WEN Mao LIN Dongliang T.L.Lin Shanghai Jiaotong University
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Shanghai
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China LIN Dongliang Professor
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Shanghai Jiaotong University
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Shanghai 200030
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China
金属学报(英文版)
The dislocation structure of directionally solidified(DS)Rene 80 superalloy during tensile and creep deformation has been studied by TEM.In tensile deformation,γ'shearing occurs by slip of APB-coupled(1/2)<110>dislocation pairs on{111}planes at temperatures below 760℃.and by slip of SISF-seperated(1/3)<112>superpartials which have dissociated on {111}planes into a(1/2)<110>screw superpartial and a(1/6)<112>edge superpartial with an APB in between at temperatures equal to or above 760℃.In creep deformation,γ'shearing occurs again by slip of SISF-seperated(1/3)<112>superpartials which have not dissociated on{111}planes and by diffusive slip of APB-coupled(1/2) <110>dislocation pairs at 760℃,618 MPa.However,no γ'shearing occurs at 980℃,190 MPa.During secondary creep at 760℃,618 MPa or at 980℃,190 MPa,2-dimensional net- works have formed at γ/γ'interfaces,and the strain is mainly the result of diffusion control- led climb of dislocation networks at γ/γ'interfaces.The dependence of secondary creep rate ε upon size a and volume fraction v_■ of cubic γ' has been found to be ■∝α/v_f~(2/3).
关键词:
directional solidification
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null
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null
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null
刘欣艳
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赵煜娟
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夏定国
功能材料
LiNi0.8Co0.2O2是锂离子电池界公认的最有希望取代商业化正极材料LiCoO2的新型正极材料之一.本文所研究的复合正极材料LiNi0.8Co0.2O2是由细小的晶粒构成的球形颗粒,单一相,属于R3m空间群.对复合材料LiNi0.8Co0.2O2的Co-K和Ni-K的XANES分析可知,在600～850℃范围温度对于钴元素的影响不明显,而对于镍元素的影响比较显著,随着Ni-K边位置向高能量移动LiNi0.8Co0.2O2正极材料的放电容量升高.复合材料LiNi0.8Co0.2O2和LiNiO2的Ni-K边XANES相似,表明少量钴的引入对晶体结构的改变不是太多,但是峰的强度较高和峰的位置向高能量移动,表明钴Co对Ni的局域结构进行了调制.
关键词:
LiNi0.8Co0.2O2
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XANES
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正极材料
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局域结构
余历军
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雷闫盈
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陈立宇
机械工程材料
doi:10.3969/j.issn.1000-3738.2007.12.005
采用四点弯曲试样在高频疲劳试验机上对铝基复合层板进行了疲劳试验,采用直流电势法测量裂纹长度,用扫描电镜和光学显微镜观察其疲劳断口及疲劳裂纹形貌,通过对比性试验,考察了组元性能错配和界面结合强度对复合板L-T取向疲劳裂纹扩展行为的影响,并用断裂力学理论对其进行了初步分析.结果表明:性能错配的复合双层板两侧面的疲劳裂纹扩展通过界面产生牵扯作用,扩展速率相对于整体材料发生变化,近似符合混和定则;界面对层合板L-T取向疲劳性能的韧化作用以分层韧化为主,结合强度不同,产生的影响也不一样.
关键词:
复合层板
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疲劳裂纹
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界面结合强度
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性能错配
Electrochimica Acta
Protective composite coatings were prepared on magnesium alloy AZ91D by micro-arc oxidation (MAO) treatment plus a top coating with sealing agent using multi-immersion technique under low-pressure conditions. The corrosion resistance of AZ91D alloy with composite coatings was superior evidently to that with merely MAO film. SEM observations revealed that the sealing agent was integrated with MAO film by physically interlocking; therewith covered uniformly the surface as well as penetrated into pores and rnicro-cracks of MAO film. The anti-corrosion properties in 3.5% NaCl solution of the composite coatings were evaluated by using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurements. Based on the results of chronopotentiometric (E similar to t) and EIS measurements for long time immersion in 3.5% NaCl solution, appropriate equivalent circuits for the composite coatings system were proposed. It follows that due to the blocking effect of the sealing agent in pores and cracks in MAO film, the composite coatings can suppress the corrosion process by holding back the transfer or diffusion of electrolyte and corrosion products between the composite coatings and solution during immersion. (c) 2005 Elsevier Ltd. All rights reserved.
