A.A.Al-Aql
,
M.S.Al-Salhi
,
M.I.Ansari
材料科学技术（英文）
Precipitation study was carried out in Ni-35 at. pct Cr alloy by measuring electrical resistivity at different ageing temperatures and long ageing times. During ageing, it was observed that electrical resistivity initially rose with ageing time and then fell after very long ageing at a constant temperature. The initial increase in resistivity during ageing may be attributed to the formation of GP zones/Cr-rich precipitates at early stages by nucleation process and decrease in resistivity, and after attaining a maximum, is due to the growth of precipitate particles and subsequently by coarsening of these precipitates. The results of electrical resistivity measurements during ageing were confirmed by X-ray diffraction analysis indicating the formation of a Cr-rich phase and a Cr3Ni2 phase in the Ni matrix.
关键词:
Precipitation
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null
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null
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null
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null
鲜晓斌
,
刘柯钊
,
吕学超
,
张永彬
稀有金属材料与工程
用循环Ar+轰击-磁控溅射离子镀(MSIP)法在U表面上镀Al,Ti/Al,并采用俄歇电子能谱仪(AES)、扫描电镜(SEM)、电化学实验和平面磨耗实验,研究了其表面、剖面形貌和耐磨耐蚀性能,以及Al/U和Ti/Al镀层界面.结果表明:U上循环Ar+轰击-磁控溅射离子镀Al,Ti/Al界面存在较宽的原子共混区,且Ti/Al镀层的耐磨耐蚀性能明显优于单一磁控溅射离子镀Al层.
关键词:
Ti/Al镀层
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界面
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耐磨性
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耐蚀性
Y.Ma
,
Y.Hao
,
S.Z.Kou
,
X.N.Lu
金属学报(英文版)
Based on the experiment and the thermodynamics analysis for CuO/Al system, it is founded that the compounding reaction of CuO/Al under low temperature is available. The general equation of adiabatic temperature of the system is set up, and the influence of resultant concentration and temperature on adiabatic temperature is theoretically analyzed. The values of heat effect of CuO/Al system under different temperature are also caculated.
关键词:
composite in situ
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null
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null
Hong TAO
,
Chengji DENG
,
Lianmeng ZHANG
,
Runzhang YUAN
材料科学技术（英文）
Al/Al2O3 composites of different ratios were hot-press sintered at 575 similar to 640℃ under a pressure of 30 MPa for 2 h in a vacuum furnace. It was found that the relative density of the Al/Al2O3 composites could be increased evidently with the rise of sinter temperature. No reaction occurred between Al and Al2O3 at the sinter temperatures. Under 640℃-30 MPa-2 h experimental condition, Al/Al2O3 system FGM was successfully fabricated, and its density range changed quasi-continuously from 2.887x10(3) kg/m(3) to 3.1909x10(3) kg/m3 within the middle 1.0 mm thickness range.
关键词:
YANG Wenying LU Fanxiu ZHANG Shouhua University of Science and Technology Beijing
,
Beijing
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China Department of Materials Science and Engineering
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University of Science and Technology Beijing
,
Beijing
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100083
,
China
金属学报(英文版)
The “order-disorder” model was adopted to calculate the lattice vacancies related to the com- position change in Ni_3Al alloys.A great deal of vacancies,i.e.,the non-stoichiometric vacan- cies,may exist in the Ni_3Al alloys containing Al over stoichiometry,i.e.25 at.-%.This was confirmed by the positron annihilation technique.Therefore,the influence of Al content on the enhancing behaviour of B towards the ductility of Ni_3Al alloys can be understood by the interaction of non-stoiehiometric vacancies and B atoms.
关键词:
Intermetallic compounds
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null
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null
Lin GENG Congkai YAO Dept.of Metals and Technology
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Harbin Institute of Technology (HIT)
,
Harbin
,
150006
,
China
材料科学技术（英文）
The microstructure of SiC whisker reinforced aluminium alloy (SiC_w/Al) composite is reviewed,and the SiC-Al interface in SiC_w/Al composite is especially discussed,The main contents are morphology of the aluminium matrix in SiC_w/Al composite;microstructures and defects of SiC whiskers in SiC_w/Al composite and bonding mechanisms of the SiC-Al interface in SiC_w/Al com- posite.
关键词:
silicon carbide
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null
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null
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null
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null
Scripta Materialia
Three-dimensional atom probe has been applied to investigate the solubility of Si in Al(3)SC in an Al-0.16Sc-0.05Si alloy. It was found that L1(2)-structured Si-containing Al(3)Sc precipitates formed after the alloy was aged at 300 degrees C. Results of first-principles calculation indicated that Si atoms tend to substitute Al sites in Al(3)Sc, and thus the precipitates can be represented as (Al,Si)(3)Sc. The (Al,Si)(3)SC was found to have a dramatic precipitation-strengthening effect in the cast alloy. (C) 2009 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
关键词:
Aluminium alloys;Ageing;3DAP;Precipitation;Hardness test;aluminum-alloys;coherency loss;evolution;zr
材料科学技术（英文）
The SiCP/(Al-Cu) alloy and pure Al matrix composites have been prepared by the centrifugal casting with electromagnetic stirring. There are two particle-depleted zones formed in the samples without electromagnetic stirring. Electromagnetic stirring may result in a homogeneous distribution of fine SiC particles in the Al-Cu alloy, whereas it has little effect on the segregation in pure Al matrix. The results also show that the particle segregation is influenced by particle size and the coarse particles are more readily segregated than the fine ones.
关键词:
centrifugal casting;particle distribution;electromagnetic stirring;solidification
