Internal Friction Peak Height Research Articles

Low-frequency internal friction in ferroelectric Ba0.8Sr0.2TiO3 and Ba0.8Sr0.2TiO3 + 0.2 mass. % La ceramics

The temperature dependences of internal friction and Young’s modulus in ferroelectric Ba0.8Sr0.2TiO3 ceramics under bending oscillations were investigated at frequencies of the several hertz. The effect of the heating rate and the frequency of oscillations on the internal friction peak height near the Curie temperature was studied. The fluctuation model of low-frequency internal friction is used to explain the obtained dependences and to estimate the nuclei volume of a new phase arising at a phase transition. After a dc electric field switched on in the ferroelectric phase, the time decrease of internal friction was observed, which had an exponential form. The addition of 0.2 mass. % La in Ba0.8Sr0.2TiO3 led both to an increase in