Y. G .Zhang
,
C. Q. Chen (Beijing University of Aeronautics and Astronautics
,
Beijing 100083
,
China)Q. Xu (Beijing Laboratory of Electron Microscopy
,
Chinese Academy of Sciences. Beijing
,
China)M. C. Chaturvedi (The University of Manitoba
,
Winnipeg
,
Manitoba
,
Canada R3T 2N2)
金属学报(英文版)
A two-phase TiAl-based alloy with fully lamellar structure has been deformed al room temperature and the deformed microstructures have been examined in dtails by optical microscopy(OM), scanning electron microscopy(SEM) and transmission electron microscopy(TEM) . Deformation mechanisms in the γ-TiAl phase has been defined and the role of grain boundaries in the deformation and fracture has been assessed Some of the mechanisms of interactions between twinning or gliding dislocations and three types of γ γ domain boundaries or γ α_2 interface in a lamellar grain have been identified and resistance of the various domain boundaries or the interface to the propagation of twinning has been evaluated
关键词:
:TiAl
,
null
,
null
,
null
材料科学技术（英）
Structure and magnetostriction of Dy1-xPrxFe2 (0 less than or equal to x less than or equal to 0.5), Dy0.6Pr0.4(Fe1-yTy)(2) (0 less than or equal to y less than or equal to 0.6), and Tb1-zPrz(Fe0.4Co0.6)(2) (0 less than or equal to z less than or equal to 1.0) alloys (T=Co, Ni) have been investigated. It is found that the matrix of the alloys Dy1-xPrxFe2 is a single phase (Dy, Pr)Fe-2 with MgCu2-type structure and the second phase is (Dy, Pr)Fe-3 when x less than or equal to 0.2. The amount of (Dy, Pr)Fe-3 phase increases with increasing Pr content and becomes the main phase when x=0.4. The matrix of Dy1-xPrxFe2 is found to be the (Dy, Pr)(2)Fe-17 phase with Th2Zn17-type structure when x=0.5. It is found that the amount of the cubic Laves phase (Dy, Pr)(Fe, Co)(2) in the Dy0.6Pr0.4(Fe1-yCoy)(2) increases with increasing Co concentration when 0 less than or equal to y less than or equal to 0.6. The substitution of Ni for Fe is nearly not favorable for the formation of the cubic Laves phase (Dy, Pr)(Fe, Ni)(2) in (Dy1-xPrx)Fe-2. The matrix of (Tb1-zPrz)(Fe0.4Co0.6)(2) is a (Tb, Pr)(Fe, Co)(2) phase with the MgCu2-type cubic Laves structure and a second phase of small amount is (Tb, Pr)(Fe, Co)(3) phase when z less than or equal to 0.2, z=0.5 and 1.0. When 0.23) phase with PuNi3-type structure increases with increasing z and becomes the main phase when z=0.4. When 0.53) phase increases sharply, whereas for 0.62 exhibits a peak when x=0.3. The lambda(parallel to) - lambda(perpendicular to) for Dy0.6Pr0.4(Fe1-yMy)(2) (M=Co, Ni) and Tb1-zPrz (Fe0.4Co0.6)(2) is also examined.
