Effect of impurities on mechanical relaxation in niobium

Abstract

Measurements of internal friction as a function of temperature were performed in samples of Nb containing different amounts of substitutional (Zr) and interstitial (O, N) solutes. These data were resolved using the method of successive subtraction, into a series of constituent Debye peaks corresponding to different interactions. For each relaxation process we obtained the height (Q-1max) and temperature (Tp) of the peak, the activation energy (E) and the relaxation time (t0). The height, shape and temperature of the peaks depend on the concentration of interstitial and substitutional elements. With the addition of substitutional solute one can observed interactions between the two types of solutes (substitutional and interstitial), showing that the random distribution of the interstitial atoms was affected by presence of substitutional atoms. The peaks observed were associated with matrix-interstitial (Nb-O, Nb-N) and substitutional-interstitial (Zr-O) interaction processes

Influence of Oxygen on the Damping Properties of Nb-Zr Alloys

“…The thermally activated behavior of the internal friction peak can be 124 High Damping Materials II observed from the data of Table 2, and the results obtained for the activation energy by both methods show a good agreement. The values of peak temperatures and activation energies for Nb-O and Nb-N interactions obtained for Nb-1.09 wt% Zr single crystal alloy are in very good agreement with the reported values from several authors [2,5,[13][14][15]. The presence of the substitutional element (Zr) affects the random distribution of the interstitial solute atoms in free solid solution, with oxygen and nitrogen atoms clustering around zirconium atoms, according to the literature [2,3].…”

“…In comparison with unalloyed Nb [15,16], it is observed that zirconium additions reduce and broaden the Snoek relaxation peaks (such as Nb-1.09 wt% Zr single crystal alloy) or even completely remove them (like as Nb-1 wt% Zr polycrystalline alloy).…”

Nióbio Brasileiro: Processamento e Caracterização de ligas para aplicação aeronáutica e aeroespacial. Nitrogênio nas propriedades anelásticas do nióbio e ligas nióbio-zircônio

“…O método da espectroscopia mecânica (SCHALLER, 2001) é baseado em medidas de atrito interno (WELLER, 1981a;1981b;POWERS, 1957;BUNN, 1962), e nos últimos anos vem sendo utilizado para obter os parâmetros de relaxação do defeito, uma vez que, através destes pode-se obter informações a respeito da difusividade (POWERS, 1959;WERT, 1949;1950;FERRO, 1957;FLORÊNCIO, 2003), concentração de solutos intersticiais (ALMEIDA, 2004), limite de solubilidade (HUANG, 1996;BOTTA, 1990), fenômenos de precipitação, discordâncias (MIZUBAYASHI, 1992;1995), interações interstiticiais-intersticiais, interações substitucionais-intersticiais (SZKOPIAK, 1975; CANNELLI, 1994) e outras imperfeições da rede cristalina (NOWICK, 1972;DE BATIST, 1972;TREQUATTRINI, 1999).…”