Y对Fe50- x Mo14Cr15C15B6Y x非晶合金 非晶形成能力及耐腐蚀性能的影响

采用单辊法制备Fe50-xMo14Cr15C15B6Yx(x=0,2)非晶合金条带,利用X射线衍射、差热分析、透射电镜和电化学极化曲线方法对非晶合金的结构、非晶形成能力(GFA)、热稳定性、晶化过程及腐蚀行为等进行了研究和表征.结果表明:Fe50-xMo14Cr15C15B6Yx合金能够形成非晶合金,随着Y元素的添加,其非晶相含量、非晶形成能力及热稳定性显著提高.晶化处理后,析出的主要晶体相为α-Fe,Fe23B6,Cr23C6和Fe3Mo3C等.Fe50-xMo14Cr15C15B6Yx非晶合金在质量分数为3.5%NaCl水溶液中呈现出极强的耐腐蚀能力,远优于常用耐蚀不锈钢Cr18Ni9Ti,并且随着Y元素的加入,非晶合金的耐腐蚀能力进一步提高,具有更宽的钝化区间及更低的腐蚀电流密度.     

Centimeter-scale-diameter Co-based bulk metallic glasses with fracture strength exceeding 5000 MPa

Co48-xFexCr15Mo14C15B6Er2 (x = 2.5 and 5) bulk metallic glasses (BMGs) with critical size (dc) up to 15 mm in diameter were synthesized by copper mold casting. Co43Fe5Cr15Mo14C15B6Er2 BMG has a wide supercooled liquid region (84 K) and ultrahigh fracture strength exceeding 5000 MPa,which is the highest value for reported metallic glasses with dc exceeding 1 cm. Furthermore,the Poisson ratio,Young modulus,shear modulus and bulk modulus of this alloy were evaluated to be 0.31,217 GPa,82 GPa and 214 GPa,respectively. The ideal configurational entropy of Co48-xFexCr15Mo14C15B6Er2 (x = 0 and 5) has been calculated. The introduction of the similar element Fe in the Fe-free Co-Cr-Mo-C-B-Er alloy will be beneficial to increasing the ideal config-urational entropy and depressing the critical cooling rate to achieve greater glass-forming ability. The combination of superior glass-forming ability and ultrahigh fracture strength makes the present Co48-xFexCr15Mo14C15B6Er2 (x = 2.5 and 5) BMGs promising candidates as advanced structural materials.     

稀土元素R对储氢合金(LaRMg)(NiCoAlZn)_(3.5)相结构和电化学性能的影响

以(LaRMg)(NiCoAlZn)3.5(R=La、Ce、Pr、Nd、Gd、Y和Sc)合金为研究对象,研究稀土元素R部分替代La后对合金相结构和相组成及电化学性能的影响.XRD和EPMA方法分析结果表明,合金(LaRMg)(NiCoAlZn)3.5退火组织主要由Ce2Ni7型相(或Gd2Co7型)、PuNi3型相和CaCu5型相组成;Ce、Pr和Nd元素的替代对合金相组成没有明显影响,而Gd元素替代使合金中CaCu5型相明显减少,Ce2Ni7型(或Gd2Co7型)相显著增加,其相丰度达到79.03%;Y和Sc元素替代时合金中Gd2Co7型相基本消失.电化学测试和分析表明, 稀土元素R替代La后对合金电极活化性能影响不大,其中Nd、Gd、Y和Sc部分替代La在一定程度上提高合金的最大放电容量,而Gd元素替代时合金电极容量最高达到343.1 mAh/g;Gd和Nd元素部分替代La使合金电极的循环稳定性得到明显提高,S100分别达到95.3%和93.0%.此外,Sc部分替代La能有效改善合金电极的高倍率放电性能.     

镁基大块非晶玻璃转变的动力学性质

用真空吹铸法制备了直径2 mm的Mg65Cu25Y6Gd4与Mg65Cu25Gd10块体非晶合金棒,采用X射线衍射分析(XRD)、差热分析(DTA)分别对非晶合金的结构和形成能力进行了研究.以Mg65Cu25Y6Gd4与Mg65Cu25Gd10大块非晶合金DTA实验为基础,利用Kissinger方程对其玻璃转变的动力学性质从不同方面进行了研究.分析结果表明:玻璃转变表观激活能与频率因子v0越小,玻璃转变处Lasocka关系的B值越大,则对于同一合金系表现出玻璃形成能力(GFA)越强,这一现象是由于大块非晶合金独特的结构特点所引起的.     

