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Search Results: 1 - 10 of 69022 matches for " 计云萍 "
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珠光体、贝氏体、马氏体相变的形核* Nucleation Mechanism of Pearlite, Bainite and Martensite*  [PDF]
刘宗昌,,任慧平
Material Sciences (MS) , 2013, DOI: 10.12677/ms.2013.32014
Abstract: 研究过冷奥氏体转变产物的形核规律具有重要理论价值。采用20MnCrMo、60Si2CrV等材料,奥氏体化后在不同温度进行等温处理,得珠光体、贝氏体、马氏体等产物,应用QUANTA-400型扫描电镜、JEM-2100透射电镜等观察各种相变的形核。发现:珠光体、贝氏体、马氏体均优先在奥氏体晶界处形核,下贝氏体、马氏体也在晶内形核。珠光体晶核由共析铁素体+共析渗碳体两相组成,共析共生,在700℃~650℃,珠光体临界晶核尺寸r* = 150~70 nm;临界形核功 155~292 J/mol。贝氏体在奥氏体的贫碳区形核,晶核是单相(BF),其临界尺度a* = 16.7~25 nm,临界形核功 2.7 × 102 J/mol。马氏体的临界晶核尺寸约为17~20 nm,形核功约为200~600 J/mol。表明随着温度的降低,临界晶核尺寸越来越小,而形核功越来越大。过冷奥氏体转变产物的形核是一个逐渐演化的过程,符合相变形核的一般规律。 It is significant theoretically to study the nucleation mechanism of the phase transformation products of the supercooled austenite. 20MnCrMo, 60Si2CrV and other material were respectively austenized and isothermal quenched at the different temperature to obtain pearlite, bainite and martensite. The nucleation of the phase transformation products was observed by QUANTA-400 environmental scanning electron microscope and JEM-2100 transmission electron microscope. It is found that pearlite, bainite and martensite can all nucleate at the crystal grain boundary of austenite preferentially, moreover, lower bainite and martensite can nucleate in the austenite crystal grain interior. The pearlite crystal nucleus consists of two phases of eutectoid ferrite and eutectoid cementite, which can coexist. At the temperature range of 700 C - 650 C, the dimension of the pearlite critical nucleus is about 150 - 70 nanometer and the critical nucleation energy is 155 - 292 J/mol. Bainite nucleates in carbon-poor region and the bainite crystal nucleus is single phase (BF). The dimension of the bainite ferrite critical nucleus is 16.7 - 25 nanometer and the critical nucleation energy is 2.7 × 102 J/mol. The dimension of the martensite critical nucleus is 17 - 20 nanometer and the critical nucleation energy is 200 - 600 J/mol. The results show that, with the decrease of the transformation temperature, the dimension of the critical nucleus is becoming smaller and smaller and the critical nucleation energy is getting larger and larger. The nucleation of the phase transformation products of the supercooled austenite is a gradual evolutionary process, which accords with the general rule of the phase transformation nucleation.
马氏体相变唯象“理论”的评述—五评马氏体相变的切变学说
The Commentary on Phenomenological Theory of Martensite Phase Transformation—The Fifth Commentary on Shear Theory
 [PDF]

