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Ti45Al8Nb0.5B0.2C合金的组织及高温氧化行为研究
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北京市教委高层次人才培养项目 (00900054R8002)


Microstructure and High Temperature Oxidation Behaviour of Ti45Al8Nb0.5B0.2C Alloy
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    摘要:

    研究了Ti45Al8Nb0.8B0.2C合金的组织及高温氧化行为。XRD、SEM、TEM及EDS分析表明, 合金热等静压后的组织为γ和α2相组成的片层组织, 片层团晶粒内部与层片团晶界处存在条状或点状白色相TiB2; 高温淬火合金发生α→γm相变, 在α+γ两相区时效合金组织由不同取向的细小层片和层片交界处的α2相组成。氧化增重实验及XRD、SEM分析表明, 合金在900和1000 ℃氧化100 h, 氧化反应常数分别为0.001 92和0.316 37, 幂指数分别为1.1381和2.0076。合金在900 ℃氧化100 h后氧化层厚度大约为4 μm, 从外到内依次为: 不连续的Al2O3层/Al2O3+TiO2混合层/富Nb层/基体。合金在1000 ℃氧化100 h后氧化层厚度大约为5 μm,从外到内依次为:TiO2/Al2O3+TiO2/氮化物层/基体。

    Abstract:

    Microstructure and high temperature oxidation behaviour of Ti45Al8Nb0.5B0.2C alloy was investigated in this work. XRD, SEM, TEM and EDS analysis demonstrate that as-cast Ti46Al8Nb0.5B0.2C alloy after HIP has fully lamellar microstructure consisting of γ and α2 with point-like or ribbon-like TiB2 distributing in the colony or at grain boundary. When the alloy was treated at 1400 ℃ for 1 h and oil cooled from the single α filed leads to α→γm transformation and γm was aged in the α+γ two-phase field, alpha plates precipitated on all {111} planes of the γm to form fine microstructures. In addition to determination of the oxidation knetics by mass gain measurements, surface and cross-sectional morphologies of oxidizing layer formed was observed by SEM and the present phases in the scales were analyzed by XRD. Results show that oxidation reaction constant and power index for Ti46Al8Nb0.5B0.2C alloy oxidized at 900 ℃for 100 h were 0.00192 and 1.1381, respectively. However, oxidation reaction constant and power index for Ti46Al8Nb0.5B0.2C alloy oxidized at1000 ℃ for 100 h were 0.31637 and 2.0076, respectively. Oxidizing layer of Ti46Al8Nb0.5B0.2C alloy after 900℃, 100 h oxidation was about 4 μm and composed of four layer. The first layer is discontinous Al2O3, the second layer is the mixture of Al2O3 and TiO2, and the last is rich in Nb. Oxidizing layer of Ti46Al8Nb0.5B0.2C alloy after 1000 ℃, 100 h oxidation was about 5 μm and composed of 4 layer. The first layer is TiO2, the second layer is the mixture of Al2O3 and TiO2, and the third layer is nitride layer in sequence.

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苏香林,陈子勇,相志磊,聂祚仁. Ti45Al8Nb0.5B0.2C合金的组织及高温氧化行为研究[J].稀有金属材料与工程,2013,42(6):1178~1184.[Su Xianglin, Chen Ziyong, Xiang Zhilei, Nie Zuoren. Microstructure and High Temperature Oxidation Behaviour of Ti45Al8Nb0.5B0.2C Alloy[J]. Rare Metal Materials and Engineering,2013,42(6):1178~1184.]
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  • 收稿日期:2012-06-27
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