J.H.Thndermann(Inco Alloys International
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Inc.
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Huntington
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WV 25705
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USA Manuscript received 26 August 1996)
金属学报(英文版)
Low thermal expansion superalloys have been used for a number of years in a variety of applications, including gas turbine engines. The low thermal expansion characteristics of the most widely used class of materials are derived from the ferromagnetic characteristics of Ni, Fe, and Co-based austenitic matrices containing little or no Cr.Alloy developments have been aimed at improving the oxidation resistance and stress accelerated grain boundary oxygen (SAGBO) attack.INCONEL alloy 783 is an oxidation resistant, low coefficient of thermal expansion superalloy developed for gas turbine applications. Alloy 783 represents a culmination in the development, of an alloy system with very high alumtnum content that, in addition to forming γ′,causes βaluminide phase precipitation in the austenitic matrix.This type of structure can be processed to resist both SAGBO and general oxidation,while providing low thermal expansion and useful mechanical properties up to 700℃.Key aspects of the alloy's development are presented.
关键词:
:coefficient of thermal expansion
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null
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Y.L. Chen(Department of Materials Science and Engineering
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Zhejiang University
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Hangzhou 310027
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China)
金属学报(英文版)
Internal friction measurements on binary and ternary α-phase alloys of Pd with hydrogen and boron have been performed with a torsion pendulum and by observing the cttenuation of ultrasonic pulses. A pronounced damping maximum of binary Pd-B alloys at 220K and measuring frequencies of about 4Hz could not be established at a frequency of 15MH. Ternary Pd-B-H alloys show an additional damping maximum besides the hydrogen Zener effect, which is interpreted in terms of a changed jump frequency of hydrogen in the neighborhood of boron atoms.
关键词:
Pd-B-H alioy
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null
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null
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孙建春
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盛光敏
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陈登明
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周安若
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朱光俊
功能材料
1J50软磁合金的性能主要是通过H_2热处理获得的,在1130℃和H2气氛保护下对冷轧态1J50软磁合金进行了热处理.运用MATS-2010SA软磁测试仪对处理前后1J50软磁合金的磁性能进行了检测,运用金相显微镜、XRD等手段对处理前后1J50软磁合金的组织结构进行了分析.结果表明,通过H_2热处理,1J50软磁合金的矫顽力显著降低,起始磁导率和最大磁导率提高;组织结构发生明显变化,冷轧态1J50软磁合金组织为孪晶奥氏体,平均晶粒尺寸为200μm,处理过后,晶粒显著长大,平均晶粒尺寸为100μm;由于在600℃时采取了快冷,处理后1J50软磁合金中未出现大量FeNi相和FeNi_3相.
关键词:
H2热处理
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1J50
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组织结构
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性能
李智伟
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王宏伟
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魏尊杰
稀有金属材料与工程
在1100-1230℃的温度下真空烧结表面涂覆一层由聚乙烯醇粘结剂、合金粉末和分散剂构成的浆料的聚苯乙烯球制得高孔隙率的INCO-617合金空心球颗粒,对不同烧结工艺下制备的空心球颗粒的显微组织和力学性能进行了研究.结果表明,INCO-617合金空心球颗粒的密度随烧结温度的升高和烧结时间的延长而增加,其密度值在1.504～2.113 g/cm3之间.烧结温度的升高和烧结时间的延长可以明显减少球壁的残余孔隙,这是空心球颗粒显微硬度和压缩性能提高的主要原因,并且,随着球壁内残余孔隙的降低,空心球颗粒压缩时脆性破坏的倾向被抑制.
关键词:
空心球颗粒
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INCO-617合金
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烧结
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力学性能
F.Gesmundo F.Viani Instituto di Chimica
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Facolta di Ingegneria
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Universita di Genova
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Genova
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16129
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ItalyY.NIU Corrosion Science Lab.
