Substitutional-interstitial interactions in niobium-titanium alloys: An internal friction study

Cantelli, R.; Szkopiak, Z.C.

doi:10.1007/bf00903952

Cited by 23 publications

(17 citation statements)

References 8 publications

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“…As shown in Figure 4 the activation energy of Ti-O relaxation in the alloy is 1.25 eV with the peak temperature at 463 K (f = 1 Hz, 1 K min -1 heating rate). [13] For the investigated Ti-Nb-O alloys, the activation energy for the Snoek damping peak is 1.46 and 1.64 eV for 1.5 O and 3.0 O alloys, respectively. It is obvious that a high oxygen concentration will cause the Snoek damping peak to shift to higher temperatures in Ti-Nb-O alloys.…”

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Snoek‐Type High‐Damping Alloys Realized in β‐Ti Alloys with High Oxygen Solid Solution

et al. 2006

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High-damping alloys are finding more and more applications as a passive damping measure in mechanical structures in attempts to eliminate noise and vibration, especially in circumstances where traditional structural damping or system damping methods are not suitable, for example, in high-temperature environments.[1] High-damping alloys have the ability to damp out noise and vibration, and are expected also to possess adequate mechanical properties such as rigidity and strength. In high-temperature working environments, both high damping capacity and strength at elevated temperatures are required. The damping capacity of high-damping alloys (equivalent to the internal friction of a material) is defined as the capacity of a material to convert its mechanical energy of vibration into heat, which is dissipated in the material. With the exception of thermoelastic damping, the majority of damping mechanisms are associated with the stress-induced movement of crystalline defects. Point defects give rise to damping in the range of low to intermediate levels, dislocations give rise to damping levels in the intermediate to high range, and planar defects (twin boundaries and magnetic domain boundaries) give rise to damping levels in the high range.[2] Three groups of high-damping alloys have been developed in the past 50 years, which apply the mechanisms of dislocation damping, ferromagnetic damping, and twinboundary damping, respectively. However, there are some deficiencies in the damping behavior of the alloys, which have affected the application of high-damping alloys. In the case of dislocation-type damping alloys, rearrangement of the pinning points during continued vibration leads to a damping capacity that varies with service time. [2] Similarly, for twin boundarytype damping alloys, it is reported that degradation of damping capacity occurs when they are held at room temperature, which is induced by the diffusion of interstitial carbon atoms to the twin boundaries.[3] And for ferromagnetic high-damping alloys, the damping capacity will be considerably reduced in the presence of a magnetic field or a static load. While the optimization of the damping microstructure is an important research topic for the already developed high-damping alloys, [4][5][6] it is noted that both dislocation damping and boundary damping are influenced by the interstitial impurities in the alloys. While interstitial impurities are easily introduced into the alloys in the conventional fabrication processes, no work has been done to show the advantage of interstitial solid solution atoms in improving the damping capacity of those alloys. We took up the challenge of obtaining a high damping capacity in alloys by making use of the interstitial solid solution atoms. Point defects in crystalline solids can generate a time-dependent strain under the application of an external stress due to the reorientation of the point defects. This phenomenon was experimentally investigated in body-centered cubic (bcc) metals with interstitial impurities of carbo...

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Snoek‐Type High‐Damping Alloys Realized in β‐Ti Alloys with High Oxygen Solid Solution

et al. 2006

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“…The activation enthalpy for the three processes proposed was fixed, based in values determined earlier by internal friction experiments [11][12][13] Table 2. The fact that that the peak temperatures and frequency of the processes at lower and middle temperatures do not fit the Arrhenius plots of Nb-O relaxation [3] and of the Ti-O relaxation [9] can be explained considering that, at high concentration, the substitutional Ti markedly perturbs the periodic potential of the interstitial sites so affecting the relaxation parameters of the processes [14]. …”

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confidence: 99%

“…The second process, which is dominant, is located at intermediate temperature. Because the substitutional Ti, in the Nb-Ti alloy is a strong trapping centre for oxygen atoms [9] we propose that this main process be due the stress-induced ordering of oxygen atoms around titanium atoms of metallic matrix; here labeled Ti-O process. The third relaxation at high temperature is ascribed to nitrogen (Nb-N Snoek peak), which represents the second interstitial impurity content of the alloy.…”

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confidence: 99%

“…The presence of substitutional solutes in bcc metals containing interstitial impurities modifies the stress-induced ordering of the interstitial atoms due, in general, to the formation of substitutional-interstitial complexes [9]. The purpose of this work was to investigate the influence of titanium on niobium containing oxygen in solid solution and the consequential effect on the mechanical properties of the alloy.…”

