液相对流对固液界面稳定性的影响

以模型合金丁二腈－乙醇的强制性晶体生长为基础，利用自行研制的液相对流驱动装置，详细考查了液相自然对流及强迫对流作用下，模型合金平界面失稳的动态生长过程，证实了液相的流动加快了液相温度与浓度分布的均匀化，从而增强了液／固界面的稳定性。并且随流动速度的增加，界面稳定性提高。     

定向凝固镍基高温合金DZ17G的持久寿命

分析了定向凝固镍基金高温合金DZ17G在广泛应力范围（105-950MPa）内的高温（650-980℃）持久实验数据。结果表明，在同一温度下，合金的持久寿命与施加应力间的关系符合半对数规律，可以利用Manson-Succop系数法对短期实验数据进行外推，以预测长期持久寿命。给出了DZ17G合金的持久方程及热强参数综合方程，预测值与实测值得很好符合。     

DZ125定向凝固高温合金在不同状态下的超高周疲劳行为研究

研究了常规热处理和长期时效状态的DZ125定向凝固高温合金在室温和700℃下的超高周疲劳特征及其差异。利用超声疲劳试验机测试了合金的超高周疲劳性能,采用扫描电镜研究了合金的疲劳断口特征,借助电子探针和纳米压痕测量仪分别测试了合金枝晶间和枝晶干的成分和弹性模量。结果表明:两种热处理制度下DZ125合金的枝晶间和枝晶干的弹性模量以及合金元素分配和偏析比差异不大;DZ125合金在700℃下的超高周疲劳性能低于室温,合金在室温下存在明显的频率效应,但在700℃下不存在频率效应;室温和700℃下,合金经过长期时效后的疲劳性能均有所降低,特别在700℃下合金性能降低得更多。室温下,DZ125合金的两种热处理制度的超高周疲劳裂纹均起源于试样的表面;700℃下,两种热处理制度的超高周疲劳裂纹均起源于试样的亚表面。     

Si-TaSi2共晶自生复合场发射材料的定向凝固组织特征

采用电子束悬浮区熔装置（EBFZM）制备了Si-TaSi2共晶自生复合场发射材料,系统地研究了Si-TaSi＋2共晶的定向凝固组织特征.当凝固速率在0.3～9.0mm/min范围内变化时,均可获得Si-TaSi2共晶自生复合材料,具有高精确取向的TaSi2纤维在硅连续基体中均匀分布.随着凝固速率的增大,TaSi2纤维的直径和平均间距减小,面密度和体积分数增大.采用零功率法考察了不同凝固速率时的固-液界面形貌.当凝固速率由0.3mm/min变化到5.0mm/min时,固-液界面经历了平界面→浅胞状界面→胞状界面→平界面的演化过程.     

Fractal Description of the Shearing-Surface of Tools

In this paper, the basic methods are introduced to calculate the fractal dimensions of the shearing surface of some tools. The fractal dimension of the shearing surface of experimental sampling is obtained and the fractal characteristics are also discussed. We can apply the fractal method to identify types of tools used by burglars and to do the job of individual recognition. New theories and methods are provided to measure and process the shearing surface profile of tools.     

Al-Fe液/固复合界面扩散溶解层研究

采用镶嵌式扩散偶技术制备了Al-Fe扩散偶,在Al熔点以上Fe熔点以下进行扩散热处理,研究了Al-Fe液/固界面扩散溶解层的组织结构演变、形成机理及生长规律。实验结果表明,Al-Fe扩散偶扩散热处理后的组织结构为Al+FeAl3/FeAl3/Fe2Al5/Fe;Fe2Al5层是保温过程中第一个出现的也是唯一出现的连续单相层,FeAl3层则是在冷却过程中形成;Al基中存在针状的和条状的FeAl3析出相,从界面附近到远离界面,析出相的密集程度和尺寸都逐渐小;在相同的保温时间下,热处理温度与扩散溶解层厚度之间存在指数关系;在相同的热处理温度下,保温时间与扩散溶解层厚度偏离抛物线关系。     

