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Application of phase diagram calculations to development of new ultra-high temperature structural materials

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中国有色金属学会会刊：英文版 2007年第6期17卷 1396-1404页

作者：杨莹 b.P. bewlay 陈双林 y.A. chang CompuTherm LLC Madison Wisconsin 53719 USA General Electric Global Research Schenectady New York 12301 USA Department of Materials Science and Engineering University of Wisconsin-Madison Madison Wisconsin 53705 USA

In-situ refractory metal intermetallic composites(RMICs) based either on (Nb, Si) or (Mo, Si, b) are candidate materials for ultra-high temperature applications (>1400 ℃). To provide a balance of mechanical and environmental properties, Nb-Si composites are typically alloyed with Ti and Cr, and Mo-Si-b composites are alloyed with Ti. Phase diagrams of Nb-Cr-Ti-Si and Mo-Si-b-Ti, as prerequisite knowledge for advanced materials design and processing development, are critically needed. The phase diagrams in the metal-rich regions of multicomponent Nb-Cr-Ti-Si and Mo-Si-b-Ti were rapidly established using the Calphad (Calculation of phase diagram) approach coupled with key experiments. The calculated isotherms, isopleths, and solidification paths were validated by experimental work. The important heterogeneous multiphase equilibria in both quaternary systems identified will offer engineers the opportunity to develop materials with a balance of properties for high-temperature applications.

关键词：金属间化合高温材料 Mo-Si-b-Ti Nb-Cr-Si-Ti

THEORETICAL PREDICTION OF THE KINETICS CURVES OFPEARLITIC TRANSFORMATION IN HyPO-PROEUTECTOID STRUCTURAL STEELS

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Acta Metallurgica Sinica(English Letters) 1998年第3期11卷 215-224页

作者： Z.G.Li H.b.chang T.y.Hsu Z.y.Xu X.y.Ruan Shanghai Jiaotong Univ Shanghai China

Supposing carbon contents of ferrite phases in pearlite precipitating from austenite in multicomponent steel at temperature T and in Fe-C ystem at T' are the same the pearlite formation temperature diference, can be calculated from the FeX phase diagrams and the equilibrium temperature Al. Using Tp and Fe-C binary thermodynamic model, the driving forces for phase transformation from austenite to pearlite in multicomponent steels have been successfully calculated. Through the combination of simplified Zener and Hillert's model for pearlite growth with Johnson-Mehl equation, using data from known TTT diagrams, the interfacial energy parameter and activation energy for pearlite formation can be determined and expressed as functions of chemical composition in steels by regression analysis. The calculated starting curves of pearlitic transformation in some commercial steels agree well with the experimental data.

关键词： pearlite formation temperature difference interfacial energy parameter activation enerpy for pearlite transformation,Johnson-Mehl equation

THEORETICAL PREDICTION OF PROEUTECTOID FERRITICTRANSFORMATION IN HyPO-PROEUTECTOID STRUCTRAL STEELS

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Acta Metallurgica Sinica(English Letters) 1998年第3期11卷 207-214页

作者： H.b.chang Z.G.Li T.y.Hsu Z.y.Xu X.y.Ruan Shanghai Technical Coll of Metallurgy Shanghai China

Proeutectoid ferrite with carbon content xo precipitating from austenite in a multicomponent steel at temperature T is supposed to be equivalent to proeutectoid ferrite with the same carbon content precipitating from austenite in Fe-C binary system at temperature T'.is described as the temperature difference of proeutectiod ferrite formation, and can be calculated from the Fe-X diagrams and the equilibrium temperature A3. by introducing Tf and basing on the thermodynamic model for Fe-C binary alloy, the driving force for phase transformation from austenite to proeutectoid ferrite in multicomponent steels has been successfully calculated. Through the Johnson-Mehl equation and using the data hem known TTT diagrams, the relationship between the chemical composition and the intedecial edenly packeter as well as activation energy for proeutectoid ferrite formation can be calculated. The starting curves of proeutectoid ferritic transformation calculated in this way in some hypo-proeutectoid structural steels agree well with the erperimental data.

