High Temperature Internal Friction and Dislocation Motion in Poly and Single Crystals of F.C.C. Metals

Rivière, A.; Amirault, J. P.; Woirgard, J.

doi:10.1051/jphyscol:1981565

Cited by 14 publications

(13 citation statements)

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“…On referring to peaks exhibited by polycrystalline and monocrystalline aluminum, for example Riviere et al [47] gave a table where three peaks were summarized. For the values Tp/Tm (at 1 Hz) of 0.43, 0.65 and 0.73 they measured the ratios M-//AHsD = = 0.64, 0.69 and 0.66, respectively.…”

Section: "7mentioning

confidence: 99%

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Present state of the controversy about the grain boundary relaxation

Povolo

Molinas

1992

Il Nuovo Cimento D

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Summary. --An analysis of the internal friction produced by grain boundary relaxation in metals and alloys and ceramics is presented. The different interpretations given in the literature to relaxation phenomena occurring at temperatures above about half the melting point which include the influence of grain boundaries and their interaction with solutes and precipitates are discussed in detail. A complete set of the experimental data disposable in this field since 1972 up today is rewiewed. Finally, some recent experiments are discussed and new ones are suggested. They might solve the actual controversy about the real origin of the relaxation phenomena observed.PACS 62.40 -Anelasticity, internal friction, and mechanical resonances.

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Section: "7mentioning

confidence: 99%

“…Successive works carried out by Poiter's group[ll, 16,47] showed that the high-temperature damping spectra in pure f.c.c, metals can be analysed by means of two to four peaks, located between 0.3 Tm and 0.7 Tm not only in polycrystals but also in single crystals.…”

Section: "7mentioning

confidence: 99%

Present state of the controversy about the grain boundary relaxation

Povolo

Molinas

1992

Il Nuovo Cimento D

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“…In many metallic polycrystals, a relaxation peak is observed at about half the melting temperature [1][2][3], which has been either attributed to GB sliding [4] in agreement with the Zener model [5] or to dislocation mechanisms [6,7]. Observations on Al bi-crystals containing a single GB showed a relaxation peak closely related to the GB and dependent on the misorientation angle [8].…”

Section: Introductionmentioning

confidence: 87%

Grain Boundary Relaxation in Bi-Crystals: Mechanical Spectroscopy and Molecular Dynamics Simulations

Maier¹,

Mari²,

Tkalcec³

et al. 2015

Archives of Metallurgy and Materials

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Different Au-Ag-Cu samples have been studied by mechanical spectroscopy. Both polycrystals and bi-crystals show a relaxation peak at 800 K, accompanied by an elastic modulus change. Since this peak is absent in single crystals it is related to the presence of grain boundaries. Molecular dynamics simulations reveal two microscopic mechanisms, when a shear stress is applied onto a Σ5 grain boundary: at 700 K, the boundary migrates perpendicularly to the boundary plane under an external stress. At 1000 K, only sliding at the boundary is observed. These two mechanisms acting in different temperature intervals are used to model the mechanic response of a polycrystal under an applied stress. The models yield expressions for the relaxation strength ∆ and for the relaxation time τ as a function of the grain size. A comparison with the mechanical spectroscopy measurements of polycrystals and the bi-crystals show that the grain boundary sliding model reproduces correctly the characteristics of the grain boundary peak.Keywords: Internal friction grain boundaries, gold alloy, molecular dynamics Różne próbki ze stopów Au-Ag-Cu badano metodą spektroskopii mechanicznej. Zarówno w polikryształach, jak i bikryształach występuje pik relaksacyjny w temperaturze 800 K, któremu towarzyszy zmiana modułu sprężystości. Ponieważ pik ten nie występuje w monokryształach to jego występowanie wiązane jest z obecnością granic ziaren. Symulacje dynamiki molekularnej ujawniają dwa mikroskopowe mechanizmy, gdy naprężenie ścinające jest przyłożone do granicy ziarna Σ5: w temperaturze 700 K, granica przemieszcza się prostopadle do płaszczyzny granicznej pod wpływem zewnętrznego naprężenia. W 1000 K, obserwuje się tylko poślizg po granicy. Te dwa mechanizmy działające w różnych zakresach temperatur są używane do modelowania mechanicznej reakcji polikryształu na przyłożone naprężenie. Modele podają wyrażenie na stopień relaksacji ∆ i czas relaksacji τ w funkcji wielkości ziaren. Porównanie z wynikami badań polikryształów i bikryształów uzyskanych metodą spektroskopii mechanicznej pokazuje, że model poślizgu granicy ziarna poprawnie odtwarza charakterystykę piku pochodzącego od granic ziaren.