La3-xYxMgNi14(x=0～2)贮氢合金的相结构与电化学性能研究

系统研究了La3-xYxMgNi14(x=0,1.0,1.5,2.0)贮氢合金的相结构和电化学性能.结构分析表明,合金均由Gd2Co7和Ce2Ni7型结构相组成.随Y含量值x的增加,Gd2Co7型相的丰度增加,Ce2Ni7型相的丰度减少.合金各相的晶胞参数(a,c)和晶胞体积(V)均随x的增加而线性减小.电化学研究表明,随着Y含量的增加,合金电极最大放电容量减小,活化性能显著降低.合金随x的增加,HRD值减小与合金电极电催化活性及氢在合金相中的扩散速率的减小有关.     

Y_(41)Sc_(15)Al_(24)Co_(20)大块非晶合金的制备及其晶化动力学行为

利用铜模吸铸法制备直径为5 mm的Y41Sc15Al24Co20大块非晶合金,采用连续加热和等温加热方法对其晶化动力学行为进行研究.利用Kissinger方程得出该合金的晶化激活能为3.02 eV.用Johnson-Mehl-Avrami (JMA)方程描述合金的等温晶化过程,在不同等温温度下计算得出Avrami指数大于3.0,合金的主要晶化过程为三维形核长大过程.在Arrhenius方程的基础上,得到合金的区域Avrami指数和阶段晶化激活能随晶化体积分数变化的关系曲线.     

热处理对Fe_(40)Co_(40)Zr_7V_2B_9Ta_2合金微观结构及磁性能的影响

采用单辊快淬法制备Fe40Co40Zr7V2B9Ta2非晶合金薄带,并对该合金在不同温度下进行热处理.利用差热分析(DTA)、X射线衍射(XRD)、扫描电镜(SEM)和振动样品磁强计(VSM)测量合金的热性能、微观结构及磁性能.结果表明:Fe40Co40Zr7V2B9Ta2合金的初始晶化产物为α-FeCo相,高温时析出ZrCo3B2,Co23Zr6和ZrB2相;薄带横断面的形貌在快淬态和300℃退火后,合金的自由面呈网状结构,贴辊面呈枝状结构;高于550℃退火,横断面呈颗粒状;550℃退火后合金的矫顽力(Hc)最小,高于550℃退火,Hc随退火温度的升高而增大.     

Cr、V元素替代Nb元素对Fe40Co40Zr8Nb2B10非晶合金热性能及结构的影响

采用单辊快淬法制备Fe40Co40Zr8Nb2B10、Fe40Co40Zr8Cr2B10和Fe40Co40Zr8V2B10非晶合金薄带,并对三种合金在不同温度下进行热处理.利用X射线衍射仪(XRD)和差热分析仪(DTA)等测试手段对样品的结构及热性能进行研究.结果表明,Fe40Co40Zr8Nb2B10、Fe40Co40Zr8Cr2B10和Fe40Co40Zr8V2B10合金的晶化激活能分别为302.6、306.6和299.3 kJ/mol,Cr元素和V元素替代Nb元素对合金的热稳定性影响不大,但扩大了合金的晶化温区.三种合金晶化过程相似:非晶→非晶+α-FeCo→α-FeCo+ZrCo3B2+Fe(Co)3Zr.     