关键词： proeutectoid ferrite formation temperature difference interfacial enerpy parameters activation energy for diffusion Johnson-Mehl equation

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沪宁杭地区城市群发展规划探索

长江流域资源与环境 2005年第3期14卷 267-271页

作者：姚士谋陈彩虹陈爽 william y.b.chang 中国科学院南京地理与湖泊研究所江苏南京210008 美国国务院科学基金会东亚事务处

在全球经济一体化的背景下,世界经济中心是在一批具有重大影响的城市群区域。我国许多省市正在编制城市群规划,出现了城市群潮涌神州的新局面。然而城市群区的空间发展规划需要探索的问题不少。以沪宁杭地区为典型例证,就城市群规划的... 详细信息

在全球经济一体化的背景下,世界经济中心是在一批具有重大影响的城市群区域。我国许多省市正在编制城市群规划,出现了城市群潮涌神州的新局面。然而城市群区的空间发展规划需要探索的问题不少。以沪宁杭地区为典型例证,就城市群规划的指导思想与总体思路、区域空间尺度的研究、各种要素的组合及其城市群规划深层发展等问题,进行初步的探索。在城市群区总体发展的关键要素整合方面提出了三个新观点:①城市发展与自然要素的整合;②重视区域交通要素的组织;③城市群区内经济要素流的合理化。以期引起对此问题的深入研究与实践总结。

关键词：发展规划沪宁城市群规划全球经济一体化研究与实践经济中心总体思路空间尺度自然要素城市发展总体发展区域交通经济要素合理化整合

Coating behavior and surface hardening of Pd_(77)Cu_6Si_(17) thin film metallic glass on AZ31 magnesium alloy

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2013年第12期14卷 898-905页

作者： X.H.DU y.C.chang H.J.PEI b.y.CHEN M.C.KUO J.C.HUANG School of Materials Sciences and Engineering Shenyang Aerospace University Department of Materials and Optoelectronic Science National Sun Yat-Sen University Department of Materials Engineering Kun Shan University

Pd77Cu6Si17(PCS) thin film metallic glasses(TFMGs) with high glass forming ability and hardness were selected as a hard coating for improving the surface hardness of AZ31 magnesium alloy. both microindentation and nanoindentation tests were conducted on specimens with various PCS film thicknesses from 30 to 2000 nm. The apparent hardness and the relative indentation depth(β) were integrated using a quantitative model. The interaction parameters involved and relative hardness values were extracted from iterative calculations. According to the results, surface hardness can be enhanced greatly.b. PCS TFMGs in the shallow region, followed by gradual decrease with increasing β ratio. In addition, specimens with thinner coatings(e.g., 200nm) showed greater substrate-film interaction and those with thick coatings(e.g., 2000nm) became prone to film cracking. The optimum TFMG coating thickness in this study was estimated to be around 200 nm.

关键词： Thin film metallic glass(TFMG) Magnesium alloy Sputtering process Nanoindentation Coating thickness

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中国城市化发展速度界定的初步探索

长江流域资源与环境 2010年第5期19卷 487-492页

作者：吴建楠姚士谋朱天明 william y.b.chang 中国科学院南京地理与湖泊研究所江苏南京210008 中国科学院研究生院北京100039 美国国家基金会中国专家组

纵观我国城市化发展历程,虽然取得了举世瞩目的成就,同时也带来了许多问题,具体表现为城市化快速扩张过程中带来的资源与生态环境压力。阐述了城市化发展的国内外背景,认为城市化过程中的土地资源、水资源、环境容量等是影响城镇健康可... 详细信息

纵观我国城市化发展历程,虽然取得了举世瞩目的成就,同时也带来了许多问题,具体表现为城市化快速扩张过程中带来的资源与生态环境压力。阐述了城市化发展的国内外背景,认为城市化过程中的土地资源、水资源、环境容量等是影响城镇健康可持续发展的重要因素,构成了制约城市发展的综合性支撑体系。对我国城市化道路健康发展的基本策略进行了阐述。在对我国城市化发展速度的主要影响因素进行分析的基础上,根据人均GDP增长和各地区城市发展条件与潜力,通过综合指标分析,对我国不同类型区的城市化发展速度进行了初步界定及趋势分析。

关键词：城市化水平城镇发展发展速度发展战略

Ramanujan-type congruences for broken 2-diamond partitions modulo 3

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Science China Mathematics 2014年第8期57卷 1553-1560页

