徐常明
,
王士维
,
黄校先
,
郭景坤
,
周国红
无机材料学报
doi:10.3724/SP.J.1077.2007.00577
石英是一种重要的结构和功能材料, 在航天飞行器、半导体、电子通讯和光学器件等领域得到重要应用, 但是高温下方石英的析晶限制了它的进一步应用. 本文综述了不同研究人员对不同形态石英与石英基复合材料析晶行为及其差异的研究成果和所持的不同观点, 再从“表面析晶”的角度分别对不同形态石英析晶行为的差异性与不同工艺因素对石英基复合材料的影响机制进行了系统阐述. 最后, 结合作者的工作, 进一步介绍了方石英无定形化方面的最新研究成果.
关键词:
不同形态石英
,
silica matrix composites
,
cristobalite
,
crystallization
,
amorphization
F. Pan
,
F. Zeng
,
B. Zhao
金属学报(英文版)
Ion beam assisted deposition technique (IBAD) was utilized to systematically studyamorphization in binary metal systems of Nb-magnetic element, i.e., Nb-M (M=Fe,Co or Ni). The glass forming range terned as Nb fraction of Nb-Fe system was about34at.% to 56at.%, that of Nb-Co system was about 32at.% to 72at.% and that of Nb-Ni about 20at.% to 80at.%. Similar percolation patterns were found in amorphousalloy films. The fractal dimensions of the percolation patterns approach to 2, whichindicates 2-D layer growth for amorphous phases. It is regarded that the assistedAr+ ion beam duringthe deposition process plays important role for the 2-D layergrowth. Some metastable crystalline phases were obtained in these three systems byIBAD, e.g., bcc supersaturated solid solutions in Nb-Fe and Nb-Co systems, fcc andhcp phases in Nb-Co and Nb-Ni systems. The formation and competing between theamorphous and the metastable crystalline phases were determined by both the phases'thermodynamic states in binary metal systems and kinetics during IBAD process.
关键词:
amorphization
,
null
,
null
,
null
Y.Q. Wu
,
X. Y. Yang and Y.B. Xu (State Key Laboratory for Fatigue and Fracture of Materials
,
Institute of Metal Research
,
The Chinese Academy of Sciences
,
Shenyang 110015
,
China)(Laboratory of Atomic Imaging of Solids
,
Institute of Metal Research
,
The Chinese Academy of Sciences
,
Shenyang 110015
,
China)
金属学报(英文版)
A cross-sectional sample of indentation in [001] silicon was made and a lateral microcrack beneath the indentation was observed by high resolution electron microscope (HREM). The HREM images around the microcrack tip show an alternate distribution of the amorphous and lattice structure. The crack does not propagate by the successive debonding between certain atomic planes, meaning that before a crack completely opens, there may be a stage of amorphization, resulting from severe distortion of lattice.
关键词:
amorphization
,
null
,
null
,
null
,
null
LIANG Guoxian WANG Erde HUO Wencan Harbin Institute of Technology
,
Harbin
,
China Post Box 435
,
Harbin Institute of Technology
,
Harbin 150006
,
China
金属学报(英文版)
Ni_(100-x)Mo_x(x=20,30,38)alloys have been synthesized by mechanical alloying.The structure evolution of powders in mechanical alloying process has been monitored by X-ray diffraction,scanning electron microscopy and transmission electron microscopy analyses.The results show that the Ni_(62)Mo_(38)sample becomes partially amorphous after high energy ball milling,while the Ni_(80)Mo_(20)and Ni_(70)Mo_(30)become non-equilibrium nanocrystals.
关键词:
mechanical alloying
,
null
,
null
,
null
WANG Weihua XIAO Keqin CHU Zhaoqin DONG Yuanda Institute of Solid State Physics
,
Academia Sinica
,
Hefei
,
ChinaWANG Genmiao Centre of Structural Analysis
,
China University of Science and Technology
,
Hefei
,
China
金属学报(英文版)
Amorphous Al_(80)Fe_(20) powder which can hardly be obtained using conventional rapid quenching technique was directly prepared from crystalline Fe and A1 powders by means of mechanical alloying process.The amorphization process was examined by X-ray analysis and Mssbauer spectroscopy,and the thermal behaviour was studied by DSC.The results show that the rate of amorphization is controlled by the diffusion reaction at the interfaces and changes with the milling time.The effect of milling conditions on amorphization by mechanical alloying was al- so investigated.
关键词:
mechanical alloying
,
null
,
null
,
null
李丽娅
,
易健宏
,
李爱坤
,
彭元东
,
夏庆林
中国有色金属学报
doi:10.1016/S1003-6326(11)61292-2
通过X射线衍射法(XRD)、差示扫描量热法(DSC)和磁性测量等方法系统研究Cr3C2含量和快淬速度对SmCo7-x(Cr3C2)x(x＝0.10-0.25)非晶化行为的影响.结果表明,在低的快淬速度下(20 m/s)下,合金主要由SmCo7主相和少量Sm2Co17R相构成,且SmCo7相的晶粒尺寸随着Cr3C2含量x的增加而减小.随着快淬速度的增加,合金的XRD衍射峰强度变弱、衍射峰宽化,表明SmCo7主相的晶粒尺寸随着快淬速度的增加而减小.当快淬速度增加至40 m/s时,SmCo7-x(Cr3C2)x(0.15≤x≤0.25)合金均形成了非晶态结构,合金的磁滞回线表现为软磁性的窄回线,矫顽力为0.004～0.007 T.采用DSC对合金的晶化行为分析表明,在650℃时SmCo7相首先从非晶基体中析出,在770℃时Sm2Co17相析出.
关键词:
SmCo7型永磁材料
,
Cr3C2
,
快淬
,
非晶化
,
磁滞回线
刘昌龙
,
朱智勇
,
金运范
,
王衍斌
,
孙友梅
,
侯明东
,
王志光
,
刘杰
,
陈晓曦
,
张崇宏
原子核物理评论
doi:10.3969/j.issn.1007-4627.2000.04.011
采用多种手段研究了35 MeV/u的Ar离子辐照聚酯(PET)膜产生的微观结构变化．结果表明，辐照使聚酯的化学键断裂并产生了炔端不饱和基团和自由基．断键主要发生在乙二醇残留物、苯环的对位和酯的C-O键上．随着吸收剂量的增加，材料的结晶度逐渐降低，由原始的41.7％减至最高辐照量时的15.0%．研究发现，聚脂的非晶化转变截面与电子能损呈线性关系；断键和非晶化效应主要取决于样品的吸收剂量，并存在一个约4.0 MGy的阈值．
关键词:
高能Ar离子辐照
,
聚酯
,
断键
,
非晶化效应
