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CRYStAL　StRUCtURE　OF　A　LONG－PERIOD　ORDERED　PHASE　IN　Fe－C　MARtENSItE　AND　COMPUtER　SIMULAtION　OF　ItS　ELECtRON　DIFFRACtION　PAttERNS

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Acta Metallurgica Sinica(English Letters) 1996年第1期9卷 23-26页

作者： REN Xiaobing WANG Xiaotian K.SHIMIZU t.tadaki(National Laboratory of Solid State Microstructures,Nanjing University Nanjing 210093,China)(School of Materials Science and Engineering,Xi’an Jiaotong University Xi’an 710049,China)(Kanazawa Institute of techn Nanjing Univ Nanjing China

Different structure models of a long-period ordered phase in Fe-C martenstie formed during aging have been checked by computer simulation of electron diffraction(ED) patterns based on these *** results showed that the simulated ED pattern of γ'-FexC(Ⅱ) model proposed by the present authors is in good agreement with experimentally observed ED *** was also confirmed that the incommensurate superperiod stems from the coexistence of several γ'-Fe_xC(H) phases with different *** Fe(144)C(24)(Fe6C) model proposed by Uwakweh et *** ED patterns remarkably different from the experimental ones.

关键词： Fe-C martensite long-period ordered phase crystal structure computer simulation electron diffraction pattern

Effect of Elastic Energy due to Atomic Size Factor on Ordering and Decomposition Behaviour of Binary Solid Solutions

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Journal of Materials Science & technology 1996年第2期12卷 135-142页

作者： Ren, XB Wang, Xt Shimizu, K tadaki, t XIAN JIAOtONG UNIV COLL MAT SCI & ENGNXIAN 710049PEOPLES R CHINA OSAKA UNIV INST SCI & IND RESIBARAKIOSAKA 567JAPAN

A theory recently developed by the present authors is applied to the study of the effect of elastic energy due to atomic size factor on the transformation behaviour of binary solid solutions. It is found that elastic interaction energy (EIE), which is a part of the total elastic energy, plays a key role in both ordering elastic interaction ordering (EIO) and spinodal decomposition. the present study gives a reasonable explanation to the historical dilemmas, ''elastic energy paradox'' and ''atomic size factor paradox''. By solving these confusing problems, the coexistence of ordering (EIO) and decomposition, which has been regarded as impossible by conventional theories, can be well understood. the mechanism is as follows: lowering of elastic energy demands EIO, and such an ordering provides a driving force for spinodal decomposition. therefore, in alloys with large atomic size factor, spinodal decomposition is preceded and induced by ordering. Ordering and spinodal decomposition are thus closely related processes to each other.

关键词： Solid solutions

Elastic Energy and Elastic Interaction Ordering of Binary Solid Solutions

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Journal of Materials Science & technology 1996年第1期12卷 57-68页

作者： Ren, XB Wang, Xt Shimizu, K tadaki, t XIAN JIAOtONG UNIV COLL MAT SCI & ENGN XIAN 710049 PEOPLES R CHINA OSAKA UNIV INST SCI & IND RES IBARAKI OSAKA 567 JAPAN

A theory in the framework of continuum elasticity has been developed to calculate the total contribution of ''atomic size effect'' or ''strain energy effect'' to free energy of binary solid solutions. It is found that elastic free energy consists of two parts: elastic self energy (ESE), and elastic interaction energy(EIE). the former is a function of composition alone, the latter is also a function of atomic configuration. Minimization of total elastic free energy with respect to atomic arrangement results in an ordered arrangement of atoms, which is called elastic interaction ordering (EIO), as it originates from elastic interaction among atoms. EIO is a kind of local ordering within a ''characteristic range'', and it is found to be important in determining the state of solid solutions and structures of superlattices. the present theory also gives good explanation to the coexistence of ordering and decomposition which can not be understood in conventional theories.

