ISSN 0412-1961
CN 21-1139/TG
Started in 1956

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    , Volume 31 Issue 17 Previous Issue    Next Issue
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    LANTHANUM SENSOR AND ACTIVITY OF LANTHANUM IN CARBON SATURATED IRON
    ZOU Kaiyun; WANG Changzhen; (Faculty of Metallurgical Phisical Chemislry; Northeastern Universily. Shenyang 110006) ZHAO Nairen (Northeastern University; Shenyang 110006)
    Acta Metall Sin, 1995, 31 (17): 195-199. 
    Abstract   PDF (371KB) ( 583 )
    Laβ-Al2O3(La2O3·11Al2O3) type solid electrolytes were prepared by direct synthesis method. In the temperature range of 800-1500℃, the complex impedance measurements on Laβ-Al2O3 were carried out. The relationships between conductivities of Lag-Al2O3 and temperature, and the activation energy for conduction were obtained. The results show that the order of magnitude of conductivities is 10-6 to 10-3S·m-3, the value of the activation energy is 2.0 eV.It is believed that the Laβ-Al2O3 is conductor of La3+ by the coulometric titration. Stability of Laβ-Al2O3 is proved by D.T.A.The rare earth La probe was made by using Lap-Al2O3 as solid electrolyte, pure La as reference electrode, Mo wire as electrode wire. It was used to determine the activity of dissolved La in C saturating melten Fe (1450℃) with different La concentration. The results were corresponding to that of oxygen concentration cell EMF determined by oxygen probe.The results show that the order of magnitude of activity of dissolved La is 10-4 to 10-3. After some experiments, the rare earth La probe did not split.
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    PREPARATION AND PROPERTIES OF NANOCRYSTALLINE Ti_(70)Ni_(20)Si_(10) ALLOY
    PING Dehai; (Laborutory of Atornic Imaging of Solids; Inslitute of Metal Research; Chinese Academy of Sciences; Shenyang 110015) XIE Miansheng; JIN Zhixiong; LI Douxing; YE HenKqiang(Laboratory of Atomic Imaging of Solids;Institute of Metal Research; Cthinese Academy of Sciences; Shenyang 110015)
    Acta Metall Sin, 1995, 31 (17): 200-205. 
    Abstract   PDF (459KB) ( 563 )
    Nanocrystalline Ti70ONi20Si10 alloys with average grain sizes in the range of 8─120 nm are prepared by crystallization from amorphous precursor under isothermal heat treatment for 1h in the temperature interval of 500-800℃. X-ray diffraction and TEM analysis indicated that nanocrystalline Ti70Ni20Si10 alloy consists of three phases, i.e., Ti2Ni, Ti5Si3 and α-Ti. The values of Vickers hardness of the nanocrystalline alloy are higher than that of amorphous and as-cast samples, which does not increase linearly with reducing the grain size.
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    APPARENT CRYSTALLIZATION KINETICS OF PARTIALLY AMORPHOUS Fe_(33)Zr_(67), ALLOYS
    SUN Nianxiang; (Institute of Metal Research; Chinese Academy of Sciences Shenyang 110015) LIU Xuedong; LI Shuling; DING Bingzhe; LU Ke(Institute of Metal Research; Chinese A cademy of Sciences; Shenyang 110015)
    Acta Metall Sin, 1995, 31 (17): 206-211. 
    Abstract   PDF (370KB) ( 556 )
    Differential scanning calorimeter(DSC), X-ray diffractometer(XRD) and transmition electron microscopy (TEM) were used to study the crystallization kinetics of partially amorphous Fe33Zr67 alloys. Results show that the grain growth dominated the crystallization process. Although an inhomogeneous distribution of quenched-in nuclei exists in the samples. which is contrary to the basic assumptions of the classical Avrami analysis, the obtained Avrami exponents are still in agreement with the Johnson-Mehl-Avrami (JMA)analysis.
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    MAGNETIC PROPERTIES OF NANOCRYSTALLINE Fe_(74.7-X)Cu_1Nb_xV_(1.8)Si_(13.5)B_9 ALLOYS
    ZHANG Yanzhong; (Shanghai Iron and Steel Research Institute; ShanHhai 200940) NIAN Suzhen; JIN Huijuan; XU Guiqin (Shanghai Iron and STeel Research Instituie; Shanghai 200940 ); YANG XielonK; LI Xiangqing(East China Normal University; Shanghai 200062)
    Acta Metall Sin, 1995, 31 (17): 212-219. 
    Abstract   PDF (567KB) ( 553 )
    The synthetical soft magnetic properties are reported for newly-developed nanocrystalline Fe74.7-xCu1NbxV1.8Si13.5B9( x=1, 1 .5. 2.0) alloys. The levels of high-frequency core loss of the alloy with x=2.0 are as follows: P3/100k=468 kW /m3, P2/200 k=706kW/m3; P2/500k=3620kW/m3 and P0.5/1000k=810 kW/m3, they are lower than those of Fe-Cu-Nb-Si-B nanocrystalline alloys. The high-frequency core losses of three new alloys are much lower than those of the superior power Mn-Zn ferrite H7c4 The temperature dependences of initial susceptibility of new alloy have been investigated. It has been observed that two sharp Hopkinson peaks appear in as-quenched samples during heating. whereas the second Hopkinson peak merely appears in the samples with optimum maqnetic properties.This phenomenon is interpreted by Thomas theory. It has been observed that the assembly of α-Fe(Si) grains with nanometre size exhibits superparamagnetic behaviour and Curie-Weiss type of temperature dependence of initial susceptibity at elevated temperature.
