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Diffusion mechanism of dezincification in double phase brass exposed to seawater

中国有色金属学会会刊：英文版 1999年第3期9卷 572-577页

作者： Liu Zengcai(刘增才) Lin Leyun(林乐耘) Liu Shaofeng(刘少峰) Zhao Yuehong(赵月红) gen res inst nonferrous met Beijing 100088 Peoples R China

Zinc diffusion kinetics of double phase brass as they were corroded in seawater was investigated by means of metallography microscope and mathematics regression analysis. The results showed that, the dezincification corrosion of β phase continuous HMn58 2 brass is characterized by β phase volume diffusion, while that of α phase continuous HSn62 1 brass is controlled by α phase grain boundary diffusion. Apparent diffusion coefficients of zinc in both types alloys were calculated out by founding diffusion equation and boundary conditions. It was found that the value of theoretical calculation is close to that of experimentally measured, and it confirmed that Sn element inhibits dezincification of brass. The relativity between the dezincification depth and corrosion rate of different double phase brasses immersed in seawater was revealed. : Zinc diffusion kinetics of double phase brass as they were corroded in seawater was investigated by means of metallography microscope and mathematics regression analysis. The results showed that, the dezincification corrosion of β phase continuous HMn58 2 brass is characterized by β phase volume diffusion, while that of α phase continuous HSn62 1 brass is controlled by α phase grain boundary diffusion. Apparent diffusion coefficients of zinc in both types alloys were calculated out by founding diffusion equation and boundary conditions. It was found that the value of theoretical calculation is close to that of experimentally measured, and it confirmed that Sn element inhibits dezincification of brass. The relativity between the dezincification depth and corrosion rate of different double phase brasses immersed in seawater was revealed.

关键词： seawater corrosion brass dezincification boundary diffusion

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Heat Treatment, Microstructure and Mechanical Properties of the Squeezing Cast Al-7.8Zn-2.0Mg-1.6Cu-0.15Zr-0.18Sc Alloy

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稀有金属材料与工程 2011年第S3期40卷 82-85页

作者： Tu Qiang, Yang Fubao, Xu Jun, Zhang Zhifeng, Li Daquan nonferrous metals Processing Division , general research institute for Non-ferrous metals, Beijing 100088, China gen res inst nonferrous met Nonferrous Met Proc Div Beijing 100088 Peoples R China

The microstructure of squeezing cast Al-7.8Zn-2.0Mg-1.6Cu-0.15Zr-0.18Sc alloy and those after industrial homogenization treatment and multi-stage solution treatments, were studied by differential scanning calorimetry (DSC), optical microscopy (OM), transmission electron microscope (TEM), scanning electron microscopy with energy dispersive X-ray spectroscopy (TEM-EDX). The results shows that, by complex adding the micro-alloying elements Mn, Sc, Zr, etc ,the microstructure of squeezing casting ingot are fine, uniform, equiaxed, and with the average sizes of 40 μm. The melting point of the non-equilibrium eutectic is 468 ℃ for the casting ingot. After industrial homogenization treatment at 450 ℃ for 24 h, the tensile strength of as-cast alloy is 340-350 MPa and the elongation is 3.5%-4.5%. The multi-stage solution treatment at 465 ℃, 48 h +475 ℃, 8 h +485 ℃, 2 h results in the disappearance of the non-equilibrium eutectics at grain boundary, though some phases containing Fe and Cu can not dissolve completely. After 120 ℃, 24 h aging treatment, the tensile strength is nearly 600 MPa, and the elongation improve to more than 10%.

关键词： squeezing casting homogenization treatment multi-stage solution mechanical properties

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Structural evolution of non dendritic AlSi7Mg alloy during reheating

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中国有色金属学会会刊：英文版 1999年第3期9卷 553-556页

作者： Zhang Kui(张奎) Zhang Yongzhong(张永忠) Liu Guojun(刘国均) Xu Jun(徐骏) Zhang Jingxin(张景新) Fan Jianzhong(樊建中) Shi Likai(石力开) gen res inst nonferrous met Beijing 100088 Peoples R China

The structural evolution of non dendritic AlSi7Mg alloy during reheating in resistance furnace was studied. The alloy ingots were produced by electromagnetic stirring during solidification. It was found that, the Si phase in eutectic dissolves in a way of diffusion toward α phase, its appearance changes from flake to dot like, and tends to be fine and spheroidal with increasing reheating temperature. The thinner the flake, the lower the temperature for the occurrence of this process, and the higher the transforming speed. The eutectic melts partially when Si phase dissolves to some extent, and the morphology and size of primary α phase begin to change. The dendrite and rosette α phases tends to sphericize. The size of the former becomes larger, while the size of the latter reduces to be 1/2～1/4 of the original size. The spheroidal primary α phase has a tendency of grain growth.