短时氧化对定向凝固高温合金不同取向腐蚀性能的影响

为了研究定向凝固高温合金不同取向氧化前后的常温腐蚀性能,选择镍基高温合金DZ125和钴基高温合金DZ40M在1050℃下进行不同时间的短时氧化,研究合金不同取向的氧化行为;对氧化前后合金在3.5%NaCl溶液中进行电化学实验,研究氧化对定向凝固高温合金不同取向常温腐蚀性能的影响。结果表明:定向凝固高温合金晶界或亚晶界附近容易发生局部腐蚀,纵截面晶界和亚晶界面积分数小,因此耐蚀性优于横截面;与合金横截面相比,纵截面晶界结构不利于扩散,故其氧化速率小于横截面;短时氧化后在合金表面生成分层结构的氧化物,对合金起到保护作用,一定程度上提高耐蚀性。     

一种测定定向凝固工艺参数的方法

利用连续测定试样顶面温度的方法，方便地测定了向凝固时的温度梯度以及固液界面位置，发现温度梯度受抽拉速度的影响不大，而固液界面的位置抽拉速度影响较大，随着抽拉速度的增大，固液界面位置向下移动。     

An Experimental Technique for Liquid/Solid Thermal Conductivity Measurements at the Melting Point

Based upon the theory that the thermal conductivity can be determined by measuring the speed of the propagation of the solid/liquid phase interface during a phase transition, a system was developed to investigate the thermal conductivity of metals and alloys at the liquid/solid phase transformation point. Furthermore, a mathematical method was applied to represent the melting and solidifying process in the phase transformation chamber, by which the error could be analyzed. In order to test the feasibility of the method and the measuring system, a series of verification experiments on lead have been performed to estimate the precision and the applicability of the measuring system. From comparisons with recommended data from the literature, the uncertainty of the experimental results is estimated to be about 5% which means the measuring method is suitable to determine the thermal conductivity of eutectic alloys and metals at the liquid/solid phase transformation point. This work provides a relatively precise method for thermal conductivity measurements on new materials such as lead-free solders.Paper presented at the Seventh Asian Thermophysical Properties Conference, August 23–28, 2004, Hefei and Huangshan, Anhui, P. R. China     

Ti/Al比对镍基定向高温合金组织和性能的影响

用金相显微镜和扫描电镜对镍基定向高温合金铸态及热处理态的组织进行观察和分析,用透射电镜的EDS对合金元素在γ和γ~′两相中的分配比进行测试和分析,研究了在Al+Ti质量总和相同条件下,Ti/Al比对其微观组织及持久性能的影响。结果表明:随着Ti/Al比的增加,合金铸态组织中共晶含量显著增加,共晶周围有η相生成;合金初熔温度降低;相同热处理条件下,γ′相的尺寸增加,立方度降低;合金持久性能变化不大。     

加Re新型单晶高温合金熔体与Al2O3型壳界面状况研究

对加入Re的新型单晶高温合金与Al2O3型壳之间的界面状况进行了研究。结果表明，在1550℃下，熔融的合金液体不会与Al2O3型壳产生反应，Al2O3型壳是与DD3+2Re(wt%)新一代单晶配合良好的材料。，The boundary condition between Al2O3 mould shell and a new type single crystal superalloy has been investigated. The results show that the melted superalloy does not react with Al2O3 mould shell,and the Al2O3 mould shell is a good kind of material to match the DD3+Re(2%wt) superally.     

稀土影响高温合金GH907性能的显微机理研究

研究了稀土对GH907合金的力学和物理性能的影响规律,优化了可善GH907合金缺口持久性能,高温抗氧化性能的合金体系,通过比较标准GH907合金和稀土GH907合金的显微组织和界面结构,提出了稀土提高合金性能的微观机理,稀土主要存在于合金的片状相中,使其含量,形态,分布和晶体结构发生改变,与基体之间界面晶格失配和界面应力大小大减小。     

两种不锈钢在单相流和液/固两相流中冲刷与腐蚀的交互作用

用质量损失法研究了65Mn和316L及其Ni-P镀层的冲刷腐蚀行为.结果表明:在试样表面与流体间相对运动距离相同的条件下,65Mn和316L在单相流和两相流中的冲刷腐蚀速率随着介质温度的升高和理论流速的减小而增大.在20%H2sO4单相流和20%H2S04+20 g/L黄砂两相流(50℃,L88 m/s)中,冲刷与腐蚀...     

