Z.Q. Hu
,
W.R.Sun and S.R. Guo(Institute of Metal Research
,
Chinese Academy of Sciences
,
Shenyang 110015
,
China Manuscript received 26 August 1996)
金属学报(英文版)
The effects of the trace elements, P, S and Si,on the solidification, segregation,microstructure and mechanical properties of GH761 and In718 alloys were studied.It was found that the segregation of the P,S and Si can be greatly aggravated or relieved by the precipitation taking place during the solidification. In the heat treated state,P enhances the intergranular precipitation in the GH761 alloy.The refinement of P in In718 alloy causes the appearance of a film-like δphase.Si increases the intergranular precipitation of the M_6C and the Laves Phase in the In718 alloy.P, S and Si play diverse roles in the tensile and the stress rupture properties of the GH761 and In718 alloys. The most striking effect is that P significantly prolongs the stress rupture lives of the GH761 and In718 alloys in a wide range of 0.00050.015 wt% .The mechanisms by which P,S and Si influence the superalloys are discussed in the text.
关键词:
: superalloy
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null
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null
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null
MA Zongyi YAO Zhongkai Harbin Institute of Technology
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Harbin
,
China
金属学报(英文版)
The SiC_w/Al composite prepared by squeeze casting has a combination of superior room temperature specific strength and modulus together with excellent thermal properties.The extrusion can make an improvement on the strength and ductility of the composite from 582 MPa as squeeze casted up to 639 MPa,and on the transformation from isotropic to the anisotropic structure.This seems to be explained by the orientation of whiskers and the densification of dislocations in matrix.TEM observation indicates that the stacking fault is the usual planar defect on the SiC_w surface. composite;;SiC whisker;;Al alloy;;microstructure
关键词:
composite
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null
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null
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null
Solid State Communications
Magnetic anisotropy fields at room temperature of ternary tetragonal compounds of R2Fe14C(R = Lu, Gd, Nd) and R2Fe14B(R = Gd, Nd) were determined by Singular-Point-Detection (SPD) technique. The magnetocrystalline anisotropies of the carbides were found to be larger than those of their corresponding borides, indicating that the outstanding permanent-magnetic properties may be obtained in the R2Fe14C-based alloys.
关键词:
Journal of Physics-Condensed Matter
Quaternary rate-earth-transition-metal boron nitrides, R2Fe14BN0.1 (R = Nd and Sm), have been synthesized by ate melting. The bond of boron nitride (BN) can be broken by are melting to allow combination with rare-earth and transition-metal atoms. The structure and magnetic properties of these quaternary compounds have been studied by means of x-ray diffraction, neutron diffraction, and alternating-current initial-susceptibility and magnetization measurements. The R2Fe14BN0.1 (R = Nd and Sm) compounds have the tetragonal Nd2Fe14B-type structure with space group P4(2)/mnm,. The Curie temperature and magnetic anisotropy of the compound Nd2Fe14B are slightly enhanced by introducing nitrogen into the lattice of Nd2Fe14B. The spin-reorientation temperature of Nd2Fe14BN0.1 is the same as that of Nd2Fe14B.
关键词:
LIU Shicheng Dalian Railway Institute
,
Dalian
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ChinaHAMAGOCHI Yoshikazu KUWANO Hisashi Muroran Institute of Technology
,
Muroran
,
Japan
金属学报(英文版)
The precipitation behaviour of Fe-Cr-Mo and Fe-Cr-W alloys during aging has been ex- perimentally studied.It was found that in the early stage of aging,a metastable R phase pre- cipitated in both alloys,it was transformed into stable μ-phase,Laves-phase,X-phase or σ-phase in the later stages.The crystallographic structure of metastable R-phase is rhombohedral with lattice parameters of a=0.9075 nm and α=74.45°.The chemical compo- sition of R-phase is Fe-(27.5—34.9)Mo-(0—25.5)Cr and Fe-(28.9—33.0)W-(9.36— 21.0)Cr in at.-% in Fe-Cr-Mo and Fe-Cr-W system,respectively.
