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Texture Evaluation of α_2 Phase in Ti-25Al-10Nb-3V-1Mo Alloy Sheet

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Journal of materials science & Technology 1996年第5期12卷 361-364页

作者： Weimin MAO Yongning YU Hong YANG and Bo SONG (dept. of materials science and Engineering, University of science and Technology Beijing, Beijing 100083, China) dept. of materials science and Engineering University of Science and Technology Beijing Beijing 100083 China

The texture evaluation of α2 phase in Ti-25Al-10Nb-3V-1Mo sheet during rolling and annealing has been investigated by means of microstructure observation and ODF analysis. From the weak initial {1010} (1210) and {0001}(1210) textures a {1210}(1010) texture and a {0001}(uvtw)fibre texture are formed after cold rolling. The {0001} (1210) texture is also strengthened simultaneously. The activation process of slip systems is discussed concerning formation of the rolling texture. Because of the disappearance of {0001} (nvtw) fibre texture the primary recrystallization process should occur and the {1210}(1010) texture forms during annealing

关键词： Al Phase in Ti-25Al-10Nb-3V-1Mo Alloy Sheet Ti Mo Texture Evaluation of

Optical Absorption Characterizations of Porous Al_2O_3Host/NiO Nanocomposites

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Journal of materials science & Technology 1997年第5期13卷 435-439页

作者： Cai, Weili Mo, Chimei Zhang, Lan Li, Yuanhong Yao, Lianzeng dept. of materials science and Engineering University of Science and Technology of China Hefei 230026 China

Porous Al2O3 host/NiO nanocomposites have been prepared by pyrolysis of Ni2(OH)2CO3 inthe nanostructured Al2O3 hosts. Diffuse reflection spectra in the wavelength range of 200 to800 nm were measured. Results show that (1) in each spectrum exist several absorption bandsof nano-NiO. With increasing the pyrolysis temperature from 550 to 1000℃, the numbers ofabsorption bands of NiO increase from 2 to 6 (P1-P6), (2) comparing with optical absorptionbands of single crystal NiO, for porous nanocomposites the P1, P2 and P4 present 'blue shift'and the P3, P5 and P6 exhibit 'red shift'; (3) when the pyrolysis temperature, Tp, is 550℃, theabsorption bands become so weak that only two bands (P1 and P6) can be observed and inverselywhen Tp=1000℃ all six absorption bands of NiO are strong, (4) for porous Al2O3/NiOnanocomposites prepared by pyrolysis at 1000℃ the PF+ caused by the F+ centers in theAl2O3 host moves towards the short wavelength at first with increasing the doping amount ofNiO from 5 to 50 wt pct and then shifts to the long wavelength with further increasing NiO. Inthis paper, the above phenomena and mechanism of the absorption bands of NiO are discussedin detail.

关键词： Nanostructured materials

Choice of Parameters in Morse Potential for Copper

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Journal of materials science & Technology 1996年第6期12卷 473-475页

作者： Yuming WANG (dept. of materials science, Jilin University Changchun 130023, China) dept. of materials science Juin University Changchun 130023 China

The choice of parameters in Morse potential for copper was made by the molecular dynamics modeling. The elastic coefficients C-11, C-44, their temperature coefficients T-C11, T-C44, well as the hydrostatic compression behaviour, i.e. pressure/volume curves have been calculated. The choice of Morse potential parameters can be made by comparing the results with the experimental data. The chosen parameters are greatly different for different simulated properties.

关键词： Copper

STM Study on the Surface Relief and Mechanism of Bainite Transformation

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Journal of materials science & Technology 1996年第4期12卷 249-254页

作者： Yang, ZG Fang, HS Wang, JJ Zheng, YK Li, CM dept. of materials science and Engineering Tsinghua University Beijing 100084 China

Scanning tunneling microscopy (STM) has been first employed to study the surface relief accompanying bainite transformation in a Fe-2.17C-12.18Cr-0.31Si-0.26Mn (wt pct) steel. With the exclusive vertical resolution of STM, we observed that the surface relief associated with bainite is a group of surface reliefs related to subplates, subunits and sub-subunits. As a whole, the relief group is in a tent shape, not of invariant plane strain (IPS) type, which is obviously different from that of martensite, and implying that bainite is not formed by shear mechanism. The fine structure of bainite in Fe-1.0C-4Cr-2.0Si (wt pct) alloy has also been studied with STM and TEM. It is found that the bainite plate is composed of subplates, subunits and sub-subunits. On the basis of the fine structure inside a bainitic ferrite plate observed under STM, a sympathetic-ledgewise mechanism of bainite formation is proposed.

