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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

Structure and magnetic properties of vacuum annealed FePt/Ag nano-multilayers

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Chinese science Bulletin 2003年第3期48卷 236-238页

作者： YANG Tao, yu Guanghua, HWANG Pol & ZHU Fengwu department of materials physics, university of science and technology beijing, beijing 100083, china department of materials physics University of Science and Technology Beijing Beijing 100083 China

FePt/Ag)n nano-multilayers were deposited on MgO(100) single crystal with laser ablation and then sub-jected to annealing. FePt L10 grains with (001) texture and a large perpendicular magnetic anisotropy constant Ku of the order of 106 J/m3 were formed. A thick Ag layer is found to be favorable for improving the (111) preferential orientation and decreasing the dispersion of the easy axis for magnetiza-tion. The measurement of time decay of magnetization gave rise to an activation volume as small as 6×10-25 m3, showing the promising perspective of being the recording medium for future high density perpendicular recording.

关键词：磁记录介质真空封装 FePt/Ag纳米复合薄膜结构磁学性质

Surface hardening of Fe-based alloy powders by Nd:YAG laser cladding followed by electrospark deposition with WC-Co cemented carbide

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Rare Metals 2010年第4期29卷 380-384页

作者： WANG Jiansheng,MENG Huimin,yu Hongying,FAN Zishuan,and SUN Dongbai School of materials science and Engineering,university of science and technology beijing,beijing 100083,china School of materials science and Engineering University of Science and Technology Beijing Beijing China

This paper presents the results of a study concerned with the surface hardening of Fe-based alloys and WC-8Co cemented carbide by inte- grating laser cladding and the electrospark deposition processes. Specimens of low carbon steel were processed firstly by laser cladding with Fe-based alloy powders and then by electrospark deposition with WC-SCo cemented carbide. It is shown that, for these two treatments, the electrospark coating possesses finer microstructure than the laser coating, and the thickness and surface hardness of the electrospark coating can be substantially increased.

关键词： laser cladding electrospark deposition surface hardening Fe-based alloy cemented carbide

INFLUENCE OF INITIAL TEXTRUE ON THE COLD ROLLING TEXTURE OF Ti SHEETS

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中国有色金属学会会刊：英文版 1995年第2期5卷 66-70页

作者： Mao, Weimin yu, Yongning Li, Botao(university of science and technology beijing, 100083 beijing) Univ of science and technology Beijing Beijing China

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关键词： Ti Rolling Texture ODF

Strain in solidifying shell of continuous casting slabs

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Journal of university of science and technology beijing 2003年第6期10卷 26-29页

作者： Guosen Zhu, Xinhua Wang, Huixiang yu, and Wanjun WangMetallurgical Engineering School, university of science and technology beijing, beijing 100083, china Metall. Eng. Sch. Univ. of Sci. and Technol. Beijing Beijing 100083 China

Two-dimension unsteady heat transfer model was applied to obtain the surfacetemperature and the shell thickness of continuous casting slabs during the process ofsolidification. On the basis of which, the mathematical model of strain at the interface of solidand liquid steel was set up. Through which, the strain in the solidifying shell under normal andabnormal operation conditions was gained. The results indicate that the strain is small under thenormal operation conditions and the internal crack never happens. However, when the variation of theroll gap is above 2 mm, the strain caused by which is greater than that caused by ***, the total strain exceeds the critical one and the internal crack is the result. So itis of great importance to maintain the fine state of continuous casting machine to avoid theappearance of internal crack.

关键词： internal crack strain bulging unbending continuous casting slab

NON-EQUILIBRIUM SOLUTE SEGREGATION TO AUSTENITIC GRAIN BOUNDARY IN FERRUM-NICKLE ALLOY

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Acta Metallurgica Sinica(English Letters) 2001年第6期14卷 525-531页

作者： P. Wu, D.Y. yu and X.L. He (department of Material physics, university of science & technology beijing, beijing 100083, china) Dept. of Mat. Phys. Univ. of Sci. and Technol. Beijing Beijing 100083 China

The development of non-equilibrium segregation of boron at grain boundaries in Fe-4 0%Ni alloy during continuous cooling process was experimentally observed with boron Particle Tracking Autoradiography (PTA) and Transmission Electron Microscopy (TEM,). The samples with 10ppm boron were cooled at 2℃/s to 1040, 980, 920, 860, 780 and 640℃ respectively after pre-heat treatment of 1150℃ for 15mm with a Gleeble-1500 heat simulating machine, then water quenched to room temperature. The width of segregation layer and boron depletion zone, rich factor and other parameters were measured by a special image analysis system. The experimental results of PTA show that the grain boundary segregation of boron during cooling process is a dynamic process and the development of the non-equilibrium segregation experiences three stages: first increases rapidly from 1150 to 1040℃, then gently from 1040 to 860℃, and rapidly again from 860℃ to 640℃. The width of boron depletion zone increases from about 11μm at 1040℃ to 26μm at 640℃. TEM observation shows that boron precipitates exist at grain boundaries when the samples are cooled to below 860℃. The experimental phenomena are briefly discussed.

