Measurement of oxygen atom diffusion in Nb and Ta by anelastic spectroscopy

Materials Research

Luciano Henrique De Almeida²  Kelly Cristina Cezaretto Pires¹  Carlos Roberto Grandini¹  Odila Florêncio¹ 

[1] ,USP Instituto de Física de São Carlos São Carlos SP ,Brazil

关键词: oxygen diffusion;    internal friction;    interstitials;    Nb;    Ta;   

DOI  :  10.1590/S1516-14392005000300003

来源: SciELO

【 摘 要 】

Impurity interstitial atoms present in metals with BCC structure can diffuse in the metallic matrix by jumps to energetically equivalent crystallographic sites. Anelastic spectroscopy (internal friction) is based on the measurement of mechanical loss or internal friction as a function of temperature. Due to its selective and nondestructive nature, anelastic spectroscopy is well suited for the study of diffusion of interstitial elements in metals. Internal friction measurements were made using the torsion pendulum technique with oscillation frequency of a few Hz, temperature interval from 300 to 700 K, heating rate of about 1 K/min, and vacuum better than 10-5 mbar. The polycrystalline Nb and Ta samples used were supplied by Aldrich Inc. The results obtained showed thermally activated relaxation structures due to stress-induced ordering of oxygen atoms around the Nb (or Ta) atoms of the metallic matrix. The results were interpreted by three methods and led to activation enthalpy values for the diffusion of oxygen in Nb and Ta of 1.15 eV and 1.10 eV, respectively.

【 授权许可】

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