubular form of graphitic carbon that has potential applications in electrochemical energy storage. However, it still remains a challenge to composite graphene scrolls with other nanomaterials for building advanced electrode configuration with fast and durable lithium storage properties. Here, a transition‐metal‐oxide‐based hierarchically ordered 3D porous electrode is designed based on assembling 1D core–sheath MnO@N‐doped graphene scrolls with 2D N‐doped graphene ribbons. In the resulting architecture, porous MnO nanowires confined in tubular graphene scrolls are mechanically isolated but electronically well‐connected, while the interwoven graphene ribbons offer continuous conductive paths for electron transfer in all directions. Moreover, the elastic graphene scrolls together with enough internal voids are able to accommodate the volume expansion of the enclosed MnO. Because of these merits, the as‐built electrode manifests ultrahigh rate capability (349 mAh g^?1 at 8.0 A g^?1; 205 mAh g^?1 at 15.0 A g^?1) and robust cycling stability (812 mAh g^?1 remaining after 1000 cycles at 2.0 A g^?1) and is the most efficient MnO‐based anode ever reported for lithium‐ion batteries. This unique multidimensional and hierarchically ordered structure design is believed to hold great potential in generalizable synthesis of graphene scrolls composited with oxide nanowires for mutifuctional energy storage.     

合金元素对(NdPr)_6Fe_(79)B_(15)非晶厚带的晶化行为及磁性能影响

利用熔体快淬法制备了(Nd Pr)6Fe79B15和(Nd Pr,Dy)6Fe74.5Co3Cu0.5Zr1B15非晶带。通过X射线衍射(XRD)和差热分析(DSC),并借助Kempen模型和Kissinger方程,研究了合金的非晶晶化过程及非等温晶化动力学。结果表明,与(Nd Pr)6Fe79B15合金相比,(Nd Pr,Dy)6Fe74.5Co3Cu0.5Zr1B15合金的非晶形成能力明显提高,在9 m/s的辊速下获得了厚度为100μm以上的非晶厚带。2种合金的非晶厚带具有不同的晶化过程及晶化动力学机制。(Nd Pr)6Fe79B15合金的晶化分4步完成:非晶相(A)→Nd2Fe23B3+A’→α-Fe+Fe3B+Nd2Fe23B3’→α-Fe+Fe3B+Nd2Fe14B→α-Fe+Fe3B+Nd2Fe14B+Nd1Fe4B4;而(Nd Pr,Dy)6Fe74.5Co3-Cu0.5Zr1B15合金的晶化分两步完成:非晶相(A)→Fe3B+A’→α-Fe+Fe3B+Nd2Fe14B。与(Nd Pr)6Fe79B15合金由界面控制的多晶型晶化不同,(Nd Pr,Dy)6Fe74.5Co3Cu0.5Zr1B15合金第1步为界面控制的多晶型晶化,第2步则以扩散控制的共晶型晶化为主。由于退火后组织结构的细化和改善,(Nd Pr,Dy)6Fe74.5Co3Cu0.5Zr1B15合金带的磁性能明显优于(Nd Pr)6Fe79B15合金带。