J.H.Liu 1) and S.H.Jiang 1) and M.Yao 2) 1) Department of mechanical Engineering
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Engineering college
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Yangzhou University
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Yangzhou 225009
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China 2) Department of Material Science
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Yanshan University
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Qinhuangdao 066000
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China
金属学报(英文版)
By using a self-made thermal fatigue test machine of outer-constraint mode, the influence of top-temperature of thermal cycle T t on thermal stress-strain and thermal fatigue behavior of an industrial pure iron was investigated. The T t was varied from stress/strain 773K to 1073K. The results show that, increasing of T t , the thermal stress-strain cycles can be classified into four types, they are: compressive stress cycle; compressive strain-tensile stress cycle; compressive strain-tensile stress cycle than changing to compressive tensile plastic strain cycle; and finally, compressive tensile plastic strain cycle. It is also revealed that certain relationship does exist between thermal fatigue life and characteristics of thermal stress/strain cycle. When compressive tensile plastic strain cycle were appear by increasing of T t , thermal fatigue life decreasing rapidly. The concept of thermal fatigue transition temperature, and determining method were put up in this thesis.
关键词:
thermal fatigue
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F.C.Zhang 1)
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B.T.Hu 1)
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L.X.Zhang 1) and C.F.Lin 2) 1) Department of Materials Science and Engineering
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Yanshan University
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Qinhuangdao 066004
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China 2) Institute of Metal Research
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The Chinese Academy of Sciences
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Shenyang 110015
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China
金属学报(英文版)
Nano silicon particles can be become nano fibre under low energy electron beam bombarding. The formation of the nano silicon fibre include two stages. At first, on the nano silicon particle surface many silicon atoms are gasified, then these silicon atoms deposit in the place where have more charge on account of the static electrical absorption and the point effect of the charge accumulation , these atoms grow into non crystalline silicon fibres. The second stage is the non crystalline silicon fibres crystallizing. Its crystallizing temperature is about 180℃. The growth mechanism of the nano silicon fibre is vapour solid mode.
关键词:
nano fibre
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ZHANG Xiangyi
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ZHANG Jingwu and ZHENG Yangzeng(Department of Materials Engineering
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Yanshan University
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Qinhuangdao 066004
,
China)Mannscript received 4 September 1995
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in revised form 8 April 1996
金属学报(英文版)
The nanocrystalline structure of annealed Fe73.5 Cu1 W3Si13.5B9 alloy has been investigated by using the XRD and the TEM methods. The relation between the initial permeability and the microstructure of the annealed alloy has been discussed. The crystalline phase in annealed Fe73.5 Cu1 W3Si13.5B9 alloy is the α-Fe(Si) phase with DO3 superstructure. The volume fraction, Si content and degree of order of the αFe(Si) phase increase with increasing annealing temperature. In the temperature range of 490-570℃, the α-Fe(Si) phase has a size of 13 nm, and its grain number increases as the annealing temperature is increased. The DO3 ordered region in the α-Fe(Si) grain is spherical approximately, and its size increases as the annealing temperature increases. The size of the DO3 ordered region is 12.8 nm at the temperature of 570℃,which is close to that of the α-Fe(Si) grain. There is obvious change in the structure of the residual amorphous phase during annealing, and the nearest atomic distance and the short-range order of residual amorphous phase reach maximum and minimum at 530℃, respectively. The initial permeability of annealed Fe73.5 Cu1 W3Si13.5 B9 alloy is not only dependent on the size, volume fraction and Si content of the α-Fe(Si) phase but also related to the structure state of the residual amorphous phase.
关键词:
: Fe_(73.5)Cu_1 W_3Si_(13.5)B_9 alloy
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