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首页> 外文会议>Symposium Proceedings vol.842; Symposium on Integrative and Interdisciplinary Aspects of Intermetallics; 20041129-1201; Boston,MA(US) >Internal Friction of a High-Nb Gamma-TiAl-Based Alloy with Different Microstructures
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Internal Friction of a High-Nb Gamma-TiAl-Based Alloy with Different Microstructures

机译：具有不同显微组织的高Nbγ-TiAl基合金的内摩擦

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摘要

An intermetallic Ti-46Al-9Nb (at%) alloy with different microstructures (near gamma, duplex, and fully lamellar) was studied by internal friction measurements at 300 K to 1280 K using different frequency ranges: (Ⅰ) 0.01 Hz to 10 Hz and (Ⅱ) around 2 kHz. The loss spectra in range Ⅰ show (ⅰ) a loss peak of Debye type at T ≈ 1000 K which is only present in duplex and fully lamellar samples; (ⅱ) a high-temperature damping background above ≈ 1100 K. The activation enthalpies determined from the frequency shift are H = 2.9 eV for the loss peak and H = 4.1 -4.3 eV for the high-temperature damping background. The activation enthalpies for the visco-elastic high-temperature damping background agree well with values obtained from creep experiments and are in the range of those determined for self-diffusion of Al in TiAl. These results indicate that both properties (high-temperature damping background and creep) are controlled by volume diffusion-assisted climb of dislocations. The loss peak is assigned to diffusion-controlled local glide of dislocation segments which, as indicated by transmission electron microscopy observations, are pinned at lamella interfaces.
机译：通过在300 K至1280 K内使用不同频率范围进行内摩擦测量，研究了具有不同微观结构（近γ，双相和全层状）的金属间Ti-46Al-9Nb（at％）合金：（Ⅰ）0.01 Hz至10 Hz （Ⅱ）约为2 kHz。范围Ⅰ中的损耗光谱显示（ⅰ）在T≈1000 K处的德拜型损耗峰，仅在双相和完全层状样品中存在； （ⅱ）≈1100 K以上的高温阻尼背景。根据频移确定的激活焓对于损耗峰为H = 2.9 eV，对于高温阻尼背景为H = 4.1 -4.3 eV。粘弹性高温阻尼本底的活化焓与蠕变实验获得的值非常吻合，并且处于为Al在TiAl中自我扩散而确定的范围。这些结果表明，这两种性质（高温阻尼本底和蠕变）均受位错的体积扩散辅助爬升控制。损失峰被分配给位错段的扩散控制的局部滑动，如透射电子显微镜观察所示，该位错固定在薄层界面。

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