LI Zheng
,
LIU Honglin
,
CHENG Zhaonian
,
CHEN Nianyi
,
Shanghai Institute of Metallurgy
,
Academia Sinica
,
Shanghai
,
ChinaZHOU Jiaju
,
Institute of Chemical Metallurgy
,
Academia Sinica
,
Beijing
,
China CHEN Nianyi
,
Professor
,
Shanghai Institute of Metallurgy
,
Academia Sinica
,
Shanghai 200050
,
China
金属学报(英文版)
The formability of complex flourides has been studied by chemical bond parameter-pattern recognition method. In a multi-dimensional space spanned by ionic radius, ionic polarizability, electronegativity and ionic charge of the metal elements, the binary complex flouride-forming systems and binary flouride systems without complex flouride formation distribute in different regions with a clear-cut boundary. The mathematical models obtained are useful for new complex flouride predicton.
关键词:
complex flouride
,
null
,
null
XU Yourong
,
GU Qing
,
WANG Deying
,
Shanghai University of Science and Technology
,
Shanghai
,
ChinaGU Jufang
,
Q U Tiancai
,
Shanghai Iron and Steel Research Institute
,
Shanghai
,
China XU Yourong
,
Professor
,
Department of Materials Science
,
Shanghai University of Science and Technology
,
Shanghai 201800
,
China
金属学报(英文版)
The dynamic mechanical behaviours of super low carbon high Mo austenitic stainless steel (00Cr20Nil8Mo6CuN)during hot deformation have been studied by using Formaster-Press hot working simulator. The hot deformation equation, as well as the relationship between peak strain, peak stress and Zener-Hollman parameter, together with the deformation activation energy have been resulted through the experiments.
关键词:
hot deformation
,
null
,
null
,
null
,
null
ZHANG Rong
,
ZHOU Lubin
,
Northwestern Polytechnical University
,
Xi'an
,
ChinaZHENG Wenlong
,
HUA Huizhong
,
Shanghai Research Institute of Materials
,
Shanghai
,
China ZHANG Rong
,
Lecturer
,
Department of Applied Physics
,
Northwestern Polytechnical University
,
Xi'an 710072
,
China
金属学报(英文版)
The behaviour towards corrosion fatigue of low carbon bainite steel with various microstructures after tempered at different temperatures has been examined. The susceptibility of the steel to corrosion fatigue may be improved by tempering at 300℃.
关键词:
corrosion fatigue
,
null
,
null
,
null
Ju LUO
,
Xingzhao DING
,
Benpei CHEN and Jie KONG(Institute of Solid State Physics
,
Academia Sinica
,
Hefei
,
230031
,
China)Yuanda DONG(Dept. of Metallurgy and Materials
,
Shanghai University of Technology
,
Shanghai
,
200072
,
China)
材料科学技术（英）
The development of microstructure of nanometer TiO2 powders prepared by a sol-gel process was systematically studied. Grain growth was mon itored using X-ray diffraction (XRD) and transmission electron microscopy (TEM). and the Debye temperature of anatase crystallites was determined. It was found that the grain size of the powders increased slowly with annealing temperature up to 773 K. but grew rapidly in the temperature range of 773-1273K. The activation energies (Ea) for the growth of anatase crystallites in the two temperature regions were calculated to be 16 and 90 kJ / mol, respectively. The Debye temperatures of nanocrystalline anatase powders were all lower than that of microcrystalline anatase. which implies that the bonding force between Ti and O atoms in nanocrystalline TiO2 shourd be smaller than that in microcrystalline state. However. it was noted that the Debye temperature of nanocrystalline anatase increased with the decrease of grain size. This may be attributed to the enhancement in atomic bonding force due to the existence of high surface tension in nanocrystalline powders
关键词:
Yuanzheng YANG and Xueming MA (Institute of Solid State Physics
,
Academia Sinica
,
Hefei
,
230031
,
China)(To whom correspondence should be addressed)Yuanda DONG(Dept. of Metallurgy arid Materials
,
Shanghai University of Technology
,
Shanghai
,
200072
,
China)
材料科学技术（英）
Mechanical alloying (MA) was employed to produce supersaturated solid solutions of Fe1-xCux,which is virtually immiscible under an equilibrium condition at ambjent temperature. The X-ray diffraction results show that the solutions formed in the concentration ranges of x≤0.1 5 and x≥0.40 are of bcc structure of iron and fcc structure of copper. respectively. For the region in between.however, the alloy obtained is a mixture of bcc plus fcc phases. The Mossbauer spectrum of the solid solution of a single phase could be fitted by two sub-spectra with hyperfine magnetic fields of 200 and 250 kOe. respectively. suggesting that there must exist two forms of coordination in the solution. While to fit the spectrum for the solution with mixed structu re. three Sub-spectra. including a spectrum of α-Fe, should be used. The variation of the Mossbauer spectra of Fe60Cu40 with milling time as well as annealing temperature was systematically studied. This may be ascribed to the changes of the number of nearest neighboring atoms of iron in the processes of formation and decomposition of the solid solution during milling and annealing
关键词:
Yueguang YU
,
Jie FU and Xishan XIE(University of Science and Technology Bejing
,
Beijing
,
100083
,
China)Jialong XU and Chunyong JING(Shanghai Iron and Steel Research Institute
,
Shanghai
,
200940
,
China)
材料科学技术（英）
The segregation behaviour and miclostructure of an alloy 718 VADER ingot in comparison with a VAR ingot were studied. The results show that one serious problem of the alloy 718 VADER ingot is dealing with radial chemistry gradients (especially macro-segregation in Nb). The main factor of Nb gradient forming is the flow of Nb rich fluid through passages among the cellular structures driven by centrifugal force from the rotating mold, Detailed structure and micro-segregation studies on ingots impress us that the VADER process does not show the advantage on the improvement of micro-segregation especially in Nb. The cellular structure produced by the VADER process is no more effective in reducjng Nb micro-segregation during homogenization treatment than the dendritic structure by the VAR process. Experimental results lead us to believe that the VADER process is unsuitable to manufacture alloy 718.
