超细晶粒硬质合金复合粉的成形特征

采用沉降分离，高能剪切粉碎，比表面分析（BET）和扫描电镜（SEM）观察等手段研究了超细硬质合金粉末中的桥接团粒在分离，破碎过程中，松装密度和比表面的变化，研究和对比了常规湿磨、高速搅拌球磨、高速剪切粉碎对粉末成形致密化曲线的影响。结果表明：桥接团粒可被高速剪切粉碎机有效地粉碎。粉末的松装密度成倍地增长，并且压坯的相对密度由33．5％增加到60％。     

Investigation on RQ Embrittlement Mechanism of FeCuNbSiB Soft Magnetic Alloy

ＳｉｎｃｅｔｈｅｎａｎｏｃｒｙｓｔａｌｌｉｎｅｓｏｆｔｍａｇｎｅｔｉｃａｌｌｏｙＦｅ73 .5Ｃｕ1Ｎｂ3Ｓｉ13 .5Ｂ9ｗｉｔｈｅｘｃｅｌｌｅｎｔｓｏｆｔｍａｇｎｅｔｉｃｐｒｏｐｅｒｔｉｅｓｗａｓｄｅｖｅｌｏｐｅｄｂｙＹｏｓｈｉｚａｗａＹｅｔａｌｉｎ1988[1] ,ｉｔｓｍａｇｎｅｔｉｃｔｈｅｏｒｙ ,ｃｈｅｍｉｃａｌｃｏｍｐｏｓｉｔｉｏｎ ,ｐｒｅｐａｒａｔｉｏｎｔｅｃｈｎｏｌｏｇｙ ,ｓｔｒｕｃｔｕｒｅａｎｄｔｒａｎｓｉｔｉｏｎａｓｗｅｌｌａｓｓｐｒｅａｄｉｎｇａｐｐｌｉｃａｔｉｏｎｗｅｒｅｓｔｕｄｉｅｄｅｘｔｅ…     

Present Technology of Hard and Soft Ferrites

Abstract

In order to improve the mechanical properties of cemented carbides, Ti(C,N)–Ni–Mo alloys, in which carbon in the titanium carbide is replaced by nitrogen, are of potential interest from the viewpoint of grain size control. Since grain size control by nitrogen was also observed in Ti(C,N)–Ni alloys containing no molybdenum, the effect of nitrogen on grain growth of Ti(C,N)–Ni alloys was investigated by comparing TiC–Ni and TiN–Ni alloys. The grain growth rate of Ti(C,N)–Ni alloys showed a minimum value at the carbon content C/C+N = 0·5. From the results of chemical and grain size analyses, it is considered that the growth rate depends on the solubility of Ti(C,N) in the nickel solid solution and the degree of coalescence because the solubility decreases with decreasing carbon content. With nitride, the amount of liquid increases by denitrification of TiN, owing to the formation of the nickel solid solution or TiNi₃ phases, and growth of TiN grains by Ostwald ripening is observed. The apparent activation energy for the growth of TiC and TiN grains is calculated to be ～4·4×10⁵ and 1·9 × 10⁵ J mol^?1 respectively. PM/0201     

软硬FeSi75%交叉冶炼法

分析了小电炉冶炼硬７５硅铁效率低下的原因，提出了具体改进措施和所取得成果。     

The Influence of Grain Boundary Phosphorus Concentration on Liquid Metal and Hydrogen Embrittlement of Monel 400

The susceptibility of Monel 400® to embrittlement by mercury and by hydrogen was measured as affected by thermal treatment. Specimens were annealed at 900°C and either quenched or furnace cooled. Auger analysis revealed phosphorus segregated to the grain boundaries; furnace cooling causes the boundary concentration to be about twice that of the quenched material. Tensile tests were conducted with specimens (1) in air, (2) coated with mercury, or (3) cathodically precharged with hydrogen. Fractures in air were completely ductile, and ductility was not affected by thermal treatment. Fractures of mercury-coated and hydrogen-charged samples were brittle and intergranular; elongation to fracture increased significantly with increasing concentration of grain boundary phosphorus. The results are discussed in terms of additive and interactive mechanisms.     

A Review of Liquid Metal Embrittlement: Cracking Open the Disparate Mechanisms

Metallurgical and Materials Transactions A - Liquid metal embrittlement (LME) is the term for a collection of phenomena by which the action of a liquid metal in contact with the surface of a solid...     

