高比重钨合金力学性能影响因素分析

首先考虑液相烧结工艺条件及组分对高比重钨合金微结构和各相性质的影响，再从细观力学的角度考虑高体积百分比钨合金微结构及各相性质对复合材料有效力学性质的影响，从而架起工艺条件及组分与钨合金力学性能之间关系的桥梁，为分析高比重钨合金性能从理论上建立一套方法，从材料设计和制备的角度实现对这种材料性能优化提供一种方案。并应用上述模型和方法对用粉末冶金法制备的两种不同钨含量的钨合金材料微结构和力学性能进行分析。     

钨合金细观参数对其宏观屈服强度的影响

通过细观分析,给出钨颗粒相的形状、组分和两相力学参数对钨合金宏观屈服强度的影响.其中,钨颗粒看作基体上的夹杂,在小变形条件下假设钨颗粒仅发生弹性变形,而钨合金的宏观屈服强度决定于基体相的屈服强度.在该假设基础上,利用Eshelby方法及Mori-Tanake平均应力概念计算分析了不同钨合金材料,特别是不同变形量工艺处理的钨合金材料的宏观屈服强度,计算结果与实验结果基本一致.     

液力挤压法制备新型钨合金穿甲弹芯材料技术

采用液力挤压法制备新型钨合金穿甲弹芯材料,较常规钨合金材料变形加工技术相比,其最大优势是仅通过一次变形可使钨合金材料的性能得到大幅度提高.可对现役、在研各口径、各长细比钨合金穿甲弹进行技术改造和移植.为钨合金穿甲弹芯材料的变形加工提供新的有效技术途径.     

反向法确定钨合金基体细观性能及其宏观验证

为了确定钨合金基体相的细观性能,采用纳米压痕实验测试了钨合金材料中基体相的细观硬度与弹性模量.利用反向确定法给出了钨合金材料中基体相的细观弹、塑性性质,根据纳米压痕实验中得到的载荷-位移关系,通过三维有限元计算给出了基体相的原位细观屈服强度和硬化模量.为探讨反向法确定钨合金基体细观性能的有效性,采用宏观实验给出了其宏观验证.宏观验证结果表明,用反向法确定钨合金基体材料的细观弹、塑性性质是可靠的.     

均质钽2.5钨合金加工工艺研究

采用"锻造+多向轧制"工艺,研究了均质钽2.5钨合金材料在不同方向、不同部位和不同热处理工艺条件下的拉伸性能和显微组织,最终确定了均质钽2.5钨合金的加工工艺。     

电沉积钨及钨合金涂层的研究进展

金属钨及含钨涂层具有优良的性能,如高熔点、高硬度、良好的化学稳定性和较低的热膨胀系数,在多个领域被广泛应用,金属钨及含钨涂层有很多制备方法,其中电沉积法具有重要的地位。综述了熔盐电沉积钨涂层及溶液电沉积钨合金涂层的研究进展,并展望了熔盐电沉积钨涂层及溶液电沉积钨合金涂层的发展趋势。     

液力挤压钨合金的微观破断特征及变形强化机制

研究了93钨合金材料不同液力挤压的微观破断过程及变形强化机制.结果表明,裂纹的扩展首先萌生于合金中最薄弱的部位,即钨颗粒与钨颗粒的界面之间.随着挤压变形量的增大,裂纹的传播途径由粘结相向钨颗粒转移,所带来的最终效果是微观组织的"纤维化"和钨颗粒的穿晶解理比例越来越大,最终导致钨合金整体强度不断提高.同时在挤压过程中,合金组成相中的位错密度随变形量的增加而不断增大,钨颗粒与粘结相及钨颗粒之间的界面成为位错滑移的障碍,位错在滑移过程中遇到界面的障碍而不断地塞积,导致W-M界面结合强度及W-W界面结合强度增大,最终使得合金的变形抗力增大,合金的强度增大.     

钨及钨合金的镀前处理和镀层结合力的探讨

钨及钨合金的镀前处理和镀层结合力的探讨南京航空航天大学材料科学与工程系（２１００１６）袁卫兵１前言钨及钨合金是一种耐高温材料，具有优异的屏蔽射线功能，在各工业领域中应用较广。钨及钨合金在高温下易氧化，对基材无防护能力，因而其应用又受到了一些限制。如果...     

钨合金材料的动态拉伸实验研究

采用旋转盘式间接杆-杆型冲击拉伸装置(SHTB)对颗粒度分别为2, 5μm和20μm的三种91%(质量分数)细化钨合金材料在动态冲击载荷作用下的力学性能进行了实验研究,分析了三种钨合金在应变率为0.001, 200, 500s-1时动态力学性能,给出了颗粒度大小与材料屈服强度的关系;采用扫描电子显微镜(SEM)对动态拉伸实验中回收的试件断口进行断口分析,研究钨合金在不同应变率状态下材料的破坏特征,在动态拉伸载荷作用下钨合金材料呈现出一种混合破坏模式包括钨颗粒的劈裂以及颗粒与基体界面的开裂.     