关键词： Solid solutions

Origin of Ordering Coupled tweed Microstructures in Alloys with Large Atomic Size Factors

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Journal of Materials Science & technology 1996年第3期12卷 166-174页

作者： Ren, XB Wang, Xt Shimizu, K tadaki, t XIAN JIAOtONG UNIV COLL MAT SCI & ENGNXIAN 710049PEOPLES R CHINA OSAKA UNIV INST SCI & IND RESIBARAKIOSAKA 567JAPAN

A theoretical study is developed on the evolution and mechanism of an ordering coupled phase separation, and on the origin of a resultant tweed microstructure. It is found that long-range elastic interaction among atoms with different atomic sizes plays a key role in the phase separation, and that the evolution of the phase separation is very similar to that of conventional spinodal decomposition except that the separation is dependent on an elastic interaction ordering (EIO). this ''EIO coupled spinodal decomposition'' is shown to exhibit a periodical or tweed microstructure being accompanied by an EIO. It is also found that a large atomic size factor yields a large positive contribution of EIO to spinodal decomposition. Generally, it is thermodynamically and kinetically favorable for the EIO to precede the onset of spinodal decomposition, though the former is not separable from the latter as a whole. We suggest that an initially disordered solid solution undergoes an EIO first, and then the partially ordered solid solution starts to decompose via a spinodal mechanism. Solute-enriched regions increase their degree of order along with an increase in solute content, and solute-depleted regions decrease their degree of order together with a decrease of solute content. the final microstructure is characterized by a periodical array of highly ordered solute-enriched regions and nearly disordered solute-depleted regions. the notion of EIO coupled spinodal decomposition is in general agreement with the transformation behaviour of a large number of alloy systems.

关键词： SPINODAL DECOMPOSItION tItANIUM ALLOYS tI ALLOYS tRANSFORMAtIONS NICKEL LI

偶然发现的左室心尖部"铲形"FDG摄取可能提示心尖肥厚性心肌病

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中华核医学与分子影像杂志 2018年第1期38卷 72-73页

作者：唐军 215021 上海交通大学医学院附属苏州九龙医院核医学科

目的心尖部心肌"黑桃A"样的增厚是心尖肥厚性心肌病(AHCM)的独特征象。该研究调查了日常肿瘤脱氧葡萄糖(FDG) PEt显像中偶然发现的左心室心尖部位"铲形"FDG摄取增高影(SSUA)。方法进行回顾性分析,选出具有左心室心尖部位SSUA的患者。将S... 详细信息

目的心尖部心肌"黑桃A"样的增厚是心尖肥厚性心肌病(AHCM)的独特征象。该研究调查了日常肿瘤脱氧葡萄糖(FDG) PEt显像中偶然发现的左心室心尖部位"铲形"FDG摄取增高影(SSUA)。方法进行回顾性分析,选出具有左心室心尖部位SSUA的患者。将SSUA的形态或放射性强度与心电图、超声心动图和负荷态心肌灌注SPECt显像结果进行比较。AHCM的诊断基于心电图出现巨大反向t波、超声心动图心尖部"铲形"肥厚的厚度以及静息态心肌灌注SPECt显像时心尖部位的显像剂摄取增加。结果 34例患者36次PEt显像中发现有SSUA,17例"铲形"放射性增加较弱,17例增加较强。29例为单独SSUA,5例除SSUA外还伴有弥漫性或局灶性左心室摄取增高,后者中3例证实同时有AHCM和不对称性室间隔肥厚。16例行超声心动图检查的SSUA阳性患者中,13例(81%)诊断为AHCM,另外3例被认为是接近AHCM的患者(心尖室壁厚度14～15 mm)。16例SSUA患者在该研究后的随访中再行PEt显像,11例(69%)仍有SSUA,余5例SSUA几乎消失,但伴有左心室心肌弥漫性摄取增加。SSUA的强度与巨大反向t波(Pt显像中偶然发现的SSUA可能与AHCM有关,尤其在心肌缺血的情况下。在多次FDG PEt显像中重复出现的SSUA可能与不明原因的心肌生理性摄取有关。

关键词：肥厚性心肌病心尖肥厚 FDG PEt 心电图超声心动图心肌灌注SPECt