YPO_4∶Re(Re=Eu,Gd)荧光粉的合成及荧光性质研究（英文）

采用化学共沉淀法在不同温度下制备了YPO_4∶Re(Re=Eu,Gd)荧光粉;通过X射线粉末衍射分析显示合成的荧光粉为四方磷钇矿结构;通过扫描电子显微镜(SEM)观察了荧光粉的形貌,晶粒大小在0.2~0.4um之间,XRPD和SEM结果表明,YPO_4∶Re(Re=Eu,Gd)的最佳烧结温度为1000℃;荧光光谱测试显示样品有3个主要发射峰,最强峰出现在595nm处。     

Formation of Fe56Mn5Cr7Mo12Er2C12B6 amorphous steel

The Fe48Cr15Mo14Er2C15B6 amorphous steel can hardly be used as an engineering material because of its extreme brittleness and very low iron content. By changing the composition of the nonmagnetic amorphous steel, and using the relation between the reduced glass transition temperature Trg and the glass forming ability, a new amorphous Fe56Mn5Cr7Mo12Er2C12B6 alloy with good glass forming ability and high iron content was obtained. The diameter of the as-cast sample rod reached 8 mm. This new amorphous steel has lower manufacturing cost due to its high iron content,and thus it can have wider applications.     

Ni2+对NixZn1-xFe2O4铁氧体磁性能的影响

文章采用粉末冶金烧结法制备了不同Ni2+摩尔分数的Ni-Zn铁氧体粉料,并采用XRD、SEM、VSM对粉体进行表征,采用MATS-2000型磁性材料自动测量仪对环形磁芯进行测量.研究结果表明:样品的比饱和磁化强度随x的增大先增大后减小,在x=0.6达到最大值43.82 A· m/kg;环形磁芯的剩磁随x的增大先增大后减...     

Ti_(62)Zr_(17)Cu_6Ni_(15)合金晶化实验分析

对Ti6 2 Zr1 7Cu6 Ni1 5非晶合金原始样品进行了退火晶化处理和激波晶化处理 ,对样品作了XRD分析并重点对样品进行了差示扫描量热分析 (DSC)以及动力学分析 .看到了许多有趣的现象并得到了一些有价值的动力学参数     

(+)-4-(2-甲基丁基)-4′-氰基联苯的合成

以(+)-对甲苯磺酸-2-甲基丁酯与联苯基溴化镁反应,在催化剂作用下实现手性戊基与联苯偶联,再经碘化和氰化,合成了(+)-4-(2-甲基丁基)-4′-氰基联苯(CB-15)。总收率为15%(以左旋戊醇计算)。同时,就手性戊基与联笨偶联的机理等问题作了讨论。     

Nd4.5-xTbxFe75.5B20(x=0;1)纳米晶的磁性

利用熔体快淬和晶化热处理法制备了成分为N d4.5-xT bxF e75.5B20(x=0;1)的纳米晶复合永磁合金,采用x射线衍射及V SM分析研究了材料的显微结构与磁性.结果显示,退火工艺对两种合金磁性能的影响显著,且原子分数为1%的稀土元素T b掺杂明显提高了材料的磁性.     

封闭性硼烷B15H15^2—（D3h）的结构及稳定性的从头算分析

利用量子化学从头算方法在ＨＦ／６－３１Ｇ水平上，优化计算了带两个负电荷的封闭型硼烷Ｂ１５Ｈ２－１５（Ｄ３ｈ）的结构，能量和正则振动频率。结果表明，它是ＨＦ／６－３１Ｇ势能超曲面上的真实稳定点。理论预测，它在化学上和动力学上都是稳定的。     

(Z)-15-二十四碳烯酸的选择性合成

从易得原料芥酸(2)出发,通过酯化、还原、溴代反应得到溴代二十二碳烯(5),将5分别通过与乙酰乙酸乙酯和与丙二酸二乙酯反应生成中间体6和7,二者经成酸水解后脱羧均得到了具有药物活性的目标化合物(Z)-15-二十四碳烯酸,产物经甲酯化后通过GC-MS检测,其顺式结构比例大于90%.其结构经NMR,IR和MS表征.     