关键词:
Zhijun GUO
,
Zhidong ZHANG
,
Xinguo ZHAO
,
Bowen WANG
,
Dianyu GENG
材料科学技术（英）
Structure and magnetostriction of Dy1-xPrxFe2 (0 less than or equal to x less than or equal to 0.5), Dy0.6Pr0.4(Fe1-yTy)(2) (0 less than or equal to y less than or equal to 0.6), and Tb1-zPrz(Fe0.4Co0.6)(2) (0 less than or equal to z less than or equal to 1.0) alloys (T=Co, Ni) have been investigated. It is found that the matrix of the alloys Dy1-xPrxFe2 is a single phase (Dy, Pr)Fe-2 with MgCu2-type structure and the second phase is (Dy, Pr)Fe-3 when x less than or equal to 0.2. The amount of (Dy, Pr)Fe-3 phase increases with increasing Pr content and becomes the main phase when x=0.4. The matrix of Dy1-xPrxFe2 is found to be the (Dy, Pr)(2)Fe-17 phase with Th2Zn17-type structure when x=0.5. It is found that the amount of the cubic Laves phase (Dy, Pr)(Fe, Co)(2) in the Dy0.6Pr0.4(Fe1-yCoy)(2) increases with increasing Co concentration when 0 less than or equal to y less than or equal to 0.6. The substitution of Ni for Fe is nearly not favorable for the formation of the cubic Laves phase (Dy, Pr)(Fe, Ni)(2) in (Dy1-xPrx)Fe-2. The matrix of (Tb1-zPrz)(Fe0.4Co0.6)(2) is a (Tb, Pr)(Fe, Co)(2) phase with the MgCu2-type cubic Laves structure and a second phase of small amount is (Tb, Pr)(Fe, Co)(3) phase when z less than or equal to 0.2, z=0.5 and 1.0. When 0.23) phase with PuNi3-type structure increases with increasing z and becomes the main phase when z=0.4. When 0.53) phase increases sharply, whereas for 0.62 exhibits a peak when x=0.3. The lambda(parallel to) - lambda(perpendicular to) for Dy0.6Pr0.4(Fe1-yMy)(2) (M=Co, Ni) and Tb1-zPrz (Fe0.4Co0.6)(2) is also examined.
关键词:
YANG Jilian ZHANC Baisheng DINC Yongfan China Institute of Atomic Engergy
,
Beijing
,
ChinaYANG Yingchang ZHANG Xiaodong Peking University
,
Beijing
,
ChinaPAN Shuming General Research Institute for Non-Ferrous Metals
,
Beijing
,
China associate professor
,
P.O.Box 275
,
Branch No.30
,
Beijing 102413
,
China
金属学报(英文版)
The N occupying sites and magnetic structures in R_2Fe_(17)N_x(R=Y,Dy,Nd)are de- termined by neutron diffraction.The effects of the site occupation of N on magnetic properties are discussed primarily.
关键词:
neutron diffraction
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null
,
null
,
null
,
null
,
null
杨继廉
,
张百生
,
丁永凡
,
杨应昌
,
张晓东
,
潘树明
金属学报
用中子衍射法测定了R_2Fe_(17)N_x(R=Y,Dy,Nd)中N的占位及磁结构,初步讨论了N的占位对磁性能的影响
关键词:
中子衍射
,
Curie temperature
,
permanent magnet
Journal of Magnetism and Magnetic Materials
The temperature dependence of the anisotropy field H(A) and the thermal expansion DELTA-l/l0 of R2Fe14X (R = Gd, Lu; X = B,C) were measured by applying the SPD technique for H(A)(T) and a membrane technique for DELTA-l(T)/l0. Comparing Lu2Fe14B and Lu2Fe14C the difference in the temperature dependence of H(A) is associated with the difference in the Invar-like thermal expansion between the two compounds.
关键词:
3d magnetism;anisotropy;gd2fe14b
Communications in Theoretical Physics
By means of both a theory for pressure-induced shifts (PS) of energy spectra and a theory for shifts of energy spectra due to electron-phonon interaction (EPI), the 'pure electronic' PS and the PS due to EPI of R-1 line, R-2 line, and U band of GSGG:Cr3+ at 300 K have been calculated, respectively. The calculated results are in good agreement with all the experimental data. Their physical origins have also been explained. It is found that the mixing-of degree \t(2)(2)(T-3(1))e(4)T(2)> and \t(2)(3) 2E> base-wavefunctions in the wavefunctions of R-1 level of GSGG:Cr3+ at 300 K is remarkable under normal pressure, and the mixing-degree rapidly decreases with increasing pressure. The change of the mixing-degree with pressure plays a key role not only for the 'pure electronic' PS of R-1 line and R-2 line but also the PS of R-1 line and R-2 line due to EPI. The pressure-dependent behaviors of the 'pure electronic' PS of R-1 line (or R-2 line) and the PS Of R-1 line (or R-2 line) due to EPI are quite different. It is the combined effect of them that gives rise to the total PS of R-1 line (or R-2 line). In the range of about 15 kbar similar to 45 kbar, the mergence and/or order-reversal between t(2)(2)(T-3(1))e(4)T(2) levels and t(2)(32)T(1) levels take place, which cause the fluctuation of the rate of PS for t(2)(2)(T-3(1))e(4)T(2) (or t(2)(3) T-2(1)) with pressure. At 300 K, both the temperature-dependent contribution to R-1 line (or R-2 line or U band) from EPI and the temperature-independent one are important.
