EFFECT OF STRUCTURAL RELAXATION ON THE DEFORMATION BEHAVIOR OF A Zr64.13Cu15.75Ni10.12Al10 BULK METALLIC GLASS UNDER NANOINDENTATION

Structural relaxation by isothermal annealing below the glass transition temperature is conducted on a Zr64.13Cu15.75Ni10.12Al10 bulk metallic glass. The effect of structural relaxation on thermal and mechanical properties was investigated by differential scanning calorimetry and instrumented nanoindentation. The recovery of the enthalpy in the DSC curves indicates that thermally unstable defects were annihilated through structural relaxation. During nanoindentation, the structural relaxation did not have a significant influence on the serrated plastic flow behavior. However, Structural relaxation shows an obvious effect in increasing both the hardness and elastic modulus, which is attributed to the annihilation of thermally unstable defects that resulted from the relaxation

厌氧条件在不同Fe( II) 浓度测定方法中必要性的比较研究

厌氧是目前Fe(II)测定方法中常选择的处理方式,但是不可避免会给实验操作带来不便。为了方便、准确地测定铁还原体系中的Fe(II)浓度,对比研究了厌氧条件对草酸—草酸铵和盐酸两种典型浸提方法测定Fe(II)浓度的影响。结果表明:对于草酸—草酸铵浸提法,厌氧条件是必须的,以防止提取液中的Fe(II)被氧化,而且样品浸提1 h 便可用于Fe(II)的测定;然而对于盐酸浸提法,厌氧条件却并不是必须的,对Fe(II)浓度测定基本不产生影响。因此,为简化实验操作或在没有厌氧条件的情况,可利用盐酸浸提法测定铁还原体系中Fe(II)浓度

关于央行调控当前复杂经济的思考

当前央行面临的两大问题———通胀的可能和通缩的现实,为了解决这些问题,货币政策必须加以改善,利用再贴现再贷款、公开市场业务、存款准备金率这三大政策工具,并配合以货币政策之外的财政政策和金融政策加以调节

The scattering of general SH plane wave by interface crack between two dissimilar viscoelastic bodies

The scattering of general SH plane wave by an interface crack between two dissimilar viscoelastic bodies is studied and the dynamic stress,intensity factor at the crack-tip is computed. The scattering problem can be decomposed into two problems: one is the reflection and refraction problem of general SH plane waves at perfect interface (with no crack); another is the scattering problem due to the existence of crack. For the first problem, the viscoelastic wave equation, displacement and stress continuity conditions across the interface are used to obtain the shear stress distribution at the interface. For the second problem, the integral transformation method is used to reduce the scattering problem into dual integral equations. Then, the dual integral equations are transformed into the Cauchy singular integral equation of first kind by introduction of the crack dislocation density function. Finally, the singular integral equation is solved by Kurtz's piecewise continuous function method. As a consequence, the crack opening displacement and dynamic stress intensity factor are obtained. At the end of the paper, a numerical example is given. The effects of incident angle, incident frequency and viscoelastic material parameters are analyzed. It is found that there is a frequency region for viscoelastic material within which the viscoelastic effects cannot be ignored

Diffusion mechanisms in the Fe3ASi

In this paper, the possible reasons for the high thermal vacancy concentration and the low migration barriers for the Fe atom diffusion in the DO3 structure Fe3Si have been discussed

薄膜/基体的热失配致界面层裂研究

本文研究了热失配引起的残余应力作用下的薄膜/基体体系的界面层裂特征。假设薄膜和基体材料分别为弹塑性材料和弹性材料,薄膜/基体界面的层裂采用复合型的粘聚力模型来刻画。研究了对应不同薄膜材料参数和不同界面参数情况的界面层裂发生机制,给出了层裂发生时临界温度荷载与薄膜/基体几何参数、材料参数以及模型参数之间的关系

关于高等教育机构内外部管理者关系的研究

关于高等教育机构内外部管理者关系的研究厦门大学魏贻通，张建奇一、高等教育机构的举办者、办学者与行政管理者概念的界定1.举办者。所谓高等教育机构的举办者，指的是高等教育机构的创立者，或依法负责举办创立者所创立的高等教育机构的继任者，亦称高等教育机构的设..