The Creep-Rupture Embrittlement of Copper

Abstract

The process of gas phase sulphation of NiO and CO₃O₄ is normally hindered by a protective coating of the sulphate on the oxide, but the reaction can be catalyzed by the addition of small amounts of alkali metal sulphates. Experiments done with Na₂SO₄, using X-ray powder diffraction and differential thermal analysis methods, show that the initial, reaction is the formation of Na₂S₂O₇. This compound melts at 402°C and the mobile liquid is an effective carrier of SO₃

Small amounts of water appear to accelerate the sulphation reaction, probably because of the formation of NaHSO₄ which also is a good solvent and a good sulphating agent for the oxides.

Résumé

Le processus de sulfatation en phase gazeuse de NiO et Co₃O₄ est normalement gêné par une couche protectrice du sulfate sur l'oxyde, mais la réaction peut étré catalysée par l'addition de petites quantités de sulfates de metaux alcalins. Des expériences faites avee du sulfate de sodium, en utilisant des méthodes de diffraction de poudre aux rayons X et d'analyse thermique différentielle, montrent que la réaction initiale est la formation de pyrosulfate de sodium. Ce composé fond a 402°C et le liquide mobile est un transporteur efficaee de trioxyde de soufre.

De faibles quantités d'eau semblent accélerer la réaction de sulfatation, probablement àcause de la formation de sulfate de sodium hydrogéné qui est aussi un bon solvant et un bon agent de sulfatation pour les oxides.     

硬质合金与工具钢的扩散焊接

探讨了过渡族金属作为过渡层金属时,其焊接工艺条件对硬质合金和合金工具钢在扩散焊接时,对结合部的强度的影响。同时还研究了过渡层金属的种类、厚度及线膨胀系数对接合强度的影响。     

The Influence of Precooling on Liquid Metal Embrittlement and Microstructure Properties of Galvanized 22MnB5 Tubes

To address the issue of liquid metal embrittlement (LME) susceptibility in galvanized 22MnB5 steel during the hot stamping process, the material's performance is affected. This study proposes a method combining precooling and tube hydroforging to produce galvanized tubular hot stamping parts. The primary workflow comprises four distinct stages: the heating phase, thermal retention phase, precooling phase, and the tube hydroforging phase. Notably, the precooling stage employs two distinct approaches: air precooling and boiling water precooling. The composition and morphology of the zinc coating and the microstructure and mechanical properties of the 22MnB5 steel are investigated using two precooling methods at different hydroforging temperatures. The results show that when the initial hydroforging temperature is below 800 °C, the precooling combined with the tube hydroforging process eliminates LME. With increasing precooling time, the oxidation reaction forms ZnO and Fe₂O₃ on the coating. By comparing the composition, morphology, and mechanical properties of the coatings at hydroforging temperatures of 800 °C and 500 °C, it is concluded that the boiling water precooling aligns more effectively with the requirements of industrial production, with the optimal forming temperature being within the range of 750–800 °C.     

国有中、小型硬质合金企业走出困境的思考

针对目前硬质合金行业及国有中、小型硬质合金企业所处的困境,提出了如何扭转局面,加强管理、摆脱困境、力争提高企业经济效益的一些相应对策和思路。     

WC-Co硬质合金在盐酸溶液中的阳极行为

为了了解WC-Co合金废料在盐酸溶液中使钴选择性溶解的阳极行为,采用了动电位扫描法研究不同的工艺条件对阳极溶解的影响,测定了阳极中钴溶解的控制步骤,并对阳极钝化的原因作了初步探讨。     

预弥散强化镍粉——硬质合金的新型粘结剂

叙述了以预弥散有纳米Ａｌ２Ｏ３的镍粉代替钴粉作粘结剂以提高ＷＣＮｉ硬质合金性能方面的初步研究；制得的ＷＣＮｉ硬质合金的物理机械性能可达到ＷＣＣｏ合金的水平     

The Role of Internal Oxides on the Liquid Metal Embrittlement Cracking During Resistance Spot Welding of the Dual Phase Steel

Metallurgical and Materials Transactions A - One of the most effective ways to improve reactive wetting of dual phase (DP) steels during galvanizing process is annealing under relatively high...     