刘宗昌, , 任慧平
Material Sciences (MS) , 2014, DOI: 10.12677/MS.2014.44018
Abstract:
研究马氏体相变晶体学具有重要理论意义。本文简述并评价了唯象学说,指出:1) 以贝茵应变使母相转变为马氏体,缺乏热力学可能性,贝茵应变B作为计算数据,不可靠; 2) 马氏体浮凸是相变体积变化所致,与切变无关,浮凸普遍为帐篷型(∧),矩阵计算式中的形状应变F与马氏体相变晶体学没有直接的联系;3) 点阵不变切变缺乏热力学可能性,在实际的马氏体相变中不存在简单切变(S)。同样,刚性转动也是虚构的;4) 唯象学说与马氏体相变实际不符,应予摈弃。
It is of theoretical significance to study the crystallography of martensite phase transformation. The phenomenological theory was briefly described and evaluated. The proposed viewpoints are as follows. 1) The transformation from austenite to martensite through the Bain strain lacks of the thermodynamics possibility. Moreover, it is unreliable to use the Bain strain (B) as the calculating data; 2) The surface relief of martensite, which is generally in tent (∧) type, results from the bulk expansion during martensite phase transformation and has nothing to do with the shear. The shape strain (F) in the matrix calculation formula is not directly relevant to the crystallography of martensite phase transformation; 3) The lattice invariance shear is short of the thermodynamic feasibility. No simple shear (S) exists in the actual martensite phase transformation, similarly, the rigid rotation is imaginary; 4) The phenomenological theory doesn’t conform to the reality of martensite phase transformation and should be abandoned.
贝氏体相变时原子的位移
Atomic Displacement during Bainite Transformation
 [PDF]

刘宗昌, , 任慧平
Material Sciences (MS) , 2013, DOI: 10.12677/MS.2013.36044
Abstract:
研究贝氏体相变过程中原子的位移具有重要理论意义。本文综合试验事实理论地分析了过冷奥氏体在中温区发生贝氏体相变时原子位移的方式,并指出在孕育期内,依靠浓度涨落,碳原子扩散位移形成了贫碳区和富碳区。在贫碳区中原子以新旧相化学势之差为驱动力,依靠热激活跃迁形成贝氏体铁素体晶核。从热力学上分析,贝氏体铁素体的形成不是切变过程,从相变动力学和扩散速度分析,也非扩散过程。贝氏体相变中,碳原子扩散,界面铁原子以非协同热激活跃迁方式形成贝氏体铁素体和贝氏体碳化物。
>It is significant theoretically to study the atomic displacement during bainite transformation. The atomic displacement mode during bainite transformation in medium temperature region was synthetically analyzed in theory. It is pointed out that, in incubation period, the carbon-poor areas come into being by carbon atoms diffusion displacement for the concentration fluctuation. In the carbon-poor area, the bainite ferrite crystal nucleus is generated by heat activation transition of the iron atoms under the driving force of the difference between the old and new phase chemical potential. From the view of thermodynamics, the formation of bainite ferrite is not shear. From the aspects of transformation kinetics and diffusion velocity, the formation of bainite ferrite is not diffusion either. In bainite transformation, the displacement mode of carbon atoms is diffusion, but that of the interface iron atoms is non-synergic thermal activation transition, which results in the formation of bainite ferrite and bainite carbide.
稀土Ce对X65管线钢组织和性能的影响
孙昊,,陈林
过程工程学报 , 2010,
Abstract: 通过真空感应炉对X65管线钢进行重新冶炼,采用金相显微镜和扫描电镜进行组织观察,采用微机控制电子式万能实验机和电子式摆锤冲击实验机进行性能检测,研究了稀土Ce对X65管线钢的显微组织和力学性能的影响.结果表明,稀土Ce的加入对钢液有明显的变质作用,使夹杂物变成球状的稀土化合物类夹杂并使晶粒细化,提高了X65管线钢的各项力学性能参数;不同热处理工艺表明,对于X65稀土管线钢,若采用860℃终轧温度并空冷,也能获得良好的力学性能.
Effect of Rare Earth Ce on Microstructure and Properties of X65 Pipeline Steels
稀土Ce对X65管线钢组织和性能的影响

