Temperature Dependence Of Internal Friction Research Articles

Contributions of phase and structural transformations in multicomponent Al-Mg alloys to the linear and nonlinear mechanisms of anelasticity

The effects of the processes of severe plastic deformation (SPD), recrystallization, and precipitation of the β phase in multicomponent alloys of the Al-5Mg-Mn-Cr and Al-(4–5%)Mg-Mn-Zn-Sc systems on the mechanisms of grain-boundary relaxation and dislocation-induced microplasticity have been studied in some detail. To stabilize the ultrafine-grained structure and prevent grain growth, dispersed Al-transition-metal particles, such as Al3Zr, Al6Mn, Al7Cr, Al6(Mn,Cr), Al18Cr2Mg3 have been used. We have special interest in alloys with additions of scandium, which forms compounds of the Al3Sc type and favors the precipitation of finer particles compared to the aluminides of other transition metals. After SPD, Al-(4–5%)Mg-Mn-Zr-Sc alloys exhibit an enhanced recrystallization temperature. The general features of the dislocation and grain-boundary anelasticity that have been established for the binary Al-Mg alloys are retained; i.e., (1) the decrease in the dislocation density in the process of recrystallization of cold-worked alloys leads to the formation of a pseudo-peak in the curves of the temperature dependences of internal friction (TDIF) and to a decrease in the critical amplitude of deformation corresponding to the onset of dislocation motion in a stress field; (2) the precipitation of the β phase suppresses the grain-boundary relaxation; (3) the dissolution of the β phase, the passage of the magnesium atoms into the solid solution, and the precipitation of the β’ phase upon heating hinder the motion of dislocations; (4) the coarsening of the highly dispersed particles containing Zr and Sc increases the dislocation mobility. The grain-boundary relaxation and dislocation-impurity interaction and their temperature dependences, as well as processes of the additional alloying of the binary alloys by Mn, Cr, Zr, and Sc, have been estimated quantitatively.

Contribution of phase and structural transformations to linear and nonlinear mechanisms of anelasticity in binary Al-Mg alloys

Effects of the processes of the recrystallization and precipitation of the β phase in Al-(0.3–12%)% Mg alloys on the mechanisms of grain-boundary relaxation and dislocation-induced microplasticity have been studied in some detail. The decrease in the dislocation density due to the process of recrystallization of cold-worked alloys leads to the formation of a pseudopeak in the curves of the temperature dependence of internal friction and to a decrease in the critical amplitude of deformation necessary to initiate dislocation motion in a stress field. The precipitation of the β phase in the structure suppresses the mechanism of grain-boundary relaxation; the dissolution of the β phase, which leads to the formation of impurity atmospheres, then to the passage of magnesium atoms into the solid solution, impedes dislocation motion. Depending on the total content of Mg in the alloy, the dislocation mobility upon the measurements of amplitude dependences of internal friction can be described in terms of either breakaway or friction models. The characteristics of grain-boundary relaxation and dislocation-impurity interaction and of their temperature dependences have been estimated quantitatively.

Internal Friction in the Ferroelectric – Ferromagnetic Composites

Abstract In the work, temperature Q-1(T) and amplitude Q-1(") dependences of internal friction for ferroelectric - ferromagnetic composites on the base of the PZT and ferrite were determined. The temperature dependences of internal friction Q-1 reveal the peak in the range of high temperatures. We have investigated the peak associated with the viscous-elastic mobility of ferroelectric domain walls. The internal friction due to the viscous-elastic mobility of ferroelectric domain walls was calculated and compared with the experimental data in the reference to the Wang’s theory. Based on internal friction measurements and theoretical considerations, the peak was described. Additionally the amplitude (isothermal) Q-1(") dependences for the composites were made. This allowed for the interpretation of the maximum observed on the temperature dependences of the internal friction Q-1(T).

Mechanisms of linear anelasticity in Fe-M and Fe-Al-M (M = Ga, Ge) alloys

Linear anelastic effects in binary and ternary alloys of iron with 13 and 17 at % Ga, 12 at % Ge, and 4–8 at % Al (Fe-13Ga, Fe-17Ga, Fe-12Ge, Fe-8Al-3Ga, Fe-8Al-4Ge, and Fe-4Al-8Ge) have been investigated. In all of these alloys, thermally activated effects of linear anelasticity have been found and identified that are caused by point defects in interstitial (Snoek-type relaxation) and substitutional (Zener relaxation) solid solutions, as well as by dislocations (Hasiguti effect), and by grain boundaries. The effects of the alloy composition on the activation parameters of the above-mentioned relaxation mechanisms have been determined. In addition, frequency-independent effects related to processes of structural rearrangement, such as ordering and disordering of the alloys have been revealed due to the specific features in the curves of the temperature dependences of internal friction for almost all compositions.