关键词： boron grain boundary non-equilibrium segregation

Chemical states of the atoms in magnetic multilayers Ta/NiO_x/Ni_(81)Fe_(19)/Ta and Co/AlO_x/Co

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Chinese science Bulletin 2002年第4期47卷 276-279页

作者： yu Guanghua, ZHU Fengwu & CHAI Chunlindepartment of materials physics, university of science and technology, beijing 100083, china department of materials physics University of Science and Technology Beijing China

Ta/NiOx/Ni81Fe19/Ta and Co/AlOx/Co multilay-ers were prepared by rf reactive and dc magnetron sputter-ing. The exchange coupling field (Hex) and the coercivity (Hc) of NiOx/Ni81Fe19 as a function of the ratio of Ar to O2 during the deposition process were studied. The composition and chemical states at the interface region of NiOx/NiFe were also investigated using the X-ray photoelectron spectroscopy (XPS) and peak decomposition technique. The results show that when the ratio of Ar to O2 is equal to 7 and the argon sputtering pressure is 0.57 Pa, the x value is approximately 1 and the valence of nickel is +2. At this point, NiOx is anti-ferromagnetic NiO and the corresponding Hex is the largest. As the ratio of Ar/O2 deviates from 7, the Hex will decrease due to the presence of magnetic impurities such as Ni+3 or metallic Ni at the interface region of NiOx/NiFe, while the Hc will increase due to the metallic Ni. Al layers in Co/AlOx/Co multilayers were also studied by angle-resolved XPS. Our finding is

关键词： NiOx/NiFe exchange coupling Co/AlOx/Co X-ray pho-toelectron spectroscopy (XPS) chemical states.

Microstructures of laser cladding of intermetallic-ceramic composite coatings

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International Journal of Minerals,Metallurgy and materials 1997年第3期11卷 8-10页

作者： ZHOU Xianglin CHEN Chuanzhong CHANG Chun yu Jiahong HU Hanqi ( department of materials, Shandong university of technology, Jinan 250061, china) (materials science and Engineering School, university of science and technology beijing, beijing 100083, Shandong Univ of technology Jinan China

The microstructures of laser cladding of (Ni-24.5%(atom fraction)Al)+5O%(mass haction)WC coatingsbefore and after aging was comparetively studied by using SEM and TEM. It is shown that dissolving of WC and reprecipitating in the forms of WC and W,Coccurred during laser cladding, and intermetallic γ' (Ni3Al) orderly precipitatefrom metastable supersaturant Ni-matrix solid solution after heat treatment. The structures are favorable for coating'sproperties.

关键词： intermetallic ceramic laser cladding metastable Phase aging

Secondary Hardening, Austenite Grain Coarsening and Surface Decarburization Phenomenon in Nb-Bearing Spring Steel

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Journal of Iron and Steel Research International 2012年第3期19卷 47-51,61页

作者： ZHANG Chao-lei, LIU Ya-zheng, ZHOU Le-yu, JIANG Chao (School of materials science and Engineering, university of science and technology beijing, beijing 100083, china) School of materials science and Engineering University of Science and Technology Beijing Beijing 100083 China

The secondary hardening, the austenite grain coarsening and the surface decarburization phenomenon of Nb-bearing spring steel were investigated, and the effects of niobium on tempered microstructure was studied using scanning electron microscope. The results show that the micro-addition of niobium increases the tempering resistance and produces secondary hardening. The effect of niobium on the size and distribution of cementite particles is one of the primary reasons to increase the hardness after tempering. The grain-coarsening temperature of the spring steel is raised 150 ~C due to Nb-addition. Furthermore, both the secondary hardening and the austenite grain coarsening phenomenon congruously demonstrate niobium begins observably dissolving above 1 100 ℃ in the spring steel. Be- sides, niobium microalloying is an effective and economy means to decrease the decarburization sensitivity of the spring steels.

关键词： spring steel! microalloyingl secondary hardening grain coarsening surface decarburization