Author X.A. Zhang1)
,
H.Q. Xia1)
,
Z.T. Wu1)
,
Y.F. Han1)
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R. Shi2) and G.X. Hu2) \= 1) Mechanical Properties Laboratory
,
Beijing Institute of Aeronautical Materials
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Beijing 100095
,
China2) The State Education Commission Open Research Laboratory for High Temperature
金属学报(英文版)
Materials and Testing, Shanghai Jiao Tong University, Shanghai 200030, ChinaManuscript received 18 October 1998 The threestage creep behavior of DD3 single crystal superalloy had been studied. The results show that the creeprupture properties of DD3 single crystal satisfy the requirements for high performance turbine blade application. The influence of crystal orientation on the creeprupture property of DD3 single crystal was tested and discussed. An engineering criterion to evaluate the regimes of secondary and tertiary creep is proposed, and this method gives a reasonable result for practical applications. The fractography and TEM micrography of the tested specimens had been studied, and it is determined that the glidecontrolled creep is the basic creep mechanism of DD3 single crystal at intermediate temperature, but the thermally activated processes become dominant at higher temperature.
关键词:
threestage creep curve
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null
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null
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null
材料科学技术（英文）
The structure, specific heat, magnetic and electrical properties of MnTe(1-x)Sb(x) (x=0, 0.1, 0.15, 0.2 and 0.25) alloys have been investigated. The MnTe(1-x)Sb(x) alloys crystallize in a hexagonal NiAs-type structure, and the impurity of MnSb phase appears when x >= 0.15. The MnTe(0.9)Sb(0.1) compound exhibits ferrimagnetic behavior with hysteresis loops even at 350 K, showing that the magnetic properties of MnTe compound are very sensitive to little compositional change. The ferromagnetism in the MnTe(1-x)Sb(x) alloys with higher Sb contents may be attributed to the impurity of MnSb phase. Energy dispersive X-ray spectroscopy analysis on the MnTe(0.9)Sb(0.1) compound indicates that Sb is very difficult to dope into the lattice of MnTe. So the anomaly of resistivity at 300 K of MnTe(0.9)Sb(0.1) and the peak of specific heat around 304 K of all the alloys are thought to be related with the antiferromagnetic interactions of MnTe-based lattice.
关键词:
Electronic transport property;Hysteresis loop;Specific heat;manganese telluride;semiconductors;ferromagnetism;scattering;exchange
Physical Review B
The temperature dependence of the elastic properties of Ni(2+x)Mn(1-x)Ga and Ni(2)Mn(Ga(1-x)Al(x)) (x = 0.0, 0.1, and 0.2) random alloys are investigated by using the first-principles exact muffin-tin orbitals method. At 0 K, the calculated equilibrium parameters in both cubic L2(1) and nonmodulated tetragonal beta'''-Ni(2)MnGa are in good agreement with the available experimental data and other theoretical results. Separating the thermal effects into single electron excitation, volume expansion, phonon smearing, and magnetic terms, we find that phonon smearing gives the dominating positive tetragonal elastic constant (C') versus temperature (T) slope for the cubic phase. For Ni(2+x)Mn(1-x)Ga, the competition between the negative alloying effect (partial derivative C'/partial derivative x < 0) and the positive temperature effect (partial derivative C'/partial derivative T > 0) leads to nearly constant C'[x, T(M)(x)] at the martensitic transition temperature T(M)(x). For Ni(2)Mn(Ga(1-x)Al(x)), where both partial derivative C'/partial derivative x and partial derivative C'/partial derivative T are positive, however, due to the significantly decrease of T(M)(x), the critical C'[x, T(M)(x)] slightly decreases with Al doping. Furthermore, it is demonstrated that both the composition and the temperature dependence of C' are indispensable to get a reasonable theoretical T(M)(x).
关键词:
shape-memory alloys;ni-mn-ga;martensitic phase-transformation;potential model;heusler alloys;ni2mnga alloy;landau theory;approximation;transitions;disorder
Y.X.Li
,
G.Z.Xu
,
J.P.Qu
,
F.G.Liu and B.W.Wang Hebei University of Technology
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Tianjin 300130
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China C.C.Tang.G.H.Wu and W.S.Zhan State Key Laboratory for Magnetism
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Institute of Physics
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CAS
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Beijing 100080
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China C.Zhao Tianjin University
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Tianjin 300072
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China S.X.Gao Hebei Normal University
,
Shijiazhuang 050091
,
China
金属学报(英文版)
The synthesis and magnetic properties of Pr xCe 1 x Fe 2 have been investigated. The forma tion of Pr xCe 1 x Fe 2 is found to depend strongly on annealing temperature. Pure single phase compound can be synthesized at ambient pressure when x≤0 5. The main phase of the Laves structure can still be observed up to x=0 8. Magnetostriction increases with in creasing x and a largest saturation magnetostriction 200 ppm is observed for x=0.5.
关键词:
magnetostriction
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null
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null
姜勇
,
曾祥勇
,
李广
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杨应平
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汤萍
,
袁松柳
稀有金属材料与工程
用固态反应法制备了名义组分为La(1+x)/3Ba(2-x)/3MnxCu1-xO3(0.8≤x≤1)的系列试样.试样结构的单相性经粉末X射线衍射分析而得以证实,且随Cu的掺杂其结构由未掺杂时的立方对称性转变为正交对称性.输运实验表明:所有试样均经历了半导体到金属的转变,但转变温度TP随掺杂量增加而逐渐移向低温端;外加磁场大大增加了TP附近的导电性,导致TP附近最大磁电阻效应的出现.
关键词:
La(1+x)/3Ba(2-x)/3MnxCu1-xO3
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晶体结构
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输运性质
Journal of Physics D-Applied Physics
Single-phase Tb(1-x)Pr(x)(Fe(0.4)Co(0.6))(1.9)B(0.1)(0 <= x <= 1) compounds have been synthesized by arc melting and subsequent annealing at ambient pressure. The lattice parameter increases while the Curie temperature decreases linearly with increasing Pr content. The saturation magnetization at 5 and 295 K of the Tb(1-x) Pr(x)(Fe(0.4)Co(0.6))(1.9)B(0.1) compounds decreases when x <= 0.5, then increases with further increasing x. The smallest magnetostriction at room temperature (RT) for Tb(0.5)Pr(0.5)(Fe(0.4)Co(0.6))(1.9)B(0.1) is attributed to its total rare-earth moment which is close to zero, due to the antiparallel alignment of the Pr and Tb moments. The normalized RT magnetization and magnetostriction show that Tb(0.2)Pr(0.8)(Fe(0.4)Co(0.6))(1.9)B(0.1) has the smallest anisotropy, which agrees with the easy magnetization direction along < 1 1 1 > for the compounds with x <= 0.8, but along < 1 1 0 > for the compounds with x = 0.9 and 1.0.
关键词:
alloys;prfe2
