Microstructural Characteristics and Creep Behavior of 45XD TiAl Alloys
Microstructural Characteristics and Creep Behavior of 45XD TiAl Alloys
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DOI：
10.2320/matertrans.45.2618
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发表时间：
2004-08
影响因子：
1.2
通讯作者：
Hanliang Zhu;D. Seo;K. Maruyama
中科院分区：
文献类型：
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作者：
Hanliang Zhu;D. Seo;K. Maruyama
采用热处理工艺制备了Ti-45 Al-2Nb-2 Mn +0. 8vol %TiB 2合金的近层片组织和两种细晶全层片组织，并对全层片组织进行了时效处理。显微组织和760°C拉伸蠕变试验结果表明，近层片组织由于其层片间距较粗和在集落边界处存在较多的等轴y晶粒，因而具有较差的抗蠕变性能。细片层间距以及细片层团的尺寸给出了一个主要的贡献，使最小蠕变速率较小的全层TiAl合金。由于时效处理稳定了层状组织，延缓了蠕变过程中的退化过程，因此，与未时效处理的相应样品相比，时效样品表现出较低的最小蠕变速率和较长的蠕变寿命。这些结果表明，一个良好的，以及稳定的全层片组织是一个关键因素，以提高蠕变抗力的TiAl合金在短期和长期蠕变。
A near lamellar microstructure and two fine-grained fully lamellar (FGFL) microstructures in Ti-45Al-2Nb-2Mn+0.8 vol%TiB 2 alloy were prepared by selected heat treatments, and the fully lamellar microstructures were aged for stabilizing the lamellar plates. Microstructural examination and tensile creep tests at 760°C showed that the near lamellar microstructure possessed inferior creep resistance due to its coarse lamellar spacing and its larger amount of equiaxed y grains at colony boundaries. The fine lamellar spacing as well as the fine lamellar colony size gave a major contribution to make the minimum creep rates smaller in the fully lamellar TiAl alloys. Since aging treatments stabilized the lamellar microstructures and delayed the degradation process during creep deformation, the aged samples exhibited lower minimum creep rate and longer creep life than the corresponding samples without the aging treatment. These results suggest that a fine as well as stabilized fully lamellar structure is a critical factor to improve the creep resistance of TiAl alloys in terms of short and long-term creep.