XING Liqian
,
CHEN Xichen
,
Institute of Physics
,
Academia Sinica
,
Beijing
,
ChinaYANG Gencang
,
ZHOU Yaohe
,
Northwestern Polytechnic University
,
Xi'an
,
ChinaGUO Zhenqi
,
Northwestern University
,
Xi'an
,
China XING Liqian
,
Postdoctoral
,
Institute of Physics
,
Academia Sinica
,
Beijing 100080
,
China
金属学报(英文版)
The glass formability of Ni_(75)B_(17)Si_8 melt and the thermostability of this metallic glass formed from the the melt can be enhanced by eliminating the heterogeneous catalystg. The purification was done by cyclical superheating melt in special glasses and subsequently cyclically superheating it in an electromagnetic levitation apparatus. The purified Ni_(75)B_(17)Si_8 amorphous sample sized up to 20 ~ I0 x 0.5 mm was prepared as four times the thickness of unpurified ones.
关键词:
metallic glass
,
null
,
null
,
null
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
LI Guodong
,
D U Ting
,
Central Iron and Steel Research Institute
,
Ministry of Metallurgical Industry
,
Beijing
,
China LI Guodong
,
Department No.16
,
Central Iron and Steel Research Institute
,
Ministry of Metallurgical Industry
,
Beijing
,
100081
,
China
金属学报(英文版)
The thermodynamic properties of Cu-Ce-S and Cu-Y-S liquid solutions were studied by the chemical equilibrium technique at 1200℃. The equilibrium constants and the standard free energies of formation of CeS and YS were determined for the reactions: CeS=[Ce]+[S] and YS = [Y]+[S] . For the solution of Ce_(1) and Y_(l) in pure Cu according to the reactions: Ce_(1)= [Ce] and Y_(1)= [Y] , the standard free energies of solutions were obtained. The first order and second order interaction coefficients between solute elements as well as the activity coefficients γ_(Ce)~0 and γ_Y~0 in liquid Cu were also determined.
关键词:
Cu-Ce-S system
,
null
,
null
F. H.(Sam) Froes
,
C. Suryanarayana
,
and D. Mukhopadhyay (Institute for Materials and Advanced Processes (IMAP)
,
University of Idaho
,
Moscow
,
ID 83844-3026
,
USA)C-G. Li(BlM
,
P.O. Box 81
,
Beijing
,
100095
,
P.R. CHINA)K. Brand(On leave from Institut fur Werkstoffwissenshaft
,
Technische Universitst Dresden
,
07062 Dresden
,
Germany
,
at IMAP)
金属学报(英文版)
Mechanical alloying (MA), a solid-state powder processing method, is a "far from equilibrium" synthesis technique which allows development of novel crystal structures and microstructures, leading to enhanced physical and mechanical properties. The ability to synthesize a variety of alloy phases including supersaturated solid solutions, nanocrystalline structures, amorphous phases and intermetallic compounds themselves is discussed. No extension of solubility using MA has been observed in the intermetallics studied. Nanostructured grains were observed in all compositions. Long time milling generally resulted in amorphous phase formation in large part because of the increase in grain boundary energy/mole with reduced grain size; good agreement with the Miedema model for amorphization was obtained in the Al-Fe system. Generally an anneal was required to form the intermetallic after MA; however,intermetallics with a large negative enthalpy of formation were detected in the MA condition. A study of the hot isostatic pressing of γ-TiAl powders produced by MA demonstrated that full density can be achieved at least 400℃ below the normal temperature required for conventional powder, that is 725℃ or below. Nanometered sized grains (≤100nm)were observed after HIP'ing up to 850℃.
关键词:
: Intermetallics
,
null
,
null
Wei CHEN (Lab. of Semiconductor Mater. Sci.
,
Institute of Semiconductor
,
Chinese Academy of Sciences
,
Beijing
,
100083
,
China)(To whom correspondence should be addressed)Mianzeng SU(Dept. of Chemistry
,
Peking University
,
Beijing
,
100871
,
China)
材料科学技术（英）
The photoluminescence (PL) and photostimulated luminescence (PSL) of BaFBr:Eu phosphors are reported. In the photoluminescence of BaFBr:Eu, the emission of Eu2+ , e-h recombination and Eu3+ have been observed, while in the photostimulated luminescence only the emission of Eu2+ was observed. This phenomenon may be explained well by the suggestion of a two-band model for the host emission in which the host emission energy may transfer to Eu2+. The difference of excitation in those two processes results in different transfer rates which makes the PL and PSL emission different.