Experimental verification of segregation of carbon and precipitation of carbides due to deep cryogenic treatment for tool steel by internal friction method

This work presents an internal frictional behavior of cold work tool steel subjected to different heat treatment schedules to get insight related to segregation of carbon and refinement of carbide particles due to deep cryogenic treatment. The temperature dependence of internal friction was used to describe the variation of carbon concentration in solid solution of the martensite matrix in successive tempering steps. The results indicate that the carbon atoms segregated to nearby defects forming atomic clusters producing strong interactions, including interstitial carbon atoms themselves and between the interstitial carbon atoms with time-dependent strain field of dislocations because of lattice shrinking and thermodynamic instability of martensite during the deep cryogenic treatment. The clusters act as and grow into nuclei for the formation of fine carbide particle on subsequent tempering that was verified by analyses of TEM micrographs.

Internal Friction during Reverse Martensitic Transformation in Mn-Cu Alloy with 45 % Mn

The temperature and amplitude dependence of internal friction fcc Mn45Cu55 alloy aged at 400 °C were studied. Two low-temperature internal friction peak observed in the quenched state. Physical mechanism of the peaks was determined by the effect of frequency and strain amplitude on the temperature dependence of internal friction. The influence of the heat treatment to the internal friction of the investigated alloy was shown.

Effect of heat treatment on internal friction in ECAP processed commercial pure Mg

Fine-grained commercial pure Mg was prepared by equal channel angular pressing. Heat treatments were carried out on ECAP processed samples to modify the microstructures, such as the density of dislocation, grain size and grain boundary, and their effects on internal friction at room and elevated temperatures have been studied in detail by dynamic mechanical analyzer (DMA). The ECAP processed pure Mg shows a high value of strain independence of internal friction, which is reduced after heat treatment due to the decrease of mobile dislocations, while the strain dependent part obviously increases owing to the larger grain size. Three internal friction peaks are observed during the measurements of temperature dependence of internal friction. The low temperature peak around 100–200°C is considered to be caused by thermally activated grain boundary relaxation, and it is obviously broadened compared with a Debye peak for a single relaxation time. The changes of activation energy and relaxation time distribution of this peak with an increase in grain size were also studied. The other two peaks at the temperature range of 200–350°C are frequency independent and associated with some irreversible structural transformation, they are considered to be related to the recrystallization.

On combining high damping capacity and high strength in nanocrystalline materials

Nanocrystalline materials obtained by the method of severe plastic deformation are studied. Successive recrystallization annealing operations are used to form different structural states in specimens. Tensile tests and measurements are performed to determine the amplitude and temperature dependences of internal friction in specimens of copper and stainless steel.

Improved mechanical property and internal friction of pure Mg processed by ECAP

Equal channel angular pressing was performed on the extruded pure Mg. The elongation to failure of the ECAPed pure Mg is enhanced to 27% without sacrificing the strength, which is mainly resulted from both the effective refinement of grain size and the weakening of the basal plane texture. The internal friction mechanisms of magnesium at room and elevated temperature were studied by dynamic mechanical analyzer (DMA). The strain independent internal friction is increased after ECAP processing, while the strain dependent part is obviously decreased. Three internal friction peaks were observed in the temperature dependent internal friction curves. The activation energy is 105kJ/mol for P1 peak, which may be related to the basal dislocation glide controlled by climb of jogs and diffusion of vacancies along dislocations. The activation energy of P2 peak is in the range from 95 to 181kJ/mol, and this obviously broadened peak is associated with grain boundary relaxation. The P3 peak is related to recrystallization.

Internal friction in (Fe80Ga20)99.95(NbC)0.05 alloy at elevated temperatures

The temperature and frequency dependent internal friction of a rolled (Fe80Ga20)99.95(NbC)0.05 alloy has been investigated using computer-controlled automatic inverted torsion pendulum instruments. The measurements were carried out in forced vibration mode from room temperature up to 973 K with frequency varying between 0.5 Hz and 11 Hz. Results obtained by standard methods of XRD, SEM and DSC show that the main phases in the specimen structure is the disorder A2 phase (random solid solution) and the NbC phase. Two internal friction peaks are observed in the temperature range from room temperature to 973 K. The low-temperature peak at about 423 K occurs only at high quenching temperature and may be a complex effect consisting of Snoek-type relaxation and vacancies/ordering effect. A pronounced thermally activated relaxation peak (P1) at about 750 K observed in all samples with activation energy of 2.21–2.84 eV and relaxation time of 1.71 × 10−20–8.79 × 10−17 s is classified as the Zener peak. The high damping background above P1 is caused by the interaction between NbC precipitates and Ga solution particles at high temperature. The high temperature peak (P2) at about 873 K is only observed in samples water quenched below 1173 K. The P2 peak disappears if the samples are water quenched from temperature above 1373 K. The P2 peak height is strongly dependent on annealing temperature and the damping background decreases quickly with increasing temperature. According to activation energy, the P2 peak is most probably originating by grain boundary relaxation. In particular, the particles on the grain boundaries lead to grain boundary relaxation.

