定向凝固 NiAl/Cr(Mo,Hf)合金的微观组织及力学性能

研究了定向凝固NiAl-28Cr-5.85Mo-0.15Hf合金的微观组织与在293～1373K温度范围内的力学性能.结果表明:合金是由NiAl枝晶轴和枝晶间区(NiAl和Cr(Mo)相的共晶)组成的.经过长期固溶时效处理NiAl/Cr(Mo)合金析出少量弥散分布的Huesler相,其余Hf以固溶体方式存在.DSNiAl-28Cr-5.85Mo-0.15Hf合金具有明显的韧脆转变行为,韧脆转变温度依赖于应变速率.室温拉伸断口呈现明显的解理断裂,而韧脆转变温度在以上时,合金具有较大的变形量,断口上有许多韧窝,呈现明显的塑性断裂特征.     

EB—PVD制备微晶Ni-11．5Cr-4．5Co-0．5Al合金薄板800℃氧化行为研究

对EB—PVD制备微晶Ni-11．5Cr-4．5Co-0．5Al合金薄板在800℃空气中氧化行为进行研究，采用SEM对氧化试样的表面和截面形貌进行研究，小角XRD和EDAX对其相和成分分布进行分析。氧化物主要由NiO，Ni（Al，Cr）2O4和Cr2O3组成，在长时间氧化后在氧化物和基体界面出现Al2O3内氧化层；细晶Ni-11．5Cr-4．5Co-0．5Al合金氧化动力学符合立方规律而非抛物线规律；与粗晶材料相比，细晶材料氧化产物晶粒细小，其高密度的晶界成为短路扩散的途径。     

Fe-Cr-Co-Mo合金的穆斯堡尔效应的研究

应用穆斯堡尔谱学方法半定量测定了Fe-Cr-Co-Mo永磁合金在最佳磁性状态两相的成分及相对量。Fe-23Cr-15Co-2Mo-0.5Ti柱晶合金和Fe-30Cr-25Co-3Mo-1Ni-0.5Zr等轴晶合金的a_1相分别为78Fe-18Co-4Cr和60Fe-37Co-3Cr。a_2相分别为12Fe-3Co-85Cr和9Fe-3Co-88Cr,a_1相的相对量分别为0.72和0.62。结合透射电子显微镜,磁转矩仪和冲击磁测仪测定了合金中强磁性相粒子的尺寸,单轴各向异性常数和合金矫顽力等磁性能参数。按单畴粒子理论计算了合金的矫顽力,所得结果与实测值符合较好,从而认为Fe-Cr-Co-Mo合金的高矫顽力来自于单畴粒子的磁矩转动。     

NiAl-28Cr-5.94Mo-0.05Hf-0.01Ho定向共晶合金的高温氧化行为

在900-1150℃氧化的NiAl-28Cr-5.94Mo-0.05Hf-0.01Ho定向共晶合金,在其表面生成了连续的Al_2O_3氧化膜,具有良好的抗氧化性能。定向凝固工艺使合金的组织细化并提高了Cr(Mo)相中Al元素的含量,以及加入微量稀土元素Ho,都有利于生成Al_2O_3氧化膜。在NiAl-28Cr 5.94Mo-0.05Hf-0.01Ho定向共晶合金的氧化过程中表面氧化膜发生相变θ-Al_2O_3→α-Al_2O_3,导致其1000℃氧化质量增加出现反常。     

Ni-34Mo-0．5Si—Zr无磁定膨胀合金的焊接性能

Ni-34Mo-0．5Si—Zr合金是我所近年研制的一种电真空系统用新型无磁定膨胀合金封接材料，同时，该合金也是良好的耐腐蚀材料，本文研究了Ni-34Mo-0.5Si—Zr合金的可焊性，经钨极氩弧焊表明，Ni-34Mo-0．5Si—Zr合金焊接工艺简便可靠，焊接流动性和成形性良好，焊接组织细小致密，焊接裂纹倾向性小，Ni-34Mo-0．5Si—Zr合金焊接后仍具有良好的塑性和韧性。     

