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Oxidation behavior of the Fe-36Al-0.09C-0.09B-0.04Zr alloy at 1250℃

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International Journal of Minerals,Metallurgy and Materials 2010年第4期17卷 441-447页

作者： Jun-you Liu Feng Li Jie Liu Yi Zhang Jin-cheng Jiang Dun-xu Zou School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China Beijing BKDR Metallurgy Engineering ＆ Technology Co. Ltd. Beijing 100083 China China Iron ＆ Steel Research Institute Group Beijing 100081 China

To explore and study the Fe-A1 system alloy presenting exceptional oxidation resistance at high temperature, the Fe-36Al-0.09C-0.09B-0.04Zr alloy was designed and developed. The microstructure and hardness of the backing at 1250℃were analyzed and measured. Thermodynamics and kinetics of the oxidation behavior were also analyzed by X-ray diffraction, scanning electron micros- copy, and energy-dispersive X-ray spectroscopy techniques. The results show that the microstructttre of the Fe-36Al-0.09C-0.09B-0.04Zr alloy is FeAl phase at ambient temperature and is stable at 1250℃. It displays the excellent property of oxidation resistance because the oxide film has only the Al2O3 layer, and its oxidation kinetics curve obeys the parabolic law at 1250℃. The oxidation mechanism at 1250℃ is presumed that in the early oxidation period, the alloy oxidizes to form a large number of Al2O3 and a little Fe2O3, then, the enrichment of Al caused by Fe oxidization combines with O to form Al2O3.

关键词： Fe-alloy oxidation behavior oxide film oxidation thermodynamics oxidation kinetics

Influence of Yttrium Implantation on Oxidation Behavior of Co-40Cr Alloy at 900℃

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Journal of Rare Earths 1999年第1期17卷 35-38页

作者：靳惠明李铁藩李美栓沈嘉年辛丽黄健宇 Inst of Corrosion and Protection of Metals Chinese Acad of Sciences Shenyang China

The oxidation behavior of Co 40Cr alloy with and without yttrium implantation was studied at 900 ℃ in the air. Scanning electron microscopy(SEM), secondary ion massive spectroscopy(SIMS), transmission electron microscopy(TEM) and high resolution electron microscopy(HREM) were used to study the forming mechanism of oxide film on the alloy. It is found that the binding energy of Cr on the alloy surface is decreased by yttrium implantation, thus the formation of protective Cr 2O 3 film on the substrate is accelerated. In the mean time, the binding energy of Cr inside the oxide scale is increased by yttrium implantation, and this would reduce the Cr 3+ cation diffusion through the film. Yttrium implantation decreases the grain size and the growing speed of oxide film. SIMS and TEM/HREM results show that some yttrium exists as small YCrO 3 particles at Cr 2O 3 grain boundary near the oxide/gas interface, and a few small Y 2O 3 particles exist near the substrate/oxide interface. Besides, yttrium may also segregate to Cr 2O 3 grain boundary as Y 3+ , reduce Cr 3+ cation diffusion and change the mechanical properties of the oxide film. The ability of anti oxidation of Co 40Cr alloy is greatly improved by yttrium implantation.

关键词： Rare earths oxide film Binding energy Ion implantation

Influence of element Cu on hydrogen content in superheated aluminum melt

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中国有色金属学会会刊：英文版 2001年第3期11卷 358-360页

作者：李喜珍边秀房李秀军王丽山东大学教育部材料液态结构及其遗传性重点实验室山东济南 250061 山东大学化学系山东济南 250100

The hydrogen content in molten Al Cu alloy increases remarkably when the temperature of the melt rises to about 780 ℃. The effects of alloying element are theoretically analyzed in terms of Wagner interaction parameter. Furthermore, analyses indicate that the alloy element Cu plays an important role in the hydrogen content in superheated Al Cu alloy melt below about 780 ℃. The conclusion is drawn that the degree of gassing in molten Al Cu alloy is bound up with the properties of oxide film of Al alloy melts. The results make it clear that the hydrogen content in the molten aluminum reduces with increasing element Cu dissolved in aluminum melts at the same temperature. [

