双相纳米晶合金的晶化体积分析

通过计算机模拟双相纳米晶合金(Fe0.5Co0.5)73.5Nb2V1Si13.5B9Cu1的X射线衍射峰,得出了合金经不同温度纳米晶化后的晶化体积,在520℃退火后合金晶化已基本完成,晶化体积达85%以上。对于(Fe0.5Co0.5)73.5Nb2V1Si13.5B9Cu1合金经不同温度退火后生成的纳米晶合金及其他合金退火后生成的纳米晶合金其晶化体积将会随退火温度的增加而增加,从而使其在高温下的软磁性能越趋于稳定。利用该方法得出的结果对纳米晶合金的这一特性解释得很好。这对研究双相纳米晶软磁合金的性能和结构特别是高温纳米晶的高温性能具有一定的意义。     

脉冲磁场处理非晶合金产生的纳米晶化相的磁伸性质

低频脉冲磁场处理工艺,使非晶薄带Fe78Si9B13产生纳米晶化,析出α-Fe(Si)纳米相,形成α-Fe(Si)纳米晶与剩余非晶的双相纳米合金。穆斯堡尔谱分析,随着脉冲磁场的强度提高,双相纳米晶合金的晶化相体积分数增加。纳米晶化相α-Fe(Si)的磁致伸缩系数λcs为-1.287×10-4～-1.345×10-4。控制晶化相体积分数,可以使双相纳米晶合金的有效磁致伸缩系数λes最小,有利于提高双相纳米晶合金的软磁性能。     

低频脉冲磁场处理Co_(68.15)Fe_(4.35)Si_(12.5)B_(15)的穆斯堡尔谱研究

用低频脉冲磁场处理非晶合金Co68.15Fe4.35Si12.5B15,用穆斯堡尔谱结合透射电镜对处理前后的试样进行了微结构分析。结果表明,在低频脉冲磁场处理下,非晶合金Co68.15Fe4.35Si12.5B15发生了纳米晶化,晶化析出相为体心立方α-Fe(Si),析出量为2.743%~23.960%,晶粒尺寸约2~10 nm,且晶化量与磁场强度和脉冲频率均有关系。     

利用直流高压电场使非晶态合金纳米化的研究

利用直流高压电场处理非晶态合金使之纳米化的研究。非晶态合金Fe73.5Cu1Nb3Si13.5B9在低于初始晶化温度140℃以下，由于高压电场的作用发生晶化，析出大小为2－10nm的α-Fe(Si)晶粒，延长处理时间，晶化效果好，晶粒数明显增多。     

固相法制备Ca_2La_8Si_6O_(26):Eu红色荧光粉

采用高温固相法制备新型Ca2La8Si6O26:Eu红色荧光粉,通过使用X射线衍射、相对亮度仪以及荧光光谱仪对制备的样品进行测试。结果表明:合成的荧光粉主晶相为Ca2La8Si6O26,并且可被394nm的近紫外光和464nm的蓝光有效激发,产生红光发射,主发射峰位置位于614nm(5 D0→7F2)。通过合成制度的研究,确定Ca2(La0.7Eu0.3)8Si6O26红色发光粉的最佳煅烧合成温度为1 400℃,Ca2(La1-xEux)8Si6O26中Eu3+的最佳制备浓度x=0.3。采用4.5%(摩尔分数)Li2CO3作为助熔剂,或添加0.05的Bi 3+离子作为敏化剂,可有效提高1 400℃煅烧的Ca2La8Si6O26:Eu的发光性能。并且还通过改变基质阳离子进行改性,发现阳离子为Ca2+时,发光性能最好。     

表面机械研磨/异步轧制无取向硅钢薄带的渗硅行为

对w（Si）=3%无取向硅钢进行表面机械研磨处理（SMAT）和异步轧制（CSR）,获得表面纳米结构,再进行550～650℃、4 h固体粉末渗硅处理,用透射电镜（TEM）、扫描电镜（SEM）和X射线衍射仪（XRD）研究表层组织演变。结果表明：经过SMAT后,w（Si）=3%无取向硅钢表面形成了等轴状、取向呈随机分布的、晶粒尺寸为10 nm的纳米晶组织;异步轧制后,表面纳米晶组织保持不变;550～650℃、4 h渗硅处理后,SMAT＋CSR样品表面形成化合物层,其厚度随着温度的升高由17μm增加到52μm;化合物层由Fe3Si和FeSi相组成.     

高强度Ti-Ni-Nb合金的制备与压缩性能

采用铜模铸造法制备了直径为2 mm的三元Ti90-xNixNb10(x=30,33,36)系列合金.利用X射线衍射(XRD)、扫描电镜(SEM)及压缩试验等方法研究了合金的相结构、显微组织和力学性能.结果表明:Ti-Ni-Nb系合金由Ti2Ni块体相和NbNi3枝晶相组成.随着合金元素Ni的增加,NbNi3枝晶相逐渐增多,Ti2Ni相逐渐减少.力学性能表明,随着Ni含量的增加,其合金断裂强度不断增加,当Ni含量为36 at.%时,合金Ti54Ni36Nb10的断裂强度达到了1950 MPa,且其塑性变形量约为1.5%.     