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Institute of Corrosion and Protection of Metals
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Academia Sinica
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Shenyang
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110015
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China
材料科学技术（英文）
The corrosion of alloys based on Fe,Co and Ni containing 15 and 30 wt-% Nb was studied at 700℃ in H_2-H_2S mixtures providing 10~(-8) atm S_2.The Fe and Co-based alloys formed duplex scales with an outer layer of pure base-metal sulphide and an inner layer containing both metals.The Nb addi- tions were not able to produce exclusive Nb sulphidation but yielded a significant decrease of the corrosion rates for both types of alloys with respect to the pure metals even though they were still much higher than that of pure Nb.The Ni-base alloys corroded rapidly forming a single complex scale layer,mainly due to the appearance of a liquid Ni-S solution.
关键词:
niobium
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Corrosion Science
The sulfidation behavior of two Fe-Ce alloys containing approximately 15 and 30 wt% cerium has been studied at 600-800 degrees C in H-2-H2S mixtures providing a sulfur pressure of 10(-8) atm. The alloys corrode more slowly than pure iron, but more rapidly than pure cerium. The sulfidation rates generally decrease with time and tend to become parabolic after an initial stage intermediate between linear and parabolic, except for Fe-15Ce which corrodes linearly after an initial quasi-parabolic behavior. Both alloys produce complex scales, containing an outermost layer of practically pure iron sulfide and an inner complex layer where the sulfides of both alloy components are simultaneously present. Finally, a thin region of internal sulfidation of cerium is also generally present in contact with the alloy which is not depleted in cerium. Cerium is not able to diffuse out of the alloy consumption region, where it forms a cerium sulfide mixed with iron sulfide. The iron sulfide forms a continuous network which allows the growth of the external FeS layer, even though at rates reduced with respect to pure iron. Thus, a cerium/content up to 30 wt% is not sufficient to prevent the sulfidation of pure iron. These results as well as the details of the microstructure of the scales grown on the two alloys are interpreted by taking into account the limited solubility of cerium in the base metal and the presence of intermetallic compounds in the alloys. (C) 1997 Elsevier Science Ltd.
关键词:
iron;cerium;sulfidation;high temperatures;2-phase binary-alloys;high-temperature sulfidation;possible scaling;modes;low oxidant pressures;nb alloys;h2-h2s mixtures;mo alloys;oxidation;600-degrees-c-800-degrees-c;corrosion
Corrosion Science
The sulphidation of two copper-silver alloys containing 5 and 10 wt.% silver (Cu-5Ag and Cu-10Ag, respectively) was investigated over the temperature range 550-750 degrees C in H-2/H2S mixtures under sulphur pressures below the dissociation of Ag2S. External scales, composed mainly of cuprous sulphide, often containing some (Cu,Ag)(2-x)S islands, formed on both alloys. The corrosion kinetics were significantly affected by the detachment of the outer scales at temperature, as a consequence of the significant volume increase due to sulphidation. After scale detachment, sulphidation proceeded through a dissociative transport of sulphur in voids between the outer sulphide layer and the alloy substrate, yielding an abrupt decrease of the corrosion rate in all cases and modifying the composition of the reaction products in the case of Cu-10Ag. An increase of the volume fraction of the silver-rich solid solution in the subscale region with respect to the original alloy was observed in all cases. The silver islands coalesced to a continuous subscale layer only in the sulphidation of Cu-5Ag at 650 and 750 degrees whereas, in all the other cases, they remained as particles in a Cu2S matrix. The peculiar corrosion behaviour of these alloys is attributed to the low solubility of silver in copper. (C) 1999 Elsevier Science Ltd. All rights reserved.