关键词： Steel

Tetragonal Domain Switching via Reversible tm Phase Transformation

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Journal of materials science & Technology 1996年第4期12卷 255-260页

作者： Haiyan ZHU and Zhicheng XU(dept. of materials science and Engineering, Zhejiang University, Hangzhou 310027, China) dept. of materials science and Engineering Zhejiang University Hangzhou 310027 China

Grinding-induced tm phase transformation and the resultant texture in ceria-yttria-doped tetragonal zirconia polycrystals with varied tetragonality have been studied by XRD. It is observed that the reversible tm phase transformation occurs during grinding and the intensity ratio of I(002)t/I(200)t increases with the transformability. The author proposes that the texture induced by grinding at low temperatures is due to the tetragonal variant reorientation via cyclic,reversible tm phase transformation, termed 'transformational domain switching', instead of the ferroelastic one

关键词： Jun Am Chen Tetragonal Domain Switching via Reversible t m Phase Transformation

Model of Stabilizing Continuous Unidirectional Solidification Process

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Journal of materials science & Technology 2001年第1期17卷 107-108页

作者： Hu ZHANG Guowei CHANG Hanqi HU dept.of materials science and Engineering BeiJing University of Aeronautics and AstranauticsBeijing 100083China School of materials science and Engineering University of Science and Technology BeijingBeijing 100083China

The relation of the related parameters concerning the continuous unidirectional solidification process is derived by means of the theoretical analysis of the heat transfer, the theoretical model is verified by experim... 详细信息

关键词： solidification process theoretical model heat transfer

Hybridization between microstructure and magnetization improvement in lead and RE co-doped BiFeO_3

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Journal of Rare Earths 2016年第5期34卷 495-506页

作者： M.A.Ahmed S.F.Mansour S.I.El-Dek M.M.Karamany materials science Lab.(1) Physics Dept.Faculty of ScienceCairo University Physics Department Faculty of ScienceZagazig University materials science and Nanotechnology dept. Faculty of Post Graduate Studies for Advanced SciencesBeni-Suef University Basic science dept. Faculty of EngineeringBritish University in Egypt

The crystal structure,magnetic and electrical properties of Bi（0.96）Pb（0.04） FeO3 and Bi（0.92）Pb（0.04）RE（0.04）FeO3（RE=La,Sm,Dy and Yb）polycrystalline samples were prepared by the flash autocombustion technique.X-ray diffraction（XRD）measurements show that the rare-earth doped compositions crystallized in rhombohedral symmetry of space group R3 *** undoped sample consisted needle shape particles while rare earth substitution preferred platelet like particles as clarified from high resolution transmission electron microscopy（HRTEM）.Morphological features were examined using field emission scanning electron microscopy（FESEM）.Magnetization measurements showed that Yb^3＋ samples possessed the highest room temperature saturation magnetization while when Bi^3＋ ions were substituted by La^3＋ ions,a smaller MS（0.28 emu/g）was *** coexistence of ferroelectric and magnetic transitions was detected using DSC and χM,indicating the multiferroic characteristics of Bi（0.92）Pb（0.04）RE（0.04）FeO3 *** Néel temperature shifted upwards with decreasing the ionic radius of rare earth *** correlation was established between microstructure,morphology and magnetic properties in view of the contribution of magnetocrystalline and shape anisotropy in the magnetic parameters values.

关键词： BiFeO3 multiferroic rare earths anisotropy dielectric conductivity Neel temperature

Sealing Interfaces of Pin in Colour Picture Tube

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Journal of materials science & Technology 1996年第1期12卷 78-80页

作者： Wang, GQ Tang, XY Ma, JS dept. of materials science and Engineering Tsinghua University Beijing 100084 China

interfacial geometric morphology, chemistry and microstructure have been studied by SEM, EDAX, HREM, and XPS. It is found that the oxide scale/metal interface consists of two layers. The first one is amorphous SiO2 growing inward metal matrix, and the second one under the first layer is TiO2 distributing in metal matrix. There is microstructural transition zone at Cr2O3/SiO2 interface, and an atomic mixed zone with 8 nm width at SiO2/metal interface. The transition zone which is saturated with Cr diffusing from oxide scale exists at the oxide scale/glass interface. The reasons why sand-blasting process can improve bonding strength of the oxide scale and the metal are also discussed. The ideal interfaces are proposed finally.

关键词： Television picture tubes

Formation of a FCC Al_(54)Ti_(23)C_(23) Metastable Phase by Ball Milling

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Journal of materials science & Technology 1997年第4期13卷 345-347页

作者： Nianqiang WU Zhizhang LI Guangxin WANG and Jinming MU(dept. of materials science and Engineering, Zhejiang University Hangzhou 310027, China) dept. of materials science and Engineering Zhejiang University Hangzhou 310027 China

The powder mixture of Al, Ti and graphite has been mechanically alloyed in a planetary ball *** structural evolution of as-milled powder sample has been characterized by XRD, DTA. The results show that the amorphous phase is formed first at an early milling stage, then crystallization occurs during further milling, leading to formation of a nanocrystalline fcc metastable phase. In contrast, during annealing the amorphous phase is crystallized to the equilibrium phase instead of the fcc phase. This indicates that crystallization during ball milling is different from that induced by annealing

关键词： Ti FCC Ball Formation of a FCC Al Metastable Phase by Ball Milling