关键词： aluminum alloys reheating non dentritic structure transformationDocument code: A

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Synthesis and Properties of Layered Oxides LiCo_(1-x)Ni_xO_2

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Journal of Materials Science & Technology 1997年第5期13卷 405-408页

作者： Lin, Q Chen, N Ye, W Liu, RM Luo, JS gen res inst nonferrous met BEIJING 100088PEOPLES R CHINA

The mechanism of LiCo1－xNixO2(x=0, 0.5, 1) synthesis from carbonates or hydrates was studied by thermogravimetric analysis and X-ray diffraction to identify the medium and final products. The synthesis process from carbonates can be divided into two steps. Below 300℃cobalt carbonate and/or nickel carbonate decompose forming oxides. Over 300℃ Li2CO3 decomposes and reacts with Co and/or Ni oxides gradually, as a result Co++ and/or Ni++ areoxidized to Co+++ and/or Ni+++, finally LiCo1-xNixO2 forms. The proportion of cobalt tonickel in the starting mixture and atmosphere during synthesis affects the structure of ***1-xNixO2(x≤0.5) can be synthesized in air or oxygen and characterized by solid solutionof LiCoO2 and LiNiO2. LiNiO2 can be obtained only from hydrates and in oxygen *** and LiCo0.5Ni0.5O2 have higher first charge capacity than that of LiCoO2. Their discharge capacity reaches a level with that of LiCoO2 and has reasonable reversibility.

关键词： Lithium batteries

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Interface Characterization of the SiCp/Al Composites Made by Powder metallurgy

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Journal of Materials Science & Technology 1999年第2期15卷 147-150页

作者： Fan, JZ Zhang, K Shi, LK Zhang, SM gen res inst nonferrous met Beijing 100088 Peoples R China

The interface of the SiCp/Al composites produced by powder metallurgy processing involving hot-pressing above the matrix solidus temperature has been investigated by means of TEM. Several kinds of interfaces between the reinforcements and the matrix in the composite, including the clean interfaces, the faceted interfaces and the slight reaction interfaces, are presented. And most of interfaces belong to the slight reaction interfaces which are composed of the Al with different orientation from the Al matrix near the interface zone and particle-like substances produced by MgAl2O4 spinels and impurities.

关键词： metallic matrix composites

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Preparation of tube blanks by atomization deposition process

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中国有色金属学会会刊：英文版 1999年第3期9卷 472-476页

作者： Xiong Baiqing(熊柏青) Zhang Yongan(张永安) Lin Yaojun(林耀军) Zhang Shaoming(张少明) Shi Likai(石力开) gen res inst nonferrous met Beijing 100088 Peoples R China

By using the method of mathematical calculation combined with experiment, the technological conditions of atomization deposition process for making tube blanks with even thickness were studied. The results show that in the case of the substrate rotating and translating simultaneously, when the ratio of the rotation frequency to the translational velocity is very large, and the other deposition conditions are suitable, tube blanks with even thickness and high density can be produced, and the actual deposition efficiency will be highest.

关键词： atomization deposition process tube blanks rotation frequency translational velocity Document code:A

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Effects of Solution Treatment on the Microstructure and Mechanical Properties of Al-16.9Si-4.5Cu-0.15Mg Alloy

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稀有金属材料与工程 2011年第S3期40卷 73-77页

作者： Zhang Xun, Zhang Zhifeng, Xu Jun general research institute for Non-ferrous metals (GRINM), Beijing 100088, China gen res inst nonferrous met GRINM Nonferrous Met Proc Div Beijing 100088 Peoples R China

In this paper, the microstructure and mechanical properties of Al-Si-Cu-Mg casting alloy under different solution conditions were investigated by optical metallographic and mechanical property test. The results show that the cast alloys were composed of α-Al, primary Si, eutectic Si, Al2Cu and Al7Cu2Fe phases. Three changes took place during solution treatment: Firstly, with the increase of solution temperature and the solution holding time extension, more and more Al2Cu phase was dissolved into the matrix; Secondly, with the increase of solution temperature and the solution holding time extension, morphology of eutectic Si, Al7Cu2Fe and other insoluble phases changed into more round; Thirdly, at the fixed solution temperature, if the solution time extended too long, it would cause grains, eutectic Si and other insoluble phases aggregated and coarsened. About mechanical properties, when the solution time was fixed, the hardness, tensile strength and the yield strength of the Al-Si-Cu-Mg alloy treated by T6 enhanced while the solution temperature increasing, and when the solution temperature was fixed, the ultimate tensile strength and the elongation of the Al-Si-Cu-Mg alloy treated by T6 increased at first and then decreased while the solution time increasing, but the hardness of the alloys affected less by the solution time.