Texture Evolution of Abnormal Grains with Post-Deposition Annealing Temperature in Nanocrystalline Cu Thin Films

We have examined the evolution of abnormal grain growth texture with increasing post-deposition annealing temperature in nanocrystalline Cu films (20 nm thick) deposited on an amorphous SiN _x (20 nm)/Si substrate. Texture is analyzed by a TEM-based orientation and phase mapping technique based on precession electron diffraction. The as-deposited film, which has an initial grain size of ~12 nm in diameter, already shows a signature of abnormal grain growth, exhibiting a bimodal grain size distribution. Texture is analyzed by calculating area fractions of major components. The overall texture of the as-deposited film is identified to be ??110??, but ??100?? grains occupy the largest fraction in the abnormally grown grain areas, followed by ??111?? grains. After annealing at 398 K, 573 K, and 773 K (125 °C, 300 °C, and 500 °C), the overall texture turns to ??112??. After annealing at 398 K (125 °C), abnormally grown grains have a major ??112?? component. The situation is similar for the film annealed at 573 K (300 °C). After annealing at 773 K (500 °C), the abnormal grain growth texture evolved into major ??111??. The ??100?? component found in the abnormal grain growth texture for the as-deposited film is clearly explained by elastic strain energy minimization and the ??111?? component for the as-deposited film and the film annealed at 773 K (500 °C) is explained by surface energy minimization. The development of the ??112?? texture obtained after annealing at 398 K and 573 K (125 °C and 300 °C) is not explained by either elastic strain energy minimization or surface energy minimization. We suggest that it is clarified by assuming that the Cu film system is perfectly elastic?Cplastic, which is associated with the Taylor factors.     

Embrittlement of copper due to segregation of oxygen to grain boundaries

The tensile and creep properties of oxygen free OF- and oxygen saturated OS-polycrystalline copper have been investigated in the temperature range 25 to 500 °C. Oxygen increases the yield strength by a factor of 2 or 3, by solid solution hardening, and for coarse-grained copper, causes a severe embrittlement, particularly under creep conditions. Both direct and indirect evidence indicate that the embrittlement is caused by the segregation of oxygen to the grain boundaries in copper, thus promoting grain boundary decohesion and intergranular fracture. Auger electron spectroscopy is used to indicate the presence of oxygen at the grain boundaries in OS-Cu. The embrittling effects of oxygen are reversible in the sense that both tensile and creep ductility are restored when oxygen is removed.     

Embankments over Soft Clay Deposits: Contribution of Basal Reinforcement and Surface Sand Layer to Stability

This paper evaluates the significance of basal reinforcement and the presence of the surface sand layer in the stability. This evaluation is carried out by means of field measurements and stability analyses of three test embankments on soft clay taken to failure. Two of the test embankments were reinforced and one was unreinforced. Stability analyses were carried out taking into account measured values of reinforcement tension forces during construction. The set of analyses have shown that the top sand layer was more important to the stability of the embankments than the basal reinforcement. The cases studied have also shown that the conventional design practice that assumes for the reinforcement a fixed tension contribution may lead to unrealistic higher factor of safety.     

金属复合氧化物纳米薄膜的防眩目原理及应用

在介绍金属复合纳米氧化物单层或多层薄膜的防眩目原理及其光干涉效应与反射率关系的基础上，指出利用多层纳米薄膜之间的干涉协同效应，在整个可见光波长范围内可达到防反射、防眩目的目的。     

The Creep-Rupture Embrittlement of Metals as Exemplified by Aluminum

Abstract

Creep-rupture tests have been conducted on a variety of alloys made from high-purity aluminum to which was added iron and silicon, both separately and in combination. The investigation was designed to provide information on the creep-rupture embrittlement of aluminum as influenced by composition and temperature, and to establish the rate at which embrittlement occurred in the tests.

Iron, by itself, was found to embrittle aluminum. The embrittling effect of silicon, by itself, was negligible. Tests on alloys containing iron alone had a tendency to show minimum ductility at intermediate times to failure. Alloys with both iron and silicon also showed minimum ductility at about the same time to failure, but this minimum was at lower ductility values, and remained constant, for each test, at longer times to failure. Increments of iron above about 0.1 per cent do not necessarily confer increasing embrittlement.

Annealing at higher temperatures improves the ductility of these alloys, as shown by tests at lower temperatures.

The rate of embrittlement, at testing temperatures where embrittlement is pronounced, is very slow in the early stages of a test but accelerates rapidly near the end.

The results of the investigation confirm a previously stated postulate that impairment of cohesion across grain boundaries, by impurities accumulated in the course of creep-rupture tests of metals, is a necessary and sufficient condition for the development of intercrystalline embrittlement.