关键词:
Lin LIU(Institute of Solid State Physics
,
Academia Sinica
,
Hefei
,
230031
,
China)Yuanda DONG(Dept. of Metallurgy and Materials
,
Shanghai University of Technology
,
Shanghai
,
200072
,
China)
材料科学技术（英）
The structure of rapldly quenched Al-Si alloys (1 and 4 wt-%Si) was systematically studied by optical and transmission electron microscopy (TEM ) as welI as X-ray djffractjon (XRD). ExperimentaIresults show that rapid solidification refines the grain size. extends the solid solubility of Si in Al and Introduces a high density ot defects which exist in the forms of vacancies, dislocations and dislocation loops. etc.. The decomposition process of the alloys was fol lowed by using differential scanning calorimeter (DSC) and the activation energy for precipitation of Si was obtained through Kissinger analysis. The precipitation behaviour of Supersaturated Si in both samples was further examined by TEM. It was found that Si mainly precipitated inside the grains in Al-1 wt-%Si alloy. while in Al-4 wt-%Si alloy. nearly all the Si precipitates distributed along the grain boundaries. This may be due to the structure difference between the alloys in as-quenched state
关键词:
XIE Gang
,
QIU Zhuxian
,
XU Chi
,
CHEN Nainyi Northeast University of Technology
,
Shenyang
,
China. Shanghai Institute of Metallurgy
,
Academia Sinica
,
Shanghai
,
China. To whom correspondence should be addressed.
材料科学技术（英）
Monte Carlo calculations were performed on liquid ionic solution of saturated alumina in cryolite melt containing a total of 205 ions. The local structure and radial distribution functions of the melt were computerized by Monte Carlo method at 1283 K. It has been found that there exist the complex ionic clusters such as AlOF_3~(2-), AlOF_4~(3-), AlF_4~-, AlF_5~(2-), AlOF_2~- etc., as well as oxygen-bridge and flourine-bridge ionic clusters. In the melt studied, Al~(3+) ions tend to have preferential even coordination number of 4F~- ions.
关键词:
Monte Carlo method
,
null
,
null
,
null
,
null
Xiaojing WAN
,
Jiahong ZHU
,
Kailiang JING
,
Weijie CHEN and Yue WU(Institute of Metallurgy and Materials Science
,
Shanghai University of Technology
,
Shanghai
,
200072
,
China)
材料科学技术（英）
Environmental embrittlement in A3B-type intermetallics based on Ni3Al and Fe3Al has been studied in this paper. For the Ni3Al doped with 120 wt ppm B and Ni,(Al,Cr.Zr) doped with 80 wt ppm B,their elongation and ultimate tensile strength decreased in the sequence:of vacuum > air >hydrogen. while for Ni,(Al,Mn) doped with 400 wt ppm B no envifonmental degradation was ob served, although a -Ni3(Al,Mn) alloy without B showed a decrease in ductility when tested in air in stead of oxygen. It is supposed that boron and hydrogen compete for the occupation of interstitial sites near grain boundaries. If boron content is sufficiently low, hydrogen embrittlement occurs ;however, if its content is sufficiently high. boron addition is capable of eliminating envjronmental ef fect in Ni3Al-based alloysi As to the micromechanism of hydrogen embrittlement in Ni3Al+B. S EM in situ observations showed that both grain boundary decohesion and a high stress concentration con tributed to hydrogen-assisted jntergranu lar cracking in this alloy. For the Fe3Al and Fe3 (Al.Cr) alloys.their mechanical properties depended strongly on grain size / grain shape and testing environment. A strain rate effect on ductiIity and fracture strength was also observed in the Fe3Al and Fe,(Al,Cr)+B aIloys. Preoxidation increased the ductility of the Fe,(Al,Cr)+B alloy. All these results can be rationalized from a hypothesis that surface reaction is the controlling process in embrittling Fe3Al-based alloys.
关键词:
