Improved plasticity of iron-based high-strength bulk metallic glasses by copper-induced nanocrystallization

A significant enhancement in plasticity was achieved by the micro-addition of Cu in Fe-based bulk metallic glasses (BMGs) which have high strength at room-temperature. It was found that the nanocrystallization caused by the formation of the α-Fe phase is responsible for the improvement in plasticity of the Fe-based BMGs. Our results suggest that the micro-addition of Cu is a promising approach to enhancing the plasticity of Fe-based BMGs through compositional and structural design by microalloying.     

球形弹对金属靶板侵彻问题的数值模拟

基于球形空穴膨胀模型(SCE),采用ABAQUS有限元商业软件并结合自主开发的ABAQUS用户子程序对球形弹侵彻金属靶进行了有限元3D数值模拟。根据空穴膨胀理论,靶体对侵彻弹体的影响可以用一个作用在弹体表面的力函数代替,这样在进行数值模拟时就无需划分靶体网格,也避免了复杂的接触问题,从而使模拟大大简化。模拟过程中考虑到弹体的可变形性和入射时的微小偏航角,并且考虑了弹体在运动过程中和靶体的接触分离效应。模拟结果与文献中的实验结果进行了比较,模拟结果与实验结果吻合得很好。     

源于“团簇-共振”模型的理想金属玻璃电子化学势均衡

理想金属玻璃是指完全满足电子结构稳定性的金属玻璃. 在我们前期工作中提出的“团簇加连接原子"及理想金属玻璃的“团簇-共振"结构模型的 基础上, 本文指出理想金属玻璃应该满足电子化学势均衡判据, 可定量给出团簇与连接原子的比例, 最终确定了理想金属玻璃成分式[团簇](连接原子)_x. 运用此判据, 解析了Cu-Zr基和Co-B基块体金属玻璃, 实验确定的最佳形成能力成分满足电子化学势均衡.     

相干和非相干合成光束对金属瑞利粒子的光学俘获

研究了两光束的合成方式(相干和非相干合成)对俘获金属瑞利粒子的辐射力和稳定性的影响,着重研究了辐射力与合成方式、离轴距离、相干参数和粒子半径的关系.结果表明,不同合成方式下,离轴距离和相干参数都分别存在临界值d_c和α_c,在0d_c或α>α_c时,焦面处光强呈中心凹陷分布,此时横向梯度力不能作为回复力俘获金属瑞利粒子.在0<d≤d_c时,与非相干合成光束比较,相干合成光束在焦面处光强、辐射力、俘获刚性和纵向俘获范围更大.因此,适当选择合成方式,较小离轴距离和较低相干参数可有利于合成光束对金属瑞利粒子的俘获.     

退火态Zr55Al10Ni5Cu30块体非晶合金在轧制过程中的自由体积演化

将Zr₅₅Al₁₀Ni₅Cu₃₀块体非晶合金在715 K等温退火30 min, 引入少量纳米晶, 然后于室温以不同的应变速率进行轧制, 用差示扫描量热仪考察不同应变量样品的热稳定性和自由体积演化. 结果表明:即使轧制到95%的最大应变量, 样品的热稳定性也几乎没有发生改变. 在各种应变速率下, 随着应变量的增加, 自由体积含量持续上升. 但随着应变速率的增加, 相同应变量下自由体积的含量先上升后降低, 该规律与单一非晶态结构合金在塑性变形过程中自由体积的变化情况截然不同.     

Y对Fe-Si-B 合金非晶形成能力及软磁性能的影响

本文通过铜模吸铸法和单辊甩带法分别制备出一系列楔形试样和非晶条带试样, 系统研究了稀土金属Y对Fe₇₈Si₉B₁₃合金非晶形成能力及其软磁性能的影响. 结果表明, 少量Y取代 Fe-Si-B 非晶合金中的Fe 可大大提高该合金的非晶形成能力并促进过冷液相区的产生. 当Y含量为3 at.%时, 合金具有最大的非晶形成能力, 其临界厚度为313 μm, 相应的非晶过冷液相区宽度达到65 K. 该系列非晶合金具有优良的软磁性能, 其矫顽力(H_c)均低于200 A/m, Y含量为1 at.%时, 饱和磁感应强度(B_s) 达到最大值1.67 T.     

基于Fabry-Perot模型设计亚波长金属狭缝阵列光学异常透射折射率传感器

研究了在水溶液环境中亚波长金属狭缝阵列光学异常透射的折射率传感特性.采用严格的全矢量方法计算了狭缝阵列的透过率谱.建立了Fabry-Perot半解析模型,能够精确预言全矢量方法的计算结果.基于该模型给出的共振条件,提出并解释了当透射峰精确位于瑞利异常位置时,透射峰能达到最尖锐的状态,给出了设计狭缝阵列达到该状态的方法.设计得到的透过率谱峰值半高宽δλ可达0.01 nm,对应的溶液折射率测量不确定度δn_s达到2×10^-6RIU.系统地给出了阵列周期、狭缝宽度、入射角等参数对设计得到的传感灵敏度,δλ,δn_s,峰值透过率等的影响.     

点簧簧片振动特性数值分析

簧片是笙等中国传统簧管类乐器的核心部件之一.通过点簧工艺可调整簧片振动频率,点簧簧片的差异对整体乐器的声音效果具有重要影响.针对点簧簧片的振动特性问题,对其建立非均匀截面并具有质量负载的振动模型,采用有限元方法计算点簧簧片的固有频率.大量算例分析了点簧质量、位置以及簧片的边界条件对振动频率的影响,研究发现:若点簧质量不...     

Sensitive determination of diuron on zinc oxide nanoparticles modified carbon paste electrode in soil and water samples

An electrochemical sensor based on Zinc oxide nanoparticles (ZnONPs) modified carbon paste electrode was designed for the toxic diuron pesticide detection. The ZnONPs were synthesized through the hydrothermal route and their structural properties were investigated via scanning electron microscopy (SEM) and X-ray diffraction powder (XRD). The designed ZnONPs-modified carbon paste electrode (ZnONPs-CPE) was characterized using cyclic voltammetry and electrochemical impedance spectroscopy. The sensor showed significantly enhanced sensitivity on the diuron oxidation peak current, compared to the bare carbon paste electrode. Qualitative and quantitative analysis were performed using cyclic voltammetry (CV) and square wave voltammetry (SWV). Experimental parameters such as pH, amount of ZnONPs and frequency were evaluated and the optimized conditions were obtained with 0.1 M phosphate buffer solution at pH=8, a frequency of 50 Hz and a quantity of 5 mg of ZnONPs. Under these conditions, linear responses ranging from 1.3 to 7.7 μM and 8.6 to 30 μM of diuron were obtained, with correlation coefficients of R²=0.994 and 0.996 respectively. Detection and quantification limits of 0.22 μM and 0.84 μM (S/N=3) were respectively achieved based on the 3σ method. The interference of some ions on the oxidation peak of diuron on ZnONPs-CPE was also evaluated and no interference was observed, therefore demonstrating the selectivity of the sensor. The proposed sensor, designed with ecofriendly materials, is sensitive, selective and was effectively used for diuron determination in soils and water samples with recoveries ranging from 98 % to 101.5 %.