关键词:
Senying LIU
,
Rongze HU
,
Dongliang ZHAO and Chongyu WANG(Central Iron and Steel Research Institute
,
Beijing
,
100081
,
China)(To whom correspondence should be addressed)Ping LUO(National Research Cent or Certified Materials
,
Beijing
,
100013
,
China)Zhongjie P
材料科学技术（英）
By use of self-consistent field Xα scattered-wave (SCF-Xα-SW) method, the electronic structure was calculated for four models of Ti4Al14X (X=Al, Fe, Ni and Cu) clusters. The Ti4Al14X cluster was developed based on L12 Al3Ti-base intermetallic compound. The results are presented using the density of states (DOS) and one-electron properties, such as relative binding tendency between the atom and the model cluster, and hybrid bonding tendency between the alloying element and the host atoms. By comparing the four models of Ti4Al14X cluster, the effect of the Fe, Ni or Cu atom on the physical properties of Al3Ti-based L12 intermetallic compounds is analyzed. The results indicate that the addition of the Fe, Ni or Cu atom intensifies the relative binding tendency between Ti atom and Ti4Al14X cluster. It was found that the Fermi level (EF) lies in a maximum in the DOS for Ti4Al14Al cluster; on the contrary, the EF comes near a minimum tn the DOS for Ti4Al14X (X=Fe, Ni and Cu) cluster. Thus the L12 crystal structure for binary Al3Ti alloy is unstable, and the addition of the Fe, Ni or Cu atom to Al3Ti is benefical to stabilize L12 crystal structure. The calculation also shows that the Fe, Ni or Cu atom strengthens the hybrid bonding tendency between the central atom and the host atoms for Ti4Al14X cluster and thereby may lead to the constriction of the lattice of Al3Ti-base intermetallic compounds.
关键词:
ZHANG Ning
,
Central Iron and Steel Research Institute
,
Ministry of Metallurgical Industry
,
Beijing
,
ChinaLUO Yang
,
San Huan New Material Research and Development Center
,
Academia Sinica
,
Beijing
,
China
金属学报(英文版)
According to the experimental data of phase transition taken from DTA, metallography, SEM and microzone composition, two vertical sections of the ternary phase diagram (B=5.88 at.-%, Nd≤45.41 at.-% andNd_2Fe_(14)BNd_(1.1)Fe_4B_4 , B≤44.56 at.-%) have been drawn in detail. It is verified that the crystallization of both Nd_2Fe_(14)B and Nd_(1.1)Fe_4B_4 phase, during cooling from melt, would take peritectic reaction instead of solid-liquid congruent precipita- tion.
关键词:
Nd-Fe-B phase diagram
,
null
YANG Wangyue
,
ZHANG Jishan
,
CHEN Guoliang
,
TIAN Shusen
,
GENG Qingquan Beijing University of Iron and Steel Technology
,
Beijing
,
China. Institute of Metal Research
,
Academia Sinica. Fushun Steel Works
,
Fushun
,
Liaoning
,
China.
材料科学技术（英）
The deformation and fracture behaviour of nickel-base superalloy GH698 with different grain size have been studied at 700℃ under fatigue-creep interaction conditions. Compared with coarse-grained specimens, the grain refining process shows obvious effect on the mechanical behaviour of the alloy, i. e. in F and C zones, the fraction of pure fatigue and creep fracture on fracture surfaces is greatly reduced, which decreases and increases the fracture life in zones F and C respectively, in FC and C zones, creep deformation is greatly restrained by the alternating stress component, which increases the fracture life remarkably. It is also proved that in spite of the difference in microstru- tures such as grain size, for a constant tem- perature, a unique life equation t_r=A~n can be used to predict rupture life within the stress region controlled by the same fracture mode.
关键词:
Ni-base superalloy
,
null
,
null
LUO Zhiping
,
ZHANG Shaoqing
,
SONG DeyuBeijing Institute of Aeronoutical Materials
,
Beijing
,
100095
,
ChinaTANG Yali
,
ZHAO DongshanZhengzhou Institute of Technology
,
Zhengzhou
,
450002
,
China Manuscript received
,
27 April 1994
金属学报(英文版)
In the as-cast Mg-Zn-Zr-Y alloys, the quasicrystal phases show massive and eutectoid plate morphologies. The selected area dijfraction(SAD) revealed that a large pan of the quasicrystals are face-centered icosahedral (FCI), while a small amout of the quasicrystals belong to the simple icosahedral (SI) phase. It was found that in homogenized alloys, a part of the grain boundry phases was dissolved,and small massive W-phase and lath-shape MgZn_(2) phase dispersedly precipitate in the grains. The transformation of the quasicrystals relates to the temperature. After homogenizing at 360 ℃ , the quasicrystals still present, while after homogenizing at 400 ℃ , the quasicrystals transformed into a new C-type orthorhombic phase witha = 0.975 nm, b = 1.137nm and=0.935 nm.
关键词:
Mg-Zn-Zr-Y alloy
,
null
,
null