钨银复合材料的应用与研究进展

简要介绍了国内外钨银材料的传统工艺和制备新技术,对具有良好导热、导电和高温抗氧化等优良性能的钨银复合材料在电气工程、机械加工、集成电路及国防军工等方面的应用进行了综述。最后对纳米钨银复合材料的制备技术和应用研究进行了展望。     

检定和校准证书的异同与应用

本文介绍了检定和校准以及证书的两点相同、五点不同之处,说明了对检定证书和校准证书的正确应用。     

Synthesis and luminescent properties of alkali-metal and ammonium fluorosulfatozirconates and fluorosulfatohafnates

We have synthesized a variety of alkali-metal and ammonium fluorosulfatometallates (titanates, zirconates, and hafnates). The alkali fluorosulfatozirconates and fluorosulfatohafnates have been shown to exhibit efficient roentgenoluminescence (RL) in the UV through visible spectral region, with a maximum at 390–440 nm. Their RL spectra depend significantly on their composition (cation, anion, and water content), coordination of KF and K₂SO₄, and relative amounts of fluorine and SO₄ groups. We have examined the effect of heat treatment on the RL of these compounds. The rubidium and cesium fluorosulfatozirconates Rb₃Zr₂F₉SO₄ · 2H₂O, Cs₂ZrF₂(SO₄)₂ · 2H₂O, Cs₈Zr₄F₂(SO₄)₁₁ · 16H₂O, and Cs₂ZrF₄SO₄ offer the most efficient RL.     

The shape and stability of wall-bound and wall-edge-bound drops and bubbles

The behavior of wall-bound drops and bubbles is fundamental to many natural and industrial processes. Key characteristics of such capillary systems include interface shape and stability for a variety of gravity levels and orientations. Significant solutions are in hand for axisymmetric pendent drops for a variety of uniform boundary conditions along the contact line with gravity acting normal to a planar wall. The special case of a wall-bound drop or bubble that is also pinned at an edge (i.e. a ‘wall-edge-bound’ drop) is considered here where numerical solutions are obtained for interface shape and stability as functions of drop volume, contact angle, fluid properties, and uniform gravity vector. For a semi-infinite zero-thickness planar wall (plate), a critical contact angle is identified below which wall-edge-bound drops are always stable. The critical contact angle is computed as a function of the gravity vector. The numerical procedure, which makes no account for contact angle hysteresis, predicts that such wall-edge-bound drops are unconditionally unstable for any gravity field with a component that is tangent to the wall while inwardly normal to the edge. Select experiments are conducted that support the conclusions drawn from the numerical results.     

凝固科学技术与材料

从凝固科学与实践发展的角度介绍了当前凝固材料体系的基本框架和凝固科学主要发展阶段的基本理论。作为材料科学与工程的基本组成，凝固科学技术正在现代科学理论的基础上针对传统材料的改性提高和新材料的发展需求，以控形、控构、控性为目标开展优质铸件的定向、晶体生长、快凝、深过冷及各种新型和超常领域凝固过程的研究，并介绍了其中某些方面和展望了可能的发展趋势。     

Heat and Mass Transfer and Modeling and Prediction of Environmental Catastrophes

Basic definitions and concepts of the physicomathematical theory of natural catastrophes are given. Possibilities of mathematical modeling of natural and technogenic catastrophes are discussed in the context of the theory of heat and mass transfer and the mechanics of reacting media. The importance of taking into account conjugate heat and mass exchange in modeling catastrophes is emphasized. A formula for evaluating the probability of a collisional catastrophe is given.     

Multi-ferroic and magnetoelectric materials and interfaces

The existence of multiple ferroic orders in the same material and the coupling between them have been known for decades. However, these phenomena have mostly remained the theoretical domain owing to the fact that in single-phase materials such couplings are rare and weak. This situation has changed dramatically recently for at least two reasons: first, advances in materials fabrication have made it possible to manufacture these materials in structures of lower dimensionality, such as thin films or wires, or in compound structures such as laminates and epitaxial-layered heterostructures. In these designed materials, new degrees of freedom are accessible in which the coupling between ferroic orders can be greatly enhanced. Second, the miniaturization trend in conventional electronics is approaching the limits beyond which the reduction of the electronic element is becoming more and more difficult. One way to continue the current trends in computer power and storage increase, without further size reduction, is to use multi-functional materials that would enable new device capabilities. Here, we review the field of multi-ferroic (MF) and magnetoelectric (ME) materials, putting the emphasis on electronic effects at ME interfaces and MF tunnel junctions.