关键词:
sulphidation;copper;silver;two-phase alloys;state corrosion kinetics;2-phase binary-alloys;most-stable oxide;internal oxidation
Oxidation of Metals
The sulfidation behavior of three two-phase Fe-Cu alloys containing 25, 50, and 75 wt.% copper has been investigated in H-2-H2S mixtures at 500-700 degrees C under gas-phase sulfur pressures, which is significantly above those for the dissociation of both FeS and Cu2S. In all cases, the three alloys sulfidized more slowly than both pure metals under the same conditions. At all temperatures, Fe-25Cu showed the slowest growth rates, whereas Fe-50Cu sulfidized more rapidly than the other two alloys. However, the kinetics curves for the three alloys tended to over lap, particularly at the higher temperatures. The scales were complex and contained an outer layer composed of a mixture of two different Cu-Fe double sulfides, Cu5FeS4 and CuFeS2, plus an inner zone containing a mixture of metallic iron with the double sulfide Cu5FeS4 formed by complete sulfidation of the copper-rich phase anti partial sulfidation of the iron-rick phase. This region also contained large voids, possibly because of outward diffusion of metal cations, whereas the iron-rich islands were mainly unattacked. The depth of intrenal attack increased with increasing temperature and/or iron content. Finally, particles of almost pure copper metal, probably formed during cooling from the reaction temperature,,were present at the scale-subscale interface, as inclusions in the scale and as whiskers producing out of the external scale surface.
关键词:
sulfidation;iron-copper;two-phase alloys;2-phase binary-alloys;ni-nb alloys;high-temperature oxidation;most-reactive component;possible scaling modes;low oxidant pressures;low-oxygen pressures;1 atm o-2;h2-h2s mixtures;air oxidation
Huijie LIU
材料科学技术（英文）
The friction stir weldabilities of the strain-hardened AA1050-H24 and precipitate-hardened AA6061-T6 aluminum alloys were examined to reveal the effects of material properties on the friction stir welding behavior. The experimental results are obtlained. (1) For AA1050-H24, the weld can possess smoother surface ripples; there is no elliptical weld nugget in the weld; there is no discernible interface between the stir zone and the thermomechanically affected zone; and the internal defect of the weld looks like a long crack and is located in the lower part of the weld. (2) For AA6061-T6, the weld usually possesses slightly rougher surface ripples; an elliptical weld nugget clearly exists in the weld; there are discernible interfaces among the weld nugget, thermomechanically affected zone and heat affected zone; and the internal defect of the weld is similar to that of the AA1050-H24 weld. (3) The effective range of welding parameters for AA1050-H24 is narrow, while the one for AA6061-T6 is very wide. (4) The maximum tensile strength efficiency of the AA1050-H24 joints is similar to that of the AA6061-T6 joints, i.e. 79% and 77%, respectively.
关键词:
Friction stir weldability
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Oxidation of Metals
The sulfidation of three Cu-Cr alloys with nominal Cr contents of 25, 50, and 75 wt.% and of the two pure metals has been studied at 400-600 degrees C in H-2-H2S mixtures under sulfur pressures of 10(-12) atm at 400 and 500 degrees C and 10(-10) arm at 500 and 600 degrees C, slightly above the Cu-Cu2S equilibrium All the alloys were two-phase, containing a mixture of the solid solution of chromium in copper with nearly pure chromium. The corrosion rates of the three materials under the same conditions were similar and intermediate between those of the two pule metals and increased with temperature and sulfur pressure. The scales had a complex composition, often containing an external Cu2S layer, which became discontinuous or even disappeared, in some cases, followed by an intermediate layer of the double Cu-Cr sulfide CuCrS2 and an innermost complex layer, which generally consisted of a mixture of the double Cu-Cr sulfide CuCr2S4 with the chromium sulfide CrS and also commonly contained unsulfidized chromium metal particles. No chromium depletion was developed in the alloys beneath the corrosion-affected region. Moreover; no internal sulfidation of chromium was observed in the alloy richest in copper and no exclusive external sulfidation of chromium in those richest in chromium, in spite of the large difference in the thermodynamic stabilities of the sulfides of the two pure metals. These peculiar scale features are interpreted by taking into account the special two-phase nature of these alloys.
关键词:
sulfidation;copper;chromium;two-phase alloys;2-phase binary-alloys;co-nb alloys;high-temperature oxidation;low-oxygen pressures;most-reactive component;possible scaling modes;low oxidant pressures;1 atm o-2;h2-h2s mixtures;600-800-degrees-c