Section: Introductionmentioning

confidence: 99%

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Anelastic relaxation processes due oxygen in Nb–3.1 at.% Ti alloys

Almeida

Niemeyer

Pires

et al. 2004

Materials Science and Engineering A

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“…Na presença de uma tensão mecânica externa, estes elementos intersticiais se redistribuem nos diferentes sítios causando perda na energia elástica, difundindo-se na matriz metálica por meio de saltos entre sítios energeticamente equivalentes, causando distorções locais. A interação destes elementos intersticiais com os metais do grupo V tem sido bastante estudada por meio de medidas de atrito interno em função da temperatura [1][2][3][4] . Em metais que apresentam átomos de impurezas dissolvidos intersticialmente em sua estrutura, observam-se picos no espectro de atrito interno em função da temperatura.…”

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Espectroscopia anelástica em ligas de Nb-16% p. Ti

et al. 2003

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Átomos de oxigênio, presentes em metais com estrutura cristalina cúbica de corpo centrado, são localizados preferencialmente em sítios octaedrais. Na ausência de uma tensão mecânica externa, estes átomos são distribuídos aleatoriamente. Na presença de oscilações mecânicas, a redistribuição dos átomos nos diferentes sítios deve ocorrer pela interação com esta tensão, levando a perdas na energia elástica. Este trabalho mostra o estudo da interação de átomos de oxigênio presentes em amostras da liga Nb-16% p. Ti, utilizando um pêndulo de torção. Os resultados mostram espectros bastante complexos, que foram decompostos em seus picos constituintes, representando os processos de relaxação devido à reorientação induzida por tensão de átomos e pares de átomos de oxigênio em torno de átomos de nióbio da matriz metálica e átomos de oxigê-nio em torno de átomos de titânio (interação substitucional-intersticial). Palavras-Chave: atrito interno, difusão, intersticiais, ligas de Nb-Ti IntroduçãoÁtomos de impurezas intersticiais como oxigênio, nitrogênio, carbono e hidrogênio presentes em metais com estrutura cristalina cúbica de corpo centrado, tais como nióbio, vanádio, tântalo e suas ligas, alteram de maneira significativa as propriedades mecânicas destes metais e ligas. Em estruturas cristalinas deste tipo, tais elementos intersticiais localizam-se geralmente em sítios octaedrais. Na presença de uma tensão mecânica externa, estes elementos intersticiais se redistribuem nos diferentes sítios causando perda na energia elástica, difundindo-se na matriz metálica por meio de saltos entre sítios energeticamente equivalentes, causando distorções locais. A interação destes elementos intersticiais com os metais do grupo V tem sido bastante estudada por meio de medidas de atrito interno em função da temperatura [1][2][3][4] . Em metais que apresentam átomos de impurezas dissolvidos intersticialmente em sua estrutura, observam-se picos no espectro de atrito interno em função da temperatura.Cada espécie de átomos de soluto intersticial dá origem a um máximo no espectro da perda da energia elástica. Os princípios da natureza elástica deste fenômeno foram estabelecidos por Snoek 5 que postulou que estes átomos reorientam-se sob a ação de uma tensão externa aplicada. O pico no espectro de atrito interno em função da temperatura devido a esta reorientação ficou conhecido como Pico de Snoek.Em ligas com baixa concentração de intersticiais, o pico de Snoek é muito bem ajustado utilizando-se as equações de Debye 6 , no qual a largura a meia altura descreve a reorientação termicamente ativada de átomos isolados do soluto. Quando há agrupamentos de dois ou mais átomos intersticiais estes interagem entre si causando um alargamento da estrutura de relaxação, representado pela superposição de vários picos, um para cada tipo de interação.Este trabalho mostra o estudo da interação de átomos de oxigênio presentes numa amostra da liga Nb-16% p. Ti por meio de medidas de espectroscopia anelástica (atrito interno).

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Substitutional-interstitial interactions in niobium-titanium alloys: An internal friction study

Cited by 23 publications

References 8 publications

Snoek‐Type High‐Damping Alloys Realized in β‐Ti Alloys with High Oxygen Solid Solution

Snoek‐Type High‐Damping Alloys Realized in β‐Ti Alloys with High Oxygen Solid Solution

Anelastic relaxation processes due oxygen in Nb–3.1 at.% Ti alloys

Espectroscopia anelástica em ligas de Nb-16% p. Ti

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