关键词： element Cu hydrogen interaction parameter oxide film

Epitaxial growth and thermostabiUty of cubic and hexagonal SrMnO3 films on SrTiO3（111）

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Frontiers of physics 2015年第3期10卷 83-88页

作者： Rui-Nan Song Min-Hui Hu Xiang-Rong Chen Jian-Dong Guo Institute of Atomic and Molecular Physics College of Physical Science and Technology Sichuan University Chengdu 610065 China Institute of Physics Chinese Academy of Sciences Beijing 100190 China Key Laboratory of High Energy Density Physics and Technology of Ministry of Education Sichuan University Chengdu 610064 China Collaborative Innovation Center of Quantum Matter Beijing 100871 China

The growth of SrMnO3 films on SrTiO3（111） substrates by pulsed laser deposition was studied and found to produce cubic and hexagonal （4H） structures in the SrMnO3 films. By adjusting the substrate temperature and oxygen pressure, the stability of the two phases was fine-tuned, resulting in the growth of cubic-SrMnO3（lll） or 4H-SrMn03（0001） film, with the 4H phase being the more stable at room temperature and ambient pressure in the bulk form. The growth temperature of the cubic phase was also further lowered relative to the bulk thermodynamics by strain at the heterointerface, and once obtained, it was stable at temperatures of up to 800 ℃.

关键词： oxide film pulsed laser deposition heteroepitaxy SrMn03

Influence of Elemental Iron on Hydrogen Content in Superheated Aluminum-iron Melts

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Journal of Wuhan University of Technology(Materials Science) 2004年第2期19卷 57-61页

作者：胡丽娜 ANANDA Mahto DUAN You-fengShandong University

The hydrogen content in liquid binary aluminum alloys with 1,3,5 and 8 wt% iron has been determined in the temperature range from 973K to *** hydrogen content in molten Al-Fe alloys increases remarkably when the temperature of the melt rises to about *** work indicates that the alloying element iron plays an important role in hydrogen content in superheated Al-Fe alloy melts below about *** results make it clear that the hydrogen content in the melt aluminum reduces with the increasing element levels.A conclusion is drawn that the degree of gassing in molten Al-Fe alloys is bound up with the properties of oxide film of aluminum alloy *** element iron has no effect on the compact structure of oxide film in aluminum *** effects of alloying element are theoretically analyzed in terms of Wagner interaction *** to the values of the first order interaction parameter,it is concluded that the interaction between iron atom and aluminum is much stronger than that between hydrogen atom and aluminum,and the addition of the alloying element decreases the affinity of liquid aluminum for hydrogen.

关键词： aluminum-iron alloy hydrogen interaction parameter oxide film

Research of stress corrosion cracking of T225NG titanium alloy in loop water of high temperature and high pressure

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China Welding 2006年第1期15卷 26-29页

作者：徐济进严铿陈立功蒋成禹 School of Materials Science and Engineering Shanghai Jiaotong UniversityShanghai200030 School of Materials Science and Engineering East China Shipbuilding Institute Zhenjiang212003

Double cantilever beam （DCB） specimens were used to research the stress corrosion cracking of T225NG titanium alloy in loop water of high temperature and high pressure. DCB specimens were forced pre-stress, put into high pressure ataoclave , and the stress corrosion and crack expansion of specimens were observed and measured in 500 h, 1 000 h and 2000 h respectively. The results show that small expansion occurred along the direction of pre-cracking. According to calculation, the speed of cracking expansion is lower than 10 -9 m/s in 500 h and the value of K ISCC /KI is higher than 0. 75, which proves that T225NG has an excellent corrosion resistance in loop water. The main reason is that there is an oxide film on the surface of specimens. According to the analysis of energy dispersive spectroscopy （EDS） and X-ray diffraction （ XRD ） , the oxide film consists of TiO2. Therefore, the oxide film at the crack tip impedes the hydrogen separating out from the cathode to penetrate into titanium alloy and resists hydrogen embrittlement.