关键词:
composite coatings;MAO film;sealing;magnesium alloy AZ91D;EIS;micro-arc oxidation;impedance spectroscopy;interfacial factors;phosphate coatings;alkaline-solutions;aluminum-alloys;nacl solution;anodic films;mg alloys;part 2
尹绍江
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辛凤英
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齐长发
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陈礼斌
金属世界
doi:10.3969/j.issn.1000-6826.2006.04.018
本文结合唐钢FTSR生产线的实际生产工艺参数,利用Gleeble 3500C热模拟机,分别研究了单道次不同变形温度、变形速率(50%压下率)对高强低合金T510L钢变形抗力和奥氏体微观组织演变的影响及两道次(R1→R2)连续变形后奥氏体微观组织演变.实验表明通过高温大压下量的变形,完全可使该钢种充分发生动态再结晶,细化奥氏体晶粒度.
关键词:
FTSR
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变形温度
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变形速率
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动态再结晶
Materials and Corrosion-Werkstoffe Und Korrosion
Micro-arc oxidation (MAO) has been accomplished on Mg-Li alloy in alkaline polyphosphate electrolytes without and with the addition of 10?g/L?K2TiF6. The surface/cross-section microstructures of the fabricated coatings were analyzed by scanning electron microscope (SEM); the compositions of the fabricated MAO coatings were analyzed by X-ray diffraction (XRD) and energy dispersive X-ray analysis (EDAX); the corrosion behaviors of bare and MAO coated Mg-Li alloys were evaluated using potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) in 3.5?wt% NaCl solution. Novel hybrid MAO coatings which showed hybrid composition of MgF2/Ti2O5/Ti6O11/MgO, as well as hybrid structure of a dense inner layer, a dense outer layer and an intermediate layer with some sealed/semi-sealed pores, had been fabricated on Mg-Li alloy in alkaline polyphosphate electrolytes with the addition of K2TiF6. Meanwhile, the corrosion resistance of the fabricated MAO coatings was improved obviously as the result of the addition of K2TiF6 in the electrolytes. Moreover, the multiple roles of ${\rm TiF}_{{\rm 6}}boolean AND{{\rm 2}{-} } $ on the MAO process accounted for the fabrication of the corrosion-resistant hybrid MAO coatings.
关键词:
corrosion resistance;Mg-Li alloy;micro-arc oxidation;az91d magnesium alloy;corrosion-resistance;phosphate electrolytes;ceramic coatings;zn alloy;silicate;performance;aluminum;behavior
周元鑫
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夏源明
材料科学与工艺
doi:10.3969/j.issn.1005-0299.2001.04.001
利用MTS810试验机和自行研制的冲击拉伸试验装置对T300/Al复合丝实施了不同应变率下的拉伸试验,获得了材料从0.001 s-1到1 300 s-1应变率范围内完整的应力应变曲线.结果表明:T300/Al是一种应变率敏感复合材料,随着应变率的提高,材料的拉伸强度、失稳应变均相应提高,具有明显的应变率强化效应和动态韧性现象,这主要是由铝基体的应变率强化效应和应变率历史效应引起的.根据材料在不同应变率下的试验结果以及对其不同变形阶段机理的分析,提出了弹塑性复合丝束模型,并由此建立了相应的应变率相关的一维统计损伤本构方程,模型拟合结果与试验结果一致.
关键词:
T300/A1复合丝
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应变率效应
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统计模型