关键词:
high-pressure effect;spin-orbit interaction;electron-phonon;interaction;d orbital;coupling between t(2)(2)(3T(1))e(4)T(2) and;t(2)(32)E;tunable laser crystal;theoretical calculations;temperature-dependence;thermal broadenings;garnet crystals;cr3+ ions;r-line;cr-3+;luminescence;ruby;spectroscopy
李波
,
张树人
,
钟朝位
材料研究学报
doi:10.3321/j.issn:1005-3093.2008.04.019
研究了BaTiO03-R2O3-MgO(R=La,Ce,Pr,Nd,Sm,Gd,Dy,Ho,Y,Er,Yb)系介质的稀土掺杂效应.结果表明,大半径稀土离子在BaTiO3中形成元素均匀性分布,并促进晶粒的长大;而小半径稀土离子能产生明显的细晶效应,在晶界局部富集而偏析出现焦绿石型第二相晶粒R2Ti2O7.随着镧系收缩,稀土掺杂BaTiO3陶瓷的绝缘电阻率明显提高,而稀土离子在BaTiO3中的固溶度大致呈降低趋势.大半径稀土掺杂材料的ε-T曲线呈现单峰效应且居里点下移,而小半径稀土掺杂材料为双峰效应且居里点上升,△C/C-T稳定性显著提高达到X8R.
关键词:
无机非金属材料
,
钛酸钡
,
稀土氧化物
,
多层陶瓷电容器
,
微区分布
,
第二相
,
固溶度
王超
,
张力
硅酸盐通报
通过调整配方组成,成功制备了R2O-RO-SiO2-B2O3-A12 O3多元系统无锫乳浊釉,重点探讨了釉料化学组成关系对釉面乳浊程度的影响,采用扫描电子显微镜(SEM)研究了釉层微观结构及釉层乳浊机理.结果表明:釉料组成中n(R2O)/n(RO)、n(CaO)/n (MgO)、n(SiO2+ B2O3)/n(Al2O3)对釉面白度及质量影响显著.当n(R2O)/n(RO)在0.38～0.49、n(CaO)/n(MgO)在1.03～2.19、n(SiO2+ B2O3)/n(Al2O3)在12.69 ～18.42范围时,釉面自度高、质量好.釉面乳浊的原因是由析晶与分相共同作用,分相促进了晶体的析出,晶体形状主要为短柱状,尺寸约1～4 im,并以类球状团聚包裹形式分散于釉层中.
关键词:
乳浊釉
,
分相
,
析晶
,
显微结构
Physica Status Solidi a-Applied Research
Nd2-xCexCuO4(x = 0.12 to 0.18)with T(onset) = 17 to 26 K is synthesized from the nominal composition of Nd2-xCexCuO4 + nSrCuO2 (+ nCaCuO2) (n = 1, 2) under standard conditions without high pressure treatment. The sintering temperature, atmosphere, and synthetic procedure are important for the superconductivity of Nd2-xCexCuO4. It is difficult to build up n blocks of SrCuO2, CaCuO2, or CdCuO2 on Nd2-xCexCuO4 so as to add CuO2 layers. In addition, the crystal structure and electrical resistance of Nd2-xCexCuO4 are studied.
关键词:
cu-o system;high-temperature superconductors;compound;pressure;cuprate