WC-9Ni-0．57Cr硬质合金在模拟海水中的腐蚀特性

以WC-9Ni-0．57Cr硬质合金为研究对象。采用失重法、电化学测试、力学性能测试和显微形貌分析等方法,研究合金在3．5％NaCl模拟海水溶液中的腐蚀行为,并与传统的WC-6Co硬质合金进行了比较。结果表明：在3．5％NaCl溶液中室温腐蚀8周的WC-9Ni-0．57Cr合金与WC6Co合金的腐蚀速率分别为0．0033mm／a和0．0072mm／a,以Ni—Cr为粘结相制备的硬质合金耐腐蚀性能明显优于传统的WC—Co硬质合金,具有较强的抗腐蚀能力;硬质合金微观腐蚀形态表现为粘结相的腐蚀,使力学性能降低,室温腐蚀4周后WC-9Ni-0．57Cr合金与WC-6Co合金的横向断裂强度损失率分别为8．43％和31．14％。     

不同Cr含量的Ni基合金电化学腐蚀行为

利用电化学测试技术研究不同Cr含量的Ni基合金耐Cl-离子水溶液腐蚀的能力。结果表明：Ni基合金耐Cr离子腐蚀性能随着合金中Cr含量的提高而增强,溶液中Cl-离子浓度对Ni-9Cr、Ni-15Cr和Ni-20Cr合金有较大影响,特别是Ni-9Cr合金在0．6mol／LNaCl溶液中腐蚀最为严重,而对于Ni-25Cr和N...     

Effect of 0.1 wt pct Dy Addition on Morphology and Compressive Behavior of Cast NiA1-28Cr-5.SMo-0.2Hf

Effect of 0.1 wt pct Dy addition on microstructure and compressive behavior of NiAl-28Cr-5.8Mo-0.2 Hf eutectic alloy was investigated. The results showed that remarkable lamellar refinement can be achieved with the addition of 0.1 wt pct Dy. The Dy addition results in the decrease in Young＇s modulus of alloy and the.enhancement of the compressive strength and ductility of alloy at all testing temperatures. The lamellar refinement, the increased dislocation networks located at the interfaces of NiAl/Cr（Mo） and the strengthening of cell boundary are benefical to the improvement of compressive properties of the alloy.     

Ti含量对NiAl-Cr(Mo)共晶合金凝固组织的影响

添加Ti降低了NiAl-Cr(Mo)共晶合金凝固过程中NiAl/Cr(Mo)共晶生长速度,导致NiAl/Cr(Mo)胞状共晶组织的粗化,并因合金偏离共晶成分而促进先共晶NiAl相的形成.在添加Ti的NiAl-Cr(Mo)共晶合金中,Ti主要分布在基体NiAl相中.随着Ti含量的提高,过饱和的NiAl(Ti)基体发生分解,促进了Ni2AlTi相的形成,并且NiAl/Cr(Mo)胞状共晶组织发生退化.Ni-33Al-28Cr-3Mo-5Ti共晶合金的NiAl基体中析出细小的Cr(Mo)相,Cr(Mo)共晶相中析出细小的NiAl相.     

纯铁在750℃熔融LiCl-Li2O中的腐蚀行为

利用锂化还原技术处理乏燃料时,形成了LiCl-Li2O混合熔盐,这将造成反应容器和传送装置材料的加速腐蚀.为了解此类腐蚀的腐蚀机理,采用浸没法腐蚀实验研究了纯铁在750℃不同含量熔融LiCl-Li2O中的腐蚀行为.腐蚀产物的相结构采用X射线衍射(XRD)分析,用电子探针(EPMA)观察截面形貌和分析腐蚀产物的元素分布.实验结果表明,随着Li2O含量的增加,纯铁在750℃熔融LiCl-Li2O中的腐蚀产物发生了由LiFe5O8向LiFeO2的转变,这与热力学计算得到的相稳定图一致,同时腐蚀减重随Li2O含量的升高而增大.Li2O含量是影响纯铁在熔融LiCl-Li2O中腐蚀行为的决定性因素.     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

From Industry 4.0 to Research 4.0. Development of High Performance Fibers in the Light of Digitization

We associate a variety of innovations with the term ＂Industry 4.0＂. The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

Roman iron and steel: A review

ABSTRACT

The production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...