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    PREPARATION OF BULK Al-Fe(MO, Si, B)NANOSTRUCTURED ALLOY BY DIFFUSION REACTION UNDER HIGH PRESSURE
    YAO Bin; (Institute of Metal Research; Chinese A cademy of Sciences; Shenyang 110015)DING Bingzhe; LI Dongjian; WANG Aimin; HU Zhuangqi (State Key Laberatory for RSA; Institute of Metal Research; Chinese Acadeimy of Sciences; Shenyang 110015)(Siping Normal College; Siping 136000)
    Acta Metall Sin, 1995, 31 (17): 220-225. 
    Abstract   PDF (438KB) ( 572 )
    A study on the diffusion reaction of melted Al and (Fe0.99, Mo0.01)78Si9B13 amopohous alloy was carried out under a pressure of 3 GPa at temperature ranging from 570 to 850℃. A bulk Al-Fe(Mo,Si,B) nanostructured alloy composed of a single phase was prepared by heating alternate layers of (Fe0.99, M0.01)78S9B13 amorphous ribbons and pure Al sheets for 20 min under a pressure of 3 GPa at temperatures of 800 to 830℃. Its mean grain size is 22 nm and its lattice is orthorhombic. Its thermostability is fairly good and its hardness is 6.9 GPa.
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    INFLUENCE OF RESIDUAL THERMAL STRAIN ON TENSION AND COMPRESSION BEHAVIORS OF METAL MATRIX COMPOSITES
    LI Wenfong; (Laboratory of Heat Treatment; No. 2 Deportment of Mechanical Engineering. South China University of Technology; Guangzhou; 501641) MENG Jilong (South China University of Technology; GuangzhouJI0641); DU Shanyi(Harbin Institute of Technology; Harbin 150001)
    Acta Metall Sin, 1995, 31 (17): 226-232. 
    Abstract   PDF (505KB) ( 772 )
    Residual thermal strain is an important factor which affects the behaviors of metal matrix composites. The modified equivalent inclusion theory is employed to investigate the influence of the residual thermal strain on the tension and compression behaviors of metal matrix composites quantitatively. The difference between the tension and compression behaviors of noncasting composites has been interpreted. Through the experiment about the tension and compression behaviors of 20% SiCw / Al and the observation of the fracture surface, it is proved that the theoretical model reflects the plastic principle of the whisker reinforced metal matrix composites and indicates the necessity of considering residual thermal strain. The theoretical model provides a method to estimate material behaviors and optimal design.
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    EFFECT OF GRAIN SIZE ON TEXTURE AND STRESS ANALYSIS FOR CUBIC MATERIALS
    YU Ligen; (Research institute for Strength of Metals; Xi'an Jiaotong University; Hi'an 710049) XU Kewei; HE Jiawen; GU Haicheng (Stale Key Laboratory for Mechanical Behaviour of Materials; Xi'an Jiaotong University; Xi'an 710049)
    Acta Metall Sin, 1995, 31 (17): 233-237. 
    Abstract   PDF (345KB) ( 621 )
    The minimum grain size determined by the resolution of X-ray texture analysis and the maximum grain size for linear stress measurement curve were calculated for the quasi-isotropic polycrystal. The results show that in certain grain size range, to which texture analysis are insensitive, stress measurement curve can still be nonlinear. The critical grain sizes for iron material are given to show that for certain grain sizes, when d-sin~2Ψ curve is nonlinear, the effect of grain size should be taken into consideration together with that of texture.
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    PAT STUDY OF EFFECT OF Zr ON DEFECTS IN Ni_3Al ALLOY
    GU Yuefong; DENG Wen; GUO Jianting; (Institute of Meial Research; Chinese A cademy of Sciences; Shenyang 110015)XIONG Liangyue; LIN Dongliang (Institute of Metal Research; Chinese A cademy Sciences. Shenyang 110015)(Shanghai Jiaoiong University; Shanghai 200030)
    Acta Metall Sin, 1995, 31 (17): 238-240. 
    Abstract   PDF (209KB) ( 495 )
    The effects of Zr on the microdefects in polycrystalline Ni3Al alloys have been investigated by positron annihilation technique (PAT). The results showed that the lifetime (t1) of positron (e+) in matrix dilated because some of Zr atoms substituted for Al sublattice distorted lattice; the mean lifetime decreased because the others of Zr atoms segregated at GB changed its structure. If Zr was increased up to 1.2 at.-%.t2 increased considerably and it means that defects with larger free volume formed.
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