关键词： Al-Si-Cu-Mg alloy solution treatment microstructure mechanical properties

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Flow Behavior and Microstructures of Inconel 625 Superalloy at the Elevated Temperature

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稀有金属材料与工程 2011年第S3期40卷 95-98页

作者： Li Defu, Guo Shengli, Wu Zhigang, Zou Honghui, Pen Haijian general research institute for nonferrous metals, Beijing 100088, China gen res inst nonferrous met Beijing 100088 Peoples R China

The deformation behavior of Inconel 625 superalloy was investigated by means of hot compression tests. The flow stress curves were obtained in the temperature and strain rate ranges of 950-1200 ℃ and 0.01-10 s-1, respectively. Optical microscopy was used to evaluate the microstructural evolution of the alloy under different conditions examined. The results show that the flow stress decreases with decreasing strain rate and increasing temperature, and the activation energy is about 654.502 kJ/mol. Microstructure observations show that with increasing temperature, the sizes and volume fraction of dynamic recrystallization (DRX) grains increase. The strain has no remarkably effect on the sizes of DRX grains, but with increasing strain the volume fraction of DRX grains increases. During hot compression of Inconel 625 superalloy at elevated temperature, the occurrence of DRX was the main softening mechanism. The DRX mechanism of Inconel 625 superalloy can be mainly attributed to the discontinuous dynamic recrystallization (DDRX).

关键词： inconel 625 superalloy hot deformation flow stress dynamic recrystallization

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Effect of Alloying Elements on the Quality of Hard Anodic Oxidation Film in Aluminum Alloy 6061

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稀有金属材料与工程 2011年第S3期40卷 59-62页

作者： Yang Yin, Shen Jian, Yan Xiaodong, Xu Xiaojing, Li Junpeng, Jiang Tao Beijing general research institute for Non-ferrous metals, Beijing 100088, China Beijing gen res inst nonferrous met Beijing 100088 Peoples R China

the effect of different Mg/Si and Mn content on uniformity and consistence of anodic films of 6061 aluminum alloy was investigated by using hardness test,coating thickness test, optical microscopy (OM),scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The results show that when Mg/Si is in the vicinity of 1.73 and Mn content is 0.14%, the uniformity of the anodic film is the best while the consistence of the anodic film is the best when Mg/Si is 1.88 and Mn content is 0.14%. Superfluous silicon and magnesium have a bad function on the uniformity of anodic films of 6061 aluminum alloy because of secondary phases but magnesium in the base material can be beneficial for the consistence of the anodic film due to formation of a protective, impermeable layer of MgO below the anodic film while plentiful excess silicon result in single Si and w(Cu4Mg5Si4Alx) to gather in the grain boundary, which makes rarefactions and discontinuity present. The uniformity and consistence of anodic films are improved by Mn content rising, which is caused by the decrease of needle-like Fe-rich and Mg2Si phases and the increase of bone-like Fe-rich phases.

关键词： aluminum alloy 6061 uniformity densification anodic oxidation film

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Microstructure and tensile properties of low cost titanium alloys at different cooling rate

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Rare metals 2012年第6期31卷 531-536页

作者： Wang Guo Hui Songxiao Ye Wenjun Mi Xujun Wang Yongling Zhang Wenjing gen res inst nonferrous met State Key Lab Fabricat & Proc Nonferrous Met Beijing 100088 Peoples R China

Titanium and titanium alloys have several advantages, but the cost of titanium alloys is very expensive compared with the traditional metal materials. This article introduces two new low-cost titanium alloys Ti-2.1Cr-1.3Fe (TCF alloy) and Ti-3Al-2.1Cr-1.3Fe (TACF alloy). In this study, we used Cr-Fe master alloy as one of the raw materials to develop the two new alloys. We introduce the microstructure and tensile properties of the two new alloys from β solution treated with different cooling methods. Optical microscopy (OM), X-ray diffractometry (XRD), and transmission electron microscopy (TEM) were employed to analyze the phase constitution, and scanning electron microscopy (SEM) was used to observe the fracture surfaces. The results indicate that the microstructures consist of β grain boundary and α′ martensite after water quenching (WQ), β matrix and α phase after air cooling (AC) and furnace cooling (FC), respectively. Also, the microstructure is the typical basketweave structures after FC. Of course, athermal ω is also observed by TEM after WQ. The strength increases with decreasing cooling rates and the plasticity is reversed. Because of the athermal ω, the strength and ductility are highest and lowest when the cooling method is WQ. The strength of TACF alloy is higher than the TCF alloy, but the plasticity is lower. The fracture surfaces are almost entirely covered with dimples under the cooling methods of AC and FC. Also, we observe an intergranular fracture area that is generated by athermal ω, although some dimples are observed after WQ.

关键词： titanium alloys microstructure martensite tensile properties fracture morphology

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