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

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    , Volume 31 Issue 24 Previous Issue    Next Issue
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    HIGH TEMPERATURE OXIDATION PERFORMANCE OF SUPERALLOY M41
    LI Tiefan; HU Wusheng; SHEN Jianian(State Key Laboratory of Corrosion Science; Institute of Corrosion and Prolection of Metals; Chinese Academy of Sciences; Shenyang 110015)
    Acta Metall Sin, 1995, 31 (24): 527-534. 
    Abstract   PDF (614KB) ( 521 )
    Compared with alloy M17 and K3, high temperature oxidation performance of low segregation cast nickel base superalloy M41 has been investigated by means of isothermial and cyclic oxidation, XRD, SEM, EDXA and X-ray element maps. Results show that oxidation rate of the alloy M41 accelerates with the rise of temperature, but is lower than that of the alloy K3. Scale adherance of the alloy M41 is better than that of the alloy K3 and M17, so its cyclic oxidation performance is superior to that of alloy M17. Oxidation kinetics of alloy M41 obviously deviate from parabolic law, because votilization of CrO3is severe above 1000℃ .The higher temperature is, the more severe volatilization is, so the more obvious deviation is. Volatilization of CrO3 is minor below 1000℃ ,so deviation is small. In transient oxidation stage, the alloy M41 primarily forms oxides of Ni and Cr, and in steady oxidation stage, scale consists mainly of a continuous and compact Cr2O3 at the outer layer and a tree root shaped Al2O3 at the inner oxidation layer. The internal oxidation becomes more severe with the rise of temperature and the prolongation of time.The nearer it is from the outer oxide layer/matrix interface, the more and smaller the particles of internal oxidation are. This article syntheticly analyses the results of experiments.
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    EFFECT OF COLD DEFORMATION ON CRYSTALLIZATION OF ELECTROLESS PLATED AMORPHOUS Ni-P ALLOY
    SHEN Dejiu; WANG Yulin; YU Jinku; SHAO Guangiie; REN Yunlai; ZHANG Ming( Yanshan University; Qinhuangdao 066004)
    Acta Metall Sin, 1995, 31 (24): 535-538. 
    Abstract   PDF (244KB) ( 574 )
    Effect of cold-deformation on crystallization of electroless plated amopohous Ni-P alloy was studied. The results show that the cold deformation promoted crystallization of the alloy. The cold deformation not only reduces thermal stability of the amorphous alloy,but also induces its crystallization in some degree.
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    A HIGH TEMPERATURE Ni-Cr-Co-B BRAZING FILLER ALLOY
    LIU Weiping(Dalian Railway institute; Dalian 116028); ZHUANG Hongshou(BeUing University of Aeronautics and Astronautics; Beijing 100083)
    Acta Metall Sin, 1995, 31 (24): 539-544. 
    Abstract   PDF (424KB) ( 562 )
    For improving the toughness and elevated temperature mechanical properties of brazed superalloy joints, the silicon-free Ni-CrCo-B brazing filler alloys have been developed. The microstructure, melting characteristics and brazing properties of a series of Ni-CrCo-B filler metals were investigated. Mechanical properties at room and elevated temperatures of superalloy joints brazed with the Ni-Cr-Co-B filler metals were evaluated and compared with those of brazed joints with conventional nickel-base filler metals BNi-1a and BNi-5. It was shown that the toughness and high-temperature mechanical properties of the brazed joints made with the developed Ni-Cr-Co-B filler alloys are better than the latter.
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    EFFECTS OF Ti AND TiO_2 ON MICROSTRUCTURE OF IN SITU FORMED CERAMIC PARTICULATES REINFORCED Al COMPOSITES
    MA Zongyi; LU Yuxiong; BI Jing(Institute of Metal Research; Chinese Academy of Sciences; Shenyang 110015)
    Acta Metall Sin, 1995, 31 (24): 545-549. 
    Abstract   PDF (390KB) ( 468 )
    In situ TiB2 particulate reinforced Al(TiB2/Al) and in situ Al2O3, TiB2 particulates mixture-reinforced Al(Al2O3. TiB2/AI) composites were fabricated by reaction pressing of Ti-AI-B and TiO2-Al-B systems. It is indicated that for the Ti-Al-B system, a certain amount of Al3Ti with a size of several ten μm formed in addition to TiB2, most of the in situ formed TiB2 are block-like particulates with a size of 0.1─5.0 μm, and few TiB2 are rod-like and have an aspect ratio of greater than 4. For the TiO2-Al-B system, the formation of Al3Ti is basically inhibited, and the in situ formed Al2O3 and TiB2 are approximate equal-axial particulates with a size of 0.052.0 μm. The different microstructures of two composites are accounted for.
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    QUANTITATIVE TEXTURE ANALYSIS FOR LOW SYMMETRY POLYCRYSTALLINE MATERIALS WITH OVERLAPPING DIFFRACTION PEAKS
    WANG Yandong; XU Jiazhen(Northeastern University; Shenyang 110006)
    Acta Metall Sin, 1995, 31 (24): 550-554. 
    Abstract   PDF (352KB) ( 502 )
    A new algorithm of quantitative texture analysis(QTA), i. e. modified maximum entropy method(MMEM), is proposed and applied to the determination of textures in polycrystalline samples of lower crystal symmery with overlapping diffraction peaks. By introducing directly maximum entropy principle into the least square equations of pole figure inversion, the least square errors between measured and recalculated pole figures, and the optimum of maximum texture entropy may be simultaneously satisfied. Thus, the maximum entropy principle is applied to the entire processes of QTA in frame of harmonic method(HV). The simulated results of ideal fiber texture show that the precise texture vector for the materials with smooth or sharp textures will be obtained by the MMEM from the less number of pole figures.
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