关键词:
Fe-Cr-Mo alloy
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null
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null
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null
刘世程
,
浜口由和
,
桑野寿
金属学报
研究了Fe-Cr-Mo、Fe-Cr-W合金的时效析出过程,发现在时效初期、两合金系中均有过渡R相析出,过渡R相为菱形点阵,α=0.9075nm,α=74.45°,其成分在Fe-Cr-Mo合金中为Pe-(27.5—34.9)Mo-(0—25.5)Cr,在Fe-Cr-W合金中为Fe-(28.9—33.0)W-(9.36—21.0)Cr(at.-％),时效后期,过渡R相分别向平衡相μ相、Laves相、χ相及σ相转变。
关键词:
Fe-Cr-Mo合金
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Fe-Cr-W alloy
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precipitation
Y.M. Hao
金属学报(英文版)
An approximate calculation of the exchange interaction constant JRT between therore-earth sublattice and the transition metal sublattice in R2Fe17-xAlx (R=Tb, Gd,and Dy) compounds is given by the molecular-field model and the results of neutrondiffraction. The calculated values, -JR,T/k, for Dy2Fe17-xAlx (x=5, 6, 7 and 8),Tb2Fe10Al7, Gd2Fe17-xAlx (x=7, 8) compounds are 8.62K, 8.64K, 9.52K, 10.34Kand 10.66K, 10.65K, and 9.85K, respectively, they are in agreement with the ex-perimental values, -JR,T/k, of Dy2Fe17-xAlx (x=5, 6, 7 and 8), Tb2Fe10Al7 andGd2Fe17-xAlx (x=7, 8) compounds, which are 8.77K, 9.25K, 10.1K, 10.9K and10.35K, 10.1K, and 10.3K, respectively. The origins of the difference between thecalculated and the experimental results are discussed.
关键词:
neutron diffraction
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null
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null
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null
Journal of Applied Physics
The effect of substitution of Ti for Co in compounds R2Co17-xTix (R=Pr or Nd, and x=0.0-2.0) on the structure and the magnetic properties has been investigated. It is found that the solubility of Ti in the compounds R2CO17-xTix (R=Pr or Nd) is around 1.0. The R2Co16Ti (R=Pr or Nd) are isostructures to their parent compounds (rhombohedral), and its unit cell is expanded. The spontaneous magnetization mu(s) and Curie temperature T-c decrease with increasing Ti content, owing to the magnetic dilution and the reduction of the moment of Co sublattice caused by Ti substitution. Moreover, an anomaly in the M-T curves of Pr2Co16Ti and Nd2Co17-xTix compounds with x=0.5 and 1.0 may be attributed to a spin reorientation. This transition may originate from the change of crystal electron field due to the preferential occupation of Ti atoms on specific crystallographic sites. (C) 1997 American Institute of Physics.
关键词:
朱良
,
王晶
,
李晓慧
,
锁红波
,
张亦良
材料研究学报
针对应力比对疲劳寿命影响的问题,以TC18钛合金堆焊成形(利用多层堆焊的方法制备)试样为研究对象,进行了3种应力比(R=0.5、R=0.06、R=-1)的疲劳实验,得出相应的疲劳极限,应用"应力幅值寿命模型"和"三参数寿命模型"得到6条S-N曲线.根据裂纹扩展速率与疲劳寿命的积分关系,以两种疲劳寿命数学模型为基础,系统地研究了应力比(R)与疲劳寿命曲线(S-N)的关系,提出了考虑应力比的疲劳寿命(R-S-N)数学模型.根据本文提出的修正公式,建立了适用TC18钛合金堆焊成形材料的两种R-S-N数学模型,结果表明:用应力幅值寿命模型可对中等疲劳寿命区进行准确的预测,而三参数寿命模型更适合中长寿命区域的预测.提出的两种R-S-N数学模型与实验值吻合良好,并可在工程上预测任意应力比下的疲劳寿命曲线.
关键词:
材料科学基础学科
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应力比
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疲劳寿命
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疲劳极限
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R-S-N数学模型