关键词： titanium alloy stress corrosion oxide film double cantilever beam

Effect of pressurizing speed on filling behavior of gradual expansion structure in low pressure casting of ZL205A alloy

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China Foundry 2018年第4期15卷 276-282页

作者： Shan-guang Liu Chuan-biao Luo Guo-ai Li Wen-lin Gao Zheng Lu Sheng-long Dai Beijing Institute of Aeronautical Materials Beijing 100095China

The mold filling behavior of gradual expansion structure in low pressure casting was studied by two phase flow model using the Volume of Fluid method, and was verified by water simulation with a Plexiglas mold. To get smooth mold filling process and provide a guide for the pressurizing speed design in the producing practice, the mathematical model with the pressurizing speed, expansion angle and height of the gradual expansion structure was established. For validation experiments, ZL205 A alloy castings were produced under two different pressurizing speeds. Weibull probability plots were used to assess the fracture mechanisms under different pressurizing speeds. Mechanical properties of ZL205 A alloy were applied to assess the entrainment of oxide film. The results show that the filling process of a gradual expansion structure in a low pressure casting can be divided into the spreading stage and filling stage by gate velocity. The gate velocity continues to increase in the gradual expansion structure, and increases with the increase of pressurizing speed or expansion angle. Under the effect of the falling fluid raised by the jet flow along the sidewall, the fluid velocity decreases in the jet zone from ingate to free surface. As such, oxide film entrainment does not occur when the gate velocity is greater than the critical velocity, andthe gate velocity no longer reflects the real state of the free surface. The scatter of the mechanical properties is strongly affected by the entrainment of oxide films.

关键词： low pressure casting two phase flow water simulation oxide film ZL205A alloy

Structure Analysis of Oxidation film of Ignition-Inhibition AZ91D Magnesium Alloy Added with Cerium

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Journal of Rare Earths 2003年第1期21卷 73-76页

作者：黄晓锋周宏何镇明 School of Materials Science and Engineering Harbin Institute of Technology Harbin 150001 China School of Materials Science and Engineering Jilin University Changchun 130025 China

The effect of cerium on ignition temperature of AZ91D magnesium alloy was studie d. By the addition of cerium of 1%, the ignition temperature is raised by 180 ℃ , s o the magnesium alloy added with cerium can be melted in air. The burning temper ature increases with the increasing of cerium. The structure and chemical compos itions of the surface oxide film were investigated by XRD and Auger electron spe ctrometry(AES). The results of XRD indicate that the oxide film of the surface o f ignition-inhibition magnesium alloy can change from loose structure of simple magnesia to compact composite structure consisting of magnesia, cerium oxide, M g17 A112 and aluminum oxide, which has excellent ignition-inhibition effect. AE S depth profile analysis shows that the oxide film can be divided into three lay ers. The outside layer is mainly made up of magnesia, the middle layer, which co nsists of cerium oxide, magnesia, and aluminum oxide, is compound and compact. T hermodynamic analysis indicates that the structure of the surface oxide film is accordant to the change of free energy and high vapor pressure of magnesium.

关键词： metal materials ignition-inhibition ceriu m oxide film magnesium alloy rare earths

Numerical Simulation on Nugget Formation and Evolution in Spot Welding of Aluminum Alloy

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Transactions of Tianjin University 2011年第1期17卷 28-32页

作者：程方杰张建优胡绳荪单平 School of Material Science and Engineering Tianjin University Tianjin Key Lab of Advanced Welding and Joining

With the squeeze of electrode tips, the oxide film on aluminum (Al) alloy surface is broken and numbers of micro-gaps are formed randomly. The micro-gaps act as conducting spots at the beginning of welding, so the contact resistance is extremely high and unstable in spot welding of Al alloy. In this paper, a new contact resistance model is adopted to simulate the nugget forming process. This model describes the random distribution characteristic of conducting spots. The simulation results indicate that, within the first 5 ms of welding current (AC, 50 Hz), the temperature distribution at the workpieces interface is seriously irregular. In addition, the nugget does not nucleate from the weld center and grow continuously, however, it nucleates randomly from several points almost instantaneously and then merges into an entity quickly. Experimental results agreed with the numerical simulation.

关键词： aluminum alloy spot welding nugget oxide film contact resistance