Mechanical Spectroscopic Study of Equal-Channel Angular Pressed Al-Ni Eutectic Alloy

In this study, temperature dependence of internal friction, tand, of ECAPed Al-Ni eutectic alloy was measured using a dynamic mechanical analysis (DMA) to discuss the recrystallization behavior of the alloy. The temperature dependence of internal friction of 8 passed samples shows a large peak at around 200 °C on heating, while this peak disappears on the subsequent cooling stage. Moreover, smaller peak was observed for 2 passed samples. Therefore, it can be concluded that the origin of the peak comes from the recrystallization of a-Al.

Temperature-dependent internal friction of clay in a cylindrical heat source problem

The effect of the temperature dependence of the internal friction angle is studied in a boundary value problem simulating the impact of a cylindrical heat source on the soil mass in which it is embedded. This follows a previous study which shows that such temperature dependence may substantially affect the interpretation of thermal failure in laboratory experiments. Even if the thermal increase of the internal friction is quite modest (less than 20% in terms of the critical state parameter, M), it affects quite significantly the effective stress path near the heat source. The effective stress path approaches the yield locus and the critical state at significantly higher principal stress difference values for the variable internal friction than for the M = const case. The ‘mean effective stress distance from the critical state' is substantially reduced during heating, which in the case of small perturbations of any parameter may lead to potentially unstable or statically inadmissible behaviour. The solutions obtained allow one to identify zones of influence around the heat source of several variables of interest. The two fields most affected by the thermal sensitivity of M are that of the axial stress, dropping significantly near the heat source, and that of the appearance of the thermoplastic strain. Both zones of influence are reduced in size by almost half when the friction angle is increased by 20% over 70°. The presented results may be of relevance to the design of prototype in situ installations and their monitoring, and eventually of actual facilities for nuclear waste disposal.

Internal friction, dilatometric and calorimetric study of anelasticity in Fe–13 at.% Ga and Fe–8 at.% Al–3 at.% Ga alloys

This paper investigates the structural transitions associated with different cooling rates from a high temperature disordered state and the effect of substitution of Ga atoms by Al atoms in Fe–Ga binary alloys on the ordering processes. Two iron-based low carbon (about 0.04 at.% C) alloys Fe–13 at.% Ga and Fe–8 at.% Al–3 at.% Ga are studied. Internal friction, dilatometric and calorimetric tests are carried out to check ordering in these alloys and contribution of structural defects to relaxation spectrum. Several thermally activated internal friction peaks have been observed and their activation parameters evaluated by means of temperature and frequency dependent internal friction tests using forced vibration. For most of these peaks physical mechanisms are proposed. Apart from these thermally activated relaxation peaks, a structural, frequency independent relaxation takes place at 250–300 °C. Dilatometric and DSC curves show the appearance of a contraction effect in the same temperature range. This effect was studied in alloys cooled down with different cooling rates. We believe that the frequency independent internal friction peak (denoted as the P3 peak in this paper) and peaks at dilatometric and DSC curves are controlled by the same structural mechanism and therefore the activation energy for this anelastic mechanism is derived from DSC data.

Temperature dependence of internal friction in enzyme reactions

Our aim was to elucidate the physical background of internal friction of enzyme reactions by investigating the temperature dependence of internal viscosity. By rapid transient kinetic methods, we directly measured the rate constant of trypsin 4 activation, which is an interdomain conformational rearrangement, as a function of temperature and solvent viscosity. We found that the apparent internal viscosity shows an Arrhenius-like temperature dependence, which can be characterized by the activation energy of internal friction. Glycine and alanine mutations were introduced at a single position of the hinge of the interdomain region to evaluate how the flexibility of the hinge affects internal friction. We found that the apparent activation energies of the conformational change and the internal friction are interconvertible parameters depending on the protein flexibility. The more flexible a protein was, the greater proportion of the total activation energy of the reaction was observed as the apparent activation energy of internal friction. Based on the coupling of the internal and external movements of the protein during its conformational change, we constructed a model that quantitatively relates activation energy, internal friction, and protein flexibility.

