Effect of Y<Subscript>2</Subscript>O<Subscript>3</Subscript> particles on microstructure formation and shear properties of Sn-58Bi solder

In the present study, varying weight percentages of Y₂O₃ particles (3–5 μm) from 0 to 3% were incorporated into eutectic Sn-Bi solder matrix to form composite solders. It is found that the reinforcement particles were well dispersed in the solder matrix. They depressed the growth of intermetallic compound (IMC) layers and reduced the size of IMC grains. Since the Y₂O₃ particles serve as additional nucleation sites for the formation of primary Bi-rich phase, the size of both Bi-rich phase and the IMCs were decreased gradually with the Y₂O₃ content increasing. Shear tests were also conducted on as—soldered joints. The growth of solid-state intermetallic compounds layer was examined by thermal aging of the solder/Cu couple for a temperature range from 60 to 120°C and time periods from 50 to 500 h. Compared with Sn-58Bi solder, finer eutectic microstructures were obtained with Y₂O₃ addition after long time aging. The apparent activation energies calculated for the growth of the intermetallic compound layers were 72 ± 5 kJ/mol of Sn-58Bi, 74 ± 4 kJ/mol of Sn-58Bi-0.5wt%Y₂O₃, 81 ± 5 kJ/mol of Sn-58Bi-1wt% Y₂O₃ and 81 ± 7 kJ/mol of Sn-58Bi-3wt.% Y₂O₃, respectively.     

Composition design and mechanical properties of ternary Cu–Zr–Ti bulk metallic glasses

The new compositions of ternary Cu–Zr–Ti bulk metallic glasses are predicted by integrating calculation of vacancy formation energy, mixing enthalpy and configuration entropy of the alloys based on thermodynamics of glass formers. The monolithic amorphous rods of 3 mm diameter have been successfully fabricated, and characterized by X-ray diffractometry, differential scanning calorimetry, scanning electronic microscopy, transmission electronic microscopy and compression tests. The results show that the designed alloys possess good glass forming ability and excellent mechanical properties. The mechanical properties of the samples can be effectively improved by regulating their composition. The monolithic amorphous rod of Cu₅₀Zr₄₄Ti₆ exhibits a high fracture strength of 1855 MPa and excellent plastic deformation up to ∼7.4%. The formation and propagation of shear bands in samples are also investigated. The enhancement of plastic deformation is mainly contributed to multiplication and intersection of shear bands.     

方管内表面等离子体离子注入动力学GPU-PIC仿真

内表面改性近年日益受到人们重视。本文采用基于Graphic Processing Unit(GPU)的Particle-in-cell(PIC)模型对方形管内表面的离子注入动力学过程进行数值仿真研究。结果表明在注入过程中,辅助地电极周围形成离子空穴,随时间延长,离子空穴发生交联并不断扩展,直至所有离子注入到方管内壁。离子空穴的形成和扩展使得在管内部形成离子密度波,密度波的传播速度随时间增加。由于等离子体鞘层的不均匀重叠使得管内的初始鞘层厚度分布不均,其中位于拐角附近的鞘层较厚,从而又导致了方管内壁周向上的注入剂量和能量分布存在不均匀性,内壁平面附近位置的注入剂量和注入能量均相对较大,而拐角附近的离子注入剂量和能量最小。本文采用GPU加速PIC的算法取得了高达90的加速比,极大缩短了等离子体粒子模拟的计算时间。     

3种不同导电纤维的大应变传感特性的比较研究

针对不同基体纤维,即PA6、Lycra和XLA,研究了3种具有PPy(聚吡咯)涂层的柔性导电纤维的大应变传感特性.导电纤维样品由化学气相沉积法制得;纤维的大应变传感特性实验在拉伸试验机下进行,同时记录下电阻随应变的变化.借助于SEM观测手段,得到了3种纤维的截面形状及纤维在加载条件下表面涂层形貌的微观图像,为分析纤维的...     

铌酸钾钠基透明上转换陶瓷材料制备及性能

采用热压烧结工艺, 以LiBiO₃作为烧结助剂, 制备了铌酸钾钠基透明上转换陶瓷K_0.5(1-y)Na_0.5(1-y)Li_yNb_1-yBi_yO₃- Er_0.005Yb_0.005x(Er³⁺/Yb³⁺:KNNLB, x=0~3, y=0~0.09)。并对其微观结构、光学透光率和上转换效应等进行了研究。结果表明该透明陶瓷具有正交钙钛矿型结构, 晶粒尺寸约0.5 μm, 致密度较高。该材料在红外区和可见光区有良好的透明性, 但是随着铒镱掺杂量的增加, 可见光区透光率呈明显的下降趋势。当y=0.06、x=0时, 在可见光范围内透过率可达到45%(样品厚度为0.5 mm), 红外光区域透过率达到95%以上。铒镱共掺杂透明陶瓷实现了在波长900 nm氙灯光源激发下的上转换效应。     

低In电解液电沉积制备CuInSe2吸收层

通过线性电位扫描分析了低In电解液中的阴极电化学反应,结果表明柠檬酸钠可以降低Cu2+的活性,而H2SeO3的加入可导致阴极上Se元素与Cu+和In3+发生复杂的协同反应.低In电解液中恒电位沉积的薄膜与CIS的化学计量比相差较大,分段电位的恒电位沉积得到的薄膜更接近于CuInSe2(CIS)化学计量比.薄膜在N2气氛上退火处理,得到了黄铜矿结构CIS薄膜,禁带宽度为1.06eV.     

心理授权与情绪智力对科研人员创新绩效的影响

目的探讨情绪智力与心理授权对科研人员创新绩效的影响机制。方法采用情绪智力、心理授权以及科研人员创新问卷,在科研团队中收集了128个团队中的333对上下级配对调查问卷数据。结果多层线性分析的结果表明心理授权对情绪智力与科研人员创新之间的关系具有中介作用。结论情绪智力对心理授权没有显著地正向预测作用;情绪智力可通过心理授权影响科研人员的创新绩效。     

非晶复合材料的半固态成形技术研究动向

综述了国内外非晶复合材料的制备与成形方法,特别对内生块体非晶复合材料的制备和成形技术的现状进行了分析,对内生块体增塑非晶复合材料半固体成形技术的研究动向进行了详细的介绍。最后,对内生块体非晶复合材料的半固体流变铸造成形技术进行了详细的论述和展望。     

Synergistic effect of various elements in Fe41Co7Cr15Mo14C15B6Y2 amorphous alloy hollow ball on catalytic degradation of methylene blue

Metallic glasses have recently attracted great attention in terms of degrading dyes and other organic pollutants as an environmentally friendly material for was...     

计及通信失效的输电系统信息物理协同恢复策略

为应对输电系统信息物理复合故障,提出了一种计及通信系统失效的信息物理协同恢复策略.首先,基于发电机、电力线路与负荷的故障特性,综合考虑了系统频率、节点电压、线路容量等安全约束,构建了物理系统的恢复模型.然后,提出了一种基于通信网络拓扑的信息系统恢复策略.接着,考虑信息系统故障给发电机出力调节、电力线路投运以及负荷恢复可...