CeO2掺杂(Bi0.5Na0.5)0.94Ba0.06TiO3压电陶瓷的电子性能与微观结构

采用传统陶瓷工艺制备了CeO2掺杂(Bi0.5Na0.5)0.94Ba0.06TiO3(缩写为 BNBT6)无铅压电陶瓷.研究了CeO2掺杂量(0～1.0wt%)对BNBT6陶瓷的密度、相结构、微观结构及介电与压电性能的影响.XRD表明,CeO2掺杂量在0～1.0%wt之间变化,没有改变BNBT6陶瓷纯的钙钛矿结构.SEM表明,少量的CeO2掺杂,改变了陶瓷的微观结构.介电温谱表明,随着CeO2掺杂量的增加,铁电相向反铁电相转变温度(Td)降低. 室温下,CeO2掺杂量为0.4wt%时,BNBT6陶瓷样品有很好的性能:密度为5.836g/cm3,压电常数为136pC/N,平面机电藕合系数为30.3%, 相对介电常数为891, 介电损耗为0.0185.     

Thermoelectric properties of phase separated Ti substituted Zr_(0.75)Hf_(0.25)NiSn_(0.985)Sb_(0.015) half-Heuslers

Sb is a very effective dopant for ZrNiSn based half-Heusler alloys.The effect of Ti substitution on Zr_(0.75)Hf_(0.25)NiSn_(0.985)Sb_(0.015) half-Heusler(HH) semiconductor alloys has been investigated to explore the structural modifications and composition variation.TixHf_(0.25) Zr_(0.75-x)NiSn_(0.985)Sb_(0.015)(x=0,0.15,0.30,0.45) alloys were synthesized by induction melting.A set of samples was also annealed for comparative studies.The samples were then sintered using plasma activated sintering(PAS) technique.XRD results confirmed the existence of ZrNiSn type HH compounds.Backscattered electron(BSE) images showed phase separations in the samples.Ti substitution improved the carrier concentration and electrical conductivity of the alloys.Moreover,thermal conductivity was also significantly reduced due to the enhanced phonon scattering.Consequently,a ZT value of 1.11 at 873 K was obtained for 30% Ti substituted(annealed) sample.     

La_2O_3掺杂对BaBi_4Ti_4O_(15)陶瓷压电性能的影响

采用传统固相烧结工艺制备了La掺杂量分别为0,0.1,0.25,0.5 mol的BaBi4Ti4O15 (BBT) 压电陶瓷.通过SEM和XRD分析了BBT陶瓷的表面形貌和物相结构;用介电常数测试仪(LCR)和准静态d33测试仪分别测量了陶瓷的介电常数,介电损耗和压电常数.结果表明:A位La掺杂并未改变BBT陶瓷的晶体结构; 虽然随着La掺杂量的增加(从0～0.5 mol),陶瓷的烧结温度有所提高(从1120℃提高到1150℃),然而它拓宽了BBT陶瓷的烧结温区(从20℃提高到50℃),并细化了陶瓷晶粒; La掺杂量为0.1时,BBLT陶瓷的压电常数比未掺杂的陶瓷增大了将近一倍(13pC/N),同时,与其它掺杂量的BBLT陶瓷相比,该掺杂量的BBLT陶瓷具有同频率下最大的介电常数及最小的介电损耗.     

Preparation and catalytic performance of Fe-SBA-15 and FeO x /SBA-15 for toluene combustion

High-surface-area and well-ordered mesopor- ous Fe-incorporated SBA-15 （xFe-SBA-15） and SBA-15- supported FeOx （yFeOx/SBA-15） with the Fe surface den- sity between 0.09 to 1.11 Fe-atom/nm2 have been prepared using the one-step synthesis and incipient wetness impregnation methods, respectively. Physicochemical properties of these materials were characterized by means of numerous techniques, and their catalytic activities for the combustion of toluene were evaluated. It is found that the xFe-SBA-15 and yFeOx/SBA-15 samples possessed rod- or chain-like morphologies. The Fe species were of high dispersion when the Fe surface density was lower than 0.76 Fe-atom/nm2 in xFe-SBA-15 and 0.64 Fe-atom/nm2 in yFeOx/SBA-15. At a similar Fe surface density and space velocity, the xFe-SBA-15 catalysts showed better activity than the yFeOJSBA-15 catalysts, in which the xFe-SBA- 15 catalyst with Fe surface density 0.59 Fe-atom/nm2 performed the best. It is concluded that the good perfor- mance of the xFe-SBA-15 sample with Fe surface density 0.59 Fe-atom/nm2 was associated with its large surface area, high Fe species dispersion, and good low-temperature reducibility.