刘道新
,
金石
腐蚀学报（英文）
用WOL试样研究了300M钢在35%NaCl水溶液中的应力腐蚀开裂(SCC)特性及阴极极化(偶锌)的影响,并用垂直剖面法测量了断口的分形维数。结果表明,300M钢对中性NaCl水溶液应力腐蚀敏感,阴极极化(CP)明显降低临界应力强度因子,但同时也使平台区裂纹扩展速率(da/dt)Ⅱ显著减小。在本文实验条件下;,断口表面为一近似分形结构,SCC过程是使断裂面降维的过程,在临界应力强度因子附近,自然腐蚀电位(FCP)与CP条件下的断口分维值接近,CP条件下试样中部与近表面断口分维值相近。
关键词:
超高强度钢
,
stress corrosion cracking
,
cathodic polarization
,
fractal dimension
李炳成!南京市210018
,
朱耀庭
,
朱光熹
,
张军
,
林汉同
,
熊国庆
,
沈能芳
材料研究学报
以分维几何学为基础,本文建立了球墨二次电子象的分维布朗模型,提出了以图象处理系统为手段的球墨三维形貌的分维定量度量方法。这种方法能够真实地度量球墨三维形貌,具有对亮度线性变换的不变性,同时还能够很好地揭示球铁的处理工艺与其球墨三维形貌之间的关系。
关键词:
分形
,
fractal dimension
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morpholoy
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grey level
,
pixel
吴小军程文乔生儒邹武张鹏张晓虎
金属学报
将炭毡预制体用化学气相渗法增密至1.0 g/cm3后, 进行树脂浸渍炭化增密. 用压汞法测试了树脂浸渍炭化过程C/C复合材料孔隙率及孔径的变化, 并与完全开孔条件下孔隙变化规律进行了比较. 在此基础上, 提出了树脂浸渍炭化过程孔隙演化模型, 并用分形法进行了表征. 利用SEM观察了不同浸渍炭化次数下C/C复合材料的孔隙形貌. 结果表明: C/C 复合材料树脂浸渍炭化过程中总孔隙率呈下降趋势, 而0.04-6 μm范围的孔隙呈增加趋势, 浸渍炭化过程不断有闭孔孔隙形成. 树脂浸渍炭化过程孔隙演化符合分形, 是一种自相似的填充演化模式, 和本研究提出的孔隙演化模型类似, 孔隙分形维数随浸渍炭化次数呈减小趋势. 首次浸渍炭化后形成了大量的裂纹型孔隙, 随着浸渍炭化次数的增加, 裂纹型孔隙被逐渐填充, 进一步验证了孔隙自相似填充演化模型的合理性.
关键词:
C/C复合材料
,
resin impregnation-carbonization
,
pore
,
fractal dimension
SUN Liling DONG Lianke ZHANG Jishan TANG Yajun ZHANG Jinghua HU Zhuangqi Institute of Metal Research
,
Academia Sinica
,
Shenyang
,
China SUN Liling
,
Institute of Metal Research
,
Academia Sinica
,
Shenyang 110015
,
China
金属学报(英文版)
The morphology of solid/liquid interface of a directionally solidification process is described by means of fractal analysis,and the relations among the fractal dimension of the solid/liq- uid interface,solidification rate,dendrite arm space and the phosphorus content of the test al- loys have been given.It was found that the increase of the solidification rate and the phos- phorus content of the test alloy will lead to a increase,following the regularity of exponential function,in the fractal dimension of solid/liquid interface.Furthermore,by combining the fractal theory and the thermodynamic principle with the measured results,it has been proved that the fractal dimension is not only a kind of simple geometrical parameter used in des- cribing irregular geometry,but also a state function depending the change of solidification parameters and chemical compositions.
关键词:
fractal dimension
,
null
,
null
,
null
,
null
JIANG Xinggang CUI Jianzhong MA Longxiang Northeast University of Technology
,
Shenyang
,
China
金属学报(英文版)
The fractal dimension changes of cavities have been determined during superplastic deformation of the high strength aluminiurn alloy 7475 with different strain,temperature, strain rate and grain size.The fractal dimension of cavities may increase with the increase of strain.It becomes higher as the alloy deformed under lower temperatures,greater strain rate and coarser grain size.The alloy would be approaching to rupture if the fractal dimension of cavities raised to a certain extent.
关键词:
fractal dimension
,
null
,
null
,
null
SU Hui ZHANG Yugui YAN Zhenqi Northeast University of Technology
,
Shenyang
,
China YAN Zhenqi Professor Dept.of Materials Science and Engineering
,
Northeast University of Technology
,
Shenyang 110006
,
China
金属学报(英文版)
By means of fractal analysis,the fractal dimension with relation to the impact toughness,im- pact fracture characteristics and mierostructures of steel under low temperature impact have been investigated.Experimental results show that the logarithms of impact toughness in- creases monotonically with the increase of fractal dimension.The microstruetures have a great influence on fraetal dimension.There is an appropriate correlation between fraetal dimension and fracture mechanism.
关键词:
fractal dimension
,
null
,
null
,
null