SUN Hao,JI Yun-ping,CHEN Lin,
孙昊
,,陈林

过程工程学报 , 2010,
Abstract: 通过真空感应炉对X65管线钢进行重新冶炼,采用金相显微镜和扫描电镜进行组织观察,采用微机控制电子式万能实验机和电子式摆锤冲击实验机进行性能检测,研究了稀土Ce对X65管线钢的显微组织和力学性能的影响. 结果表明,稀土Ce的加入对钢液有明显的变质作用,使夹杂物变成球状的稀土化合物类夹杂并使晶粒细化,提高了X65管线钢的各项力学性能参数;不同热处理工艺表明,对于X65稀土管线钢,若采用860℃终轧温度并空冷,也能获得良好的力学性能.
速冻保鲜技术用于生姜、地黄、石斛保鲜的实验研究
杨桦,郝近大,易红,,梁爱华,王金华,薛宝
中国中药杂志 , 2000,
Abstract: 目的:研究中药鲜药的保鲜方法。方法:应用速冻保鲜技术,对生姜、地黄、石斛分别进行了保鲜方法的试验和保鲜前后的化学成分测定和药效学比较。结果:保鲜贮存期可达6个月至1a。结论:速冻保鲜技术可适用于根茎类中药鲜药的保鲜。
中药新药研究中多糖含量测定方法探讨

中国中药杂志 , 2014,
Abstract: 该文结合新药申报中多糖测定方法中存在的问题,对多糖测定方法的适应范围、对照品的选择、各成分之间的干扰情况、方法研究进展等方面进行了介绍。作者建议:应根据所含多糖的结构及性质选择合适的检测方法,并进行方法学验证,考查所用显色试剂的稳定性、用量、显色时间、最大检测波长等因素,以增加方法的准确性。在多糖的含量测定中应排除单糖及其他水溶性成分的影响;注意对照品的选择;测定波长的选择;关注中性糖和酸性糖测定时的相互干扰,必要时可加入糖抑制剂排除干扰。对于由不同糖残基构成的杂多糖的测定,由于不同单糖的标准曲线的斜率不同,在选择对照品时建议通过研究搞清组成多糖的单糖种类及比例,按此比例配制成混合对照品制作标准曲线,进行测定。
对矿物药研究中相关问题的思考

中国中药杂志 , 2006,
Abstract: 矿物药自古以来就是中药材的重要组成部分,在中医药学的发展上有其独特的作用。在长期的医疗实践中,先人们总结了许多宝贵的经验。随着科学技术的发展和医疗水平的提高,矿物药的研究逐渐深入系统化、涉及内容广泛,包括药物的成分、理化性质、质量标准、炮制方法、功能主治、配伍和剂型等,尤其是对矿物药治病物质基础的研究,在实际应用和理论探索方面有着重要的意义。笔者在药品审评中发现,在注册申请的中药研究中对矿物药的产地....
新药研究中的中药多糖有效部位常见问题分析

中国中药杂志 , 2006,
Abstract: 近年来,以多糖为有效部位的中药新药申请似有增加趋势,笔者就此类中药新药药学研究中的常见问题讨论如下。1多糖有效部位新药研究中的常见问题及分析1·1有效部位的确定多糖广泛存在于自然界,仅有部分多糖具有医疗价值。目前申报的多糖有效部位中药研究中存在的最大问题就是其有效性问题。多糖的研究一般为对多糖粗提物的生理活性的研究,而多糖粗提取物中又可能含有较多其他成分,仅以多糖提取物的药效研究资料难以充分说明多糖
γ射线辐照灭菌法在中药及其制剂中应用现状和相关问题讨论

中国中药杂志 , 2007,
Abstract: 药品卫生是保证药品质量的重要因素,在药品生产的每一环节都应十分重视。现行生产实践中常用的灭菌方法有热压灭菌法、微波灭菌法、钴60-辐照灭菌法等,每种灭菌方法各有其特点。其中钴60-辐照灭菌法是近40年来发展的一种新的消毒灭菌工艺,其主要优点是:价廉、节能,可在常温下消毒灭菌而不破坏易挥发成分及热敏性物质,穿透力强一般可达40~60cm,消毒均匀、速度快、时间短、操作简单,便于连续作业。因此该技术越来越受到人们的关
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