Si3N4/TiC纳米复合陶瓷材料显微结构

利用日立H-800透射电境、日立S-570型扫描电境及RAX-10A型X射线衍射仪对Si3N4/TiC纳米复合陶瓷材料的微观组织、结构和成分进行了研究.结果表明,TiC纳米颗粒弥散分布在基体β-Si3N4晶内和晶界,所制备的材料为晶内/晶间混合型纳米复合陶瓷.通过对Si3N4/TiC纳米复合陶瓷材料断裂方式的观察表明,材料断裂为沿晶断裂和穿晶断裂复合型,纳米粒子对裂纹扩展起到偏转和钉扎作用.纳米Si3N4颗粒的加入促进了基体长柱状β-Si3N4晶粒多峰分布的形成,类晶须晶粒在裂纹扩展过程中产生桥接和拔出.     

Al-Cu-Fe-Ce准晶中间合金的显微组织及热膨胀系数研究

针对准晶材料的脆性问题,通过常规铸造法制备了四元(Al_(63)Cu_(25)Fe_(12))_(100-x)Ce_x(原子数分数x=2,3,5,7)准晶中间合金,采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)以及透射电子显微镜(TEM)等,分析了铈含量对合金组织及热膨胀系数的影响。结果表明:随着铈含量的增加,合金中的二十面体准晶Ⅰ相的含量逐渐降低,含铈相发生一定程度的富集和粗化,当铈含量增加至7%时,合金中细小分布的不规则块状Al_(13)Ce_2Cu_(13)相明显减少,出现了团絮状的Al_8CeCu_4相;且随着铈含量的增加,合金的热膨胀系数先降低后又升高,含铈量为5%时,合金的热膨胀系数达到最小值。     

水热法制备低热导率 PbS 热电材料

通过纳米结构或声子工程降低热导率是改善PbS热电材料性能的重要途径。利用水热法制备Pb_(1-x)Bi_xS纳米热电材料,并对其热导率进行测试。结果表明,制备的纳米PbS的热导率比文献中PbS的热导率低10%左右。随着掺入Bi元素的增加,增加了晶体内部缺陷, Pb_(0.9)Bi_(0.1)S样品的热导率比PbS单体的热导率降低了33%。     

Melt-spun Al_(70-X)Si_(30)Mn_X (X=0,3,5,7,10) anode in lithium-ion batteries

Al70-XSi30MnX (X=0, 3, 5, 7, 10, mol%) ribbons were prepared by melt spinning. A supersaturated solid solution of Si and Mn in fcc Al and some microstructures consisting of nano grains were obtained. Some alloys with nano-sized grains exhibited high discharge capacities and favorable cycle properties. The capacity of more than 400 mAh/g could be obtained in melt-spun Al67Si30Mn3 alloy after 20 cycles and more than 300 mAh/g after 40 cycles. Li/Si and Li/Al compounds in the anodes of pure Al and pure Si were...     

Structure and photoluminescence of mullite-Ge nanocomposite

Al12Si3.75Ge0.25O26 ceramic powder was prepared by sol-gel method using Al（NO3）3,Si（OC2H5）4 and Cl3GeCH2-CH2COOH as precursors.The structural formation of Al12Si3.75Ge0.25O26 ceramic powder was analyzed by XRD.After reduction by flowing H2/Ar mixture gas,strong room temperature photoluminescence （PL） can be observed at 565 nm,613 nm,682 nm,731 nm and 777 nm,respectively.The PL intensity scarcely depends on the reduction temperature and duration,while the sample reduced at 500 ℃ for A^3 hours has the highest PL intensity.Before and after reduction at 500 ℃,the volume of unit cell of mullite solid solution decreases to 0.4699 3.Based on the analysis of XPS and Raman spectra,it can be approved that the PL phenomenon at room temperature is caused by the embedded Ge nanoparticles with the average size of about 1.95 nm.     

Formation and corrosion properties of Fe-based bulk metallic glasses

Bulk metallic glass (BMG) formation was explored in the Fe-B-Si-Nb alloy system though combined use of the atomic cluster line approach and the minor alloying strategy. The basic ternary compositions in the Fe-B-Si system were determined by the intersection points of two cluster lines, namely, Fe-B cluster to Si and Fe-Si cluster to B. 3at%-4at% Nb was added to the quaternary Fe-B-Si-Nb alloy. The casting experiments revealed that good glass-forming ability (GFA) occurred at the (Fe73.4Si8.2B18.4)96Nb4 composition, and 3-mm diameter BMG samples were made. The glass transition temperature (Tg), crystallization temperature (Tx, and supercooled liquid region (△Tx=Tx-Tg) of this BMG were measured to be 866, 889, and 23 K, respectively. The BMG shows a high Vickers hardness of about Hv 1164, a Young's modulus of 180 GPa, and a good corrosion resistance in the solutions of 1 mol/L HCl and 3 wt% NaCl.     