矩形贮箱类液固耦合系统的随机响应

针对于常重力下矩形贮箱类液固耦合系统受到俯仰激励情形 ,本文通过两种不同形式的Lagrange函数建立了系统耦合动力学方程 ,研究了该耦合系统在随机激励下的响应 ,求得波高响应的功率谱及均方值。对于一个算例 ,讨论了该液固耦合系统的动力特性     

First-Principles Study of the Polar TiC／Ti Interface

The interface structure, work of adhesion, and bonding character of the polar TiC/Ti interface have been examined by the first-principles density functional plane-wave pseudopotential calculations. Both Ti- and C-terminated interfaces including six different interface structures were calculated, which present quite different features. For the Ti-terminated interface, the interfacial Ti-Ti bond has a strong metallic and weak covalent character; while for the C-terminated interface, the interfacial bond is a strong polar covalent interaction between the Ti-3d and C-2p orbital.The work of adhesion of C-terminated interface is nearly 9 J/m2 stronger than that of the Ti-terminated. It is found that each termination has relatively large work of adhesion, which is consistent with other polar interfaces.     

Capturing Solvation Effects at a Liquid/Nanoparticle Interface by Ab Initio Molecular Dynamics: Pt201 Immersed in Water

Solvation can substantially modify the adsorption properties of heterogeneous catalysts. Although essential for achieving realistic theoretical models, assessing such solvent effects over nanoparticles is challenging from a computational standpoint due to the complexity of those liquid/metal interfaces. This effect is investigated by ab initio molecular dynamics simulations at 350 K of a large platinum nanoparticle immersed in liquid water. The first solvation layer contains twice as much physisorbed water molecules above the terraces, than chemisorbed ones located only at edges and corners. The solvent stabilizes the binding energy of chemisorbates: 66% of the total gain comes from interactions with physisorbed molecules and 34% from the influence of bulk liquid.     

热处理对新型Ni-Fe基高温合金烟灰/气腐蚀行为的影响

以针对700℃超超临界燃煤锅炉用高温耐热材料而开发的一种新型Ni-Fe基合金为研究对象,利用扫描电子显微镜(SEM),能谱分析(EDS)及X射线衍射(XRD)等方法分析合金组织结构、腐蚀产物形貌、元素分布和腐蚀产物物相,研究两种热处理制度对合金在模拟锅炉烟灰/气环境中高温腐蚀行为的影响。结果表明,750℃腐蚀500 h后,两种热处理试样表面氧化膜结构完整,腐蚀产物基本一致,主要为富Fe、Cr氧化物,另有少量Al2O3、Ti O2及Ti、Mo的内硫化腐蚀产物,但截面腐蚀形貌差异较大。由不同热处理造成的合金组织结构的变化影响了合金的腐蚀速率,腐蚀前400 h内,1#试样氧化膜较厚,腐蚀增重较大,400 h后,沿晶界内腐蚀现象的加剧导致2#试样的腐蚀增重曲线与1#趋于一致。     

Characterisation of steel/nickel bronze clad strips prepared by continuous solid/liquid bonding method

A continuous solid/liquid bonding method was successfully developed to fabricate Cu–10wt-%Ni–1wt-%Fe (nickel bronze) clad steel with a good metallurgical bonding in the present study. The results indicated that the diffusion distance of interface is about 1.90–2.18?µm. The average tensile shear strength of centre composite strip at as-cast state is 228?±?5?MPa, while that of edge is 202?±?6?MPa, and the interface strength is higher than that of bronze since the fracture always occurs on the nickel bronze side. After the rolling process, the tensile shear strength increases with the increasing rolling reduction. The reason can be ascribed to the strengthening of the nickel bronze whose strength is still lower than the interface.     

表面活性剂对固相反应制备钴酸镍形貌影响的研究

采用醋酸镍、醋酸钴和草酸，加入不同的表面活性剂，在室温条件下进行固相化学反应，于60℃水浴恒温2d，获得前驱物；经热分析后，610℃分解．用XRD、SEM对热分解产物进行表征，获得了多种不同微观形貌的NiCo2O4复合氧化物．进行了不同聚合度和不同类型的表面活性剂对多种制备体系产物形貌影响的对比实验．实验结果表明，表面活性剂在合成过程中充当了软摸板剂，对产物形貌的构成产生了明显作用．