作者： CHEN william y.C. FAN Anna R.b. yU Rebecca T. Center for Applied Mathematics Tianjin University Center for Combinatorics LPMC-TJKLC Nankai University

The notion of broken k-diamond partitions was introduced by Andrews and ***△k(n)denote the number of broken k-diamond partitions of *** and Paule also posed three conjectures on the congruences of△2(n)modulo 2,5 and *** and Sellers proved the conjectures for modulo 2,and Chan proved the two cases of modulo *** the case of modulo 3,Radu and Sellers obtained an infinite family of congruences for△2(n).In this paper,we obtain two infinite families of congruences for△2(n)modulo 3 based on a formula of Radu and Sellers,a 3-dissection formula of the generating function of triangular number due to berndt,and the properties of the U-operator,the V-operator,the Hecke operator and the Hecke *** example,we find that△2(243n+142)≡△2(243n+223)≡0(mod 3).The infinite family of Radu and Sellers and the two infinite families derived in this paper have two congruences in common,namely,△2(27n+16)≡△2(27n+25)≡0(mod 3).

关键词： broken k-diamond partition modular form Ramanujan-type congruence Hecke eigenform

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太湖16000年来沉积环境的演变

古生物学报 1996年第2期35卷 213-223页

作者：王建江水进刘金陵 william y.b.chang 南京师范大学地理系中国科学院南京地质古生物研究所 CENTER FOR GREAT LUKES AND AQUATS SCIENCE AND SCHOOL OF NATURAL RESORCES AND ENVIRONMENT

通过对太湖钻孔岩芯岩性、结构、构造的剖析及粒度、磁化率的测试，发现冰后期东太湖形成于距今６５００年前。在距今６５００—５８００年，为一水深约２—３ｍ的、经常受到流水作用影响的浅水湖泊。距今约５８００—５７００年，东太... 详细信息

通过对太湖钻孔岩芯岩性、结构、构造的剖析及粒度、磁化率的测试，发现冰后期东太湖形成于距今６５００年前。在距今６５００—５８００年，为一水深约２—３ｍ的、经常受到流水作用影响的浅水湖泊。距今约５８００—５７００年，东太湖曾一度干枯或接近于干枯。距今５７００年以来湖泊变浅，平均水深只有１ｍ左右。由于湖泊变浅，湖底经常遭受波浪的扰动，形成波状层理或透镜状层理。西太湖局部洼地集水成湖的时间比东太湖早，并且水深比东太湖大。在５０００ａＢ．Ｐ，东、西太湖并未连通。东、西太湖的连通及太湖统一水体的形成开始于４０００—３５００ａＢ．Ｐ．。东太湖的成湖及东、西太湖的连通，湖面的扩大与水深的变浅，与冰期后海面上升引起的河谷与洼地沉积充填、淤塞有关。

关键词：太湖演变沉积环境成湖时代古地理学

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东太湖全新世水下河道沉积特征及环境演变

古生物学报 1996年第2期35卷 224-233页

作者：汪永进王建刘金陵 william y.b.chang 南京师范大学地理系中国科学院南京地质古生物研究所 CENTER FOR GREAT LUKES AND AQUATS SCIENCE AND SCHOOL OF NATURAL RESORCES AND ENVIRONMENT

在详细研究东太湖Ｅ２孔全新世沉积基础上，总结和归纳了水下河道的沉积特征和相组合规律。识别出高湖面型和低湖面型两种沉积层序。划分了东太湖晚更新世末以来环境演变阶段：１）１５８８５—６５７５ａＢ．Ｐ．冲积黄土基础上发育而... 详细信息

在详细研究东太湖Ｅ２孔全新世沉积基础上，总结和归纳了水下河道的沉积特征和相组合规律。识别出高湖面型和低湖面型两种沉积层序。划分了东太湖晚更新世末以来环境演变阶段：１）１５８８５—６５７５ａＢ．Ｐ．冲积黄土基础上发育而成的古河道；２）６５７５—５８００ａＢ．Ｐ．高湖面时期水下河道沉积环境；３）５８００ａＢ．Ｐ．后，演化为低湖面型水下河道，并逐渐淤积形成开敞湖缘环境。结合西太湖Ｗ１孔沉积特征和层位对比分析，进而讨论了环境演变的阶段性与中国东部全新世海面升降变化的关系。

关键词：太湖东太湖全新世水下河道环境演变