Melt-spun Al<Subscript>70−<Emphasis Type="Italic">X</Emphasis></Subscript>Si<Subscript>30</Subscript>Mn<Subscript><Emphasis Type="Italic">X</Emphasis></Subscript> (<Emphasis Type="Italic">X</Emphasis>=0, 3, 5, 7, 10) anode in lithium-ion batteries

Al_70−X Si₃₀Mn _X (X=0, 3, 5, 7, 10, mol%) ribbons were prepared by melt spinning. A supersaturated solid solution of Si and Mn in fcc Al and some microstructures consisting of nano grains were obtained. Some alloys with nano-sized grains exhibited high discharge capacities and favorable cycle properties. The capacity of more than 400 mAh/g could be obtained in melt-spun Al₆₇Si₃₀Mn₃ alloy after 20 cycles and more than 300 mAh/g after 40 cycles. Li/Si and Li/Al compounds in the anodes of pure Al and pure Si were not detected in Al-Si-Mn alloys inserted by Li. It is considered that the formation of the supersaturated solid solution and refinement of microstructures have prevented the alloys from the forming the compounds with superfluous Li. As a result, the electrochemical properties have been improved. Supported by the National Natural Science Foundation of China (Grant No. 50371066)     

一个新的环型三核铜配合物的晶体结构研究

用2-羟基-1,3-丙二胺（L）与高氯酸铜反应得到了一个三核铜金属杂环配合物[Cu3（L^-）3]（ClO4^-）3,用X-射线晶体结构分析方法表征了其结构．该晶体属三斜晶系,P-1空间群,晶胞参数a=1．0491（2）nm,b=1．0808（2）nm,c=1．2467（2）nm,a=74．451（3）°,β=70．635（3）°,γ=63．661（3）°,V=1．1829（3）nm^3,Z=4,R=0．0587,wR=0．1363．在配合物的阳离子中,三个铜离子均与相邻配体上的两个氮原子和两个桥联氧原子配位形成四配位平面四方形构型,且通过与三个配体2-羟基-1,3-丙二胺上的桥联氧原子连接形成一个由Cu^2＋和氧原子交错联接的六元杂环结构．     

Synthesis and Dielectric Properties of New Niobate Ba_5BiTi_3Nb_7O_(30)

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Sn-Ag-Cu-Sb无铅焊料物理性能

为了获得不同性能的电子封装焊料,制备了掺杂Sb(锑)的Sn-3.35Ag-0.7Cu无铅焊料合金,并对其密度、杨氏模量、硬度等重要物理性能进行了测定.测得该无铅焊料的密度为7.2106g/cm3,杨氏模量为43 GPa,硬度为96.7 N/mm2.实验结果表明,同未掺杂Sn-3.35Ag-0.7Cu焊料合金相比,硬度略...     

Effects of yttrium on the formation and magnetic properties of bulk metallic glassy （Fe, Co）-B-Si-Nb alloys

The bulk metallic glassy (BMG) rods of [(Fe0.5Co0.5)0.72B0.192Si0.048Nb0.04]100-xYx (x=0-6) and [(FexCo1-x)0.72B0.192Si0.04]Nb0.04]96Y4 (x=0.5-0.8) were prepared by copper mold casting. The structure, thermal stability,and magnetic properties of the samples were studied by X-ray diffraction (XRD), differential scanning calorimetry (DSC), and vibrating sample magnetometer (VSM). Adding lat% to 6at% of yt-trium, the bulk glassy alloy rods of [(Fe0.5Co0.5)0.72B0.192Si0.048Nb0.04]100-xYx (x=0-6) with the diameter of 3 mm were not formed, and the sample with 4at% of yttrium showed less crystalline phase than others. When the Fe/Co atomic ratio was between 5:5 and 7:3, the bulk glassy alloy rods of [(Fe1-xCox)B0.192Si0.048Nb0.04]96Y4 (x=0.5-0.8) with the diameter of 2 mm were fabricated. In the (Fe, Co)-B-Si-Nb-Y BMGs, when the Fe content increased, the thermal stability, the supercooled liquid region, and the glass-forming ability (GFA) decreased, but the saturation magnetization (Ms) increased.     

微波散射MCM-41介孔分子筛担载醋酸镧的制备及表征

水热法合成了纯硅MCM-41介孔分子筛,通过微波散射制备了系列不同硅镧摩尔比的LaAc／MCM-41（LaAcM）介孔分子筛。通过XRD、IR、N2吸附脱附等方法对分子筛的晶体结构和表面物性进行了表征。结果表明,当担载量n（Si）：,2（La）=30：1．0时,LaAcM Hammett碱量最大,为0．20mmol／g,／40介于＋6．8与＋4．6之间,比表面积为1287m^2／g,孔容0．8273cm^3／g,孔径2．571nm。样品具有典型的六方介孔结构特征。