Thermally Activated Relaxation and Hysteretic Internal Friction in Ultrafine Grained Copper

Temperature and amplitude dependent internal friction (TDIF and ADIF) in ultrafine-grained copper (99.95% Cu) specimens processed by equal channel angular extrusion by route BC in 1, 4, and 8 passes and then subjected to annealing is investigated by means of dynamical mechanical analyzer DMA Q800 in the temperature range from -100 to 550 °C, amplitude range from 10-6 to 10-3, and frequency range from 0.05 to 100 Hz. Two IF peaks were registered and explained by structural relaxation due to the recrystallisation process and by thermally activated grain boundary relaxation with broad distribution of relaxation times. Increase in amplitude dependent damping in ultrafine-grained copper is due to dislocation but not grain boundary contribution.

Mechanisms of anelasticity in Fe–13Ga alloy

Thermally activated frequency and temperature dependent anelastic effects in Fe–Ga alloys are practically not studied as yet in spite of the capacity of these alloys to dissipate energy of mechanical vibrations due to magneto-mechanical damping. In this paper we have studied iron-based composition with 13 at.% Ga. Several thermally activated peaks have been discovered and their activation parameters are evaluated by means of temperature and frequency dependent internal friction tests using free-decay and forced vibrations. Physical mechanisms are proposed for most of these peaks. In addition to thermally activated relaxation peaks, an irreversible internal friction peak is recorded due to structural transformation around 200 °C. This peak is frequency independent and is accompanied by inverted modulus behaviour. High damping capacity of Fe–13Ga alloy is confirmed.

Mechanical Spectroscopy of Ultrafine Grained Copper

Temperature and amplitude dependent internal friction (TDIF and ADIF) in ultrafine-grained copper (99.95% Cu) processed by 1, 4, or 8 passes of equal channel angular pressing (route BC) and then subjected to annealing was investigated by means of mechanical spectroscopy. A dynamical mechanical analyzer DMA Q800 was used. The tests covered the temperature range from -100 to 550 °C, the strain amplitude range from 10-6 to 10-3, and the frequency range from 0.05 to 100 Hz. Two internal friction peaks were observed. They were explained by structural relaxation due to the recrystallisation process and by thermally activated grain boundary relaxation with a broad distribution of relaxation times. Increased amplitude dependent damping in ultrafine-grained copper is believed to be associated with a dislocation mechanism, rather than a grain boundary mechanism.

Grain-boundary relaxation in copper before and after equal-channel angular pressing and recrystallization

Temperature-dependent internal friction and modulus of elasticity have been studied in samples of pure copper (99.95%) subjected to deformation by equal-channel angular pressing using 1, 4, and 8 passes by the route B C. The influence of deformation and subsequent recrystallization on the parameters of the internal-friction peaks caused by grain-boundary relaxation and recrystallization of severely deformed copper has been determined. Quantitative estimates of the activation parameters of grain-boundary relaxation have been obtained and the limits of its manifestation have been revealed.

The mechanism investigation of deep cryogenic treatment on high alloy martensitic steel by low frequency internal friction

Effects of deep cryogenic treatment (DCT) on the internal friction (IF) in high-carbon alloy steel are investigated. The temperature dependent internal friction (TDIF) of the quenched and DCT treated samples were measured in an inversed torsion pendulum with high vacuum by using free decay method. The TDIF of quenched sample is decomposed into four peaks: P1 at 342 K, P2 at 443 K, P3 at 492 K and P4 at 580 K. Peak P1 is attributed to the relaxation associated with the reorientation of interstitial solute atoms in metals under the application of oscillatory stress. Peak P2 is related to the carbides precipitation. Peak P3 is considered as the Snoek-Kê-Köster (SKK) peak, which is caused by both dislocations interaction and interstitial atoms decorating these dislocations. Peak P4 is attributed to retained austenite transformation basing on the peak disappearing while the samples carried out DCT treating.

Effect of alloying with Mn and Co on the temperature dependence of internal friction in Fe-Ni-C invar alloys

Temperature dependences of internal friction (TDIF) have been studied by the method of resonance bending vibrations in a kilohertz frequency range in the temperature range from 100 to 900 K in fcc Fe-Ni-X and Fe-Ni-X-C (X = Mn, Co) alloys with a Ni content of about 30 wt %. To produce a single-phase austenitic structure, the alloys were homogenized at 1373 K in vacuum and rapidly cooled in oil. At temperatures of 550–587 K, above the Curie temperature of the alloys, in the TDIF curves there is observed a carbon relaxation peak of internal friction. It has been demonstrated that in the alloys studied the temperature of the peak Tmax at vibration frequencies of 1.5–2 kHz is more than 100 K higher than the Curie point TC and that the alloying elements Mn and Co increase the difference between Tmax and TC. The activation energy calculated within the framework of the Wert-Marx model is equal to 1.1 eV. It has been found out that the alloying of Fe-Ni-C with Mn induces a certain decrease in the temperature and intensity of the carbon peak, while addition of Co, on the contrary, leads to an increase in the peak temperature and intensity of damhing of elastic vibrations. The causes of such effect have been considered.