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“…In the case of polycrystals of A1 4N and AI 5N with bamboo microstructure, these authors observe a relaxation also at 640K when the sample has been deformed 3% and annealed at 830K. This relaxation is dependent on the oscillating amplitude [7] and dissapears by tensile deformation [8]. Using another kind of internal friction measurements, stabilizing the temperature 4 hours before each measurement, Rivi2re et a1 [9-1 l] observe three relaxations PI, P2 and P3 that are amplitude independent and besides P2 and P3 do not disappear even after annealing at 800K.…”

Section: Introductionmentioning

confidence: 99%

“…In Fig.4 we plot the internal friction spectra and modulus variation curves corresponding to the oscillating amplitudes of 4,8, Fig.4, it becomes evident that the P3 peak shows a strong dependence on the oscillating amplitude. The previous results allows to conclude that the P3 relaxation is due to some mechanism of dislocation mobility and the associated modulus defect curves (in Fig.4) suggest that this relaxation could be linked to the same dislocations responsible for the P2 peak.…”

Section: Temp (K)mentioning

confidence: 99%

Relaxation Mechanisms in High Purity 99.999% Aluminium at Medium Temperatures

1996

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Abstract. In this work we have studicd the microstructural conditions for the appearance of the P3 relaxation at about 650K in 99.999% Aluminium. The experimental behaviour of the P3 peak allows us to conclude that it is linked to a process of dislocation mobility. l. INTRODUCTIONThe internal friction (IF) spectra in A1 5N single crystals was studied by Woirgard et al. [1,2] between 300K and 700K and decomposed in a high temperature background plus three relaxation peaks named Pi, P2 and Pg. These relaxations appear also in bicrystals and an annealing at 673K increases the P2 and P3 relaxations. In polycrystals Woirgard et al. [1,2] observe so high the P2 relaxation that the P1 and P3 relaxations are hidden. These results were confirmed by Bonetti et al. [3], who observe in A1 4N single crystals slightly deformed by flexion three relaxations K1, K2 and H that increase with the deformation degree and do not disappear even after annealing at 813K during 12 hours. These relaxations appear also in polycrystals after primary recrystallization, being much more strength than in single crystals [3,4]. On the contrary, KC et al. [S] do not observe any relaxation between 450K and 700K in A1 4N and A1 5N single crystals grown by zone melting. Nevertheless they observe a peak around 640K (named P365) in similar single crystals grown by dynamic annealing [5-71, but this peak disappears after a 5% creep deformation at the temperature of the peak maximum, or after a 5% tensile deformation at room temperature followed by a 2h annealing at 87313 [7]. In the case of polycrystals of A1 4N and AI 5N with bamboo microstructure, these authors observe a relaxation also at 640K when the sample has been deformed 3% and annealed at 830K. This relaxation is dependent on the oscillating amplitude [7] and dissapears by tensile deformation [8]. Using another kind of internal friction measurements, stabilizing the temperature 4 hours before each measurement, Rivi2re et a1 [9-1 l] observe three relaxations PI, P2 and P3 that are amplitude independent and besides P2 and P3 do not disappear even after annealing at 800K.A comparative and exhaustive study of the relaxations observed in the literature in A16N, AlSN and A14N at medium and high temperatures has been acomplished by N6 [12]. This study allows her to conclude that the high temperature component of the KC peak, as well as the P365, P3 and H peaks are the same relaxation, that in the present work will be named as P3 peak.The aim of this work is to contribute with some suplementary results about the P3 peak in order to understand its behaviour and to clarify the microscopic mechanism responsible for this relaxation. EXPERIMENTAL CONDITIONSIn the present work we used 99.999% Aluminium (5N) "super raffinal" AIAG. The 5N A1 supplied in l0mm plates was rolled until it was l.lmm thick and annealed under primary vacuum for l h at 500K in order to recrystallize the samples, that were subsequently aged for a long time at room temperature. In this condition the samples show a mixed microstructure ...

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High Temperature Internal Friction and Dislocation Motion in Poly and Single Crystals of F.C.C. Metals

Abstract: High temperature i n t e r n a l friction experiments were performed on different poly a n d single c r y s t a l s of four (Al, Ag, Cu, N i) FCC metals in the Hz frequency range. Damping spectra exhibits relaxation peaks even for vibration

Cited by 14 publications

References 2 publications

Present state of the controversy about the grain boundary relaxation

Present state of the controversy about the grain boundary relaxation

Grain Boundary Relaxation in Bi-Crystals: Mechanical Spectroscopy and Molecular Dynamics Simulations

Relaxation Mechanisms in High Purity 99.999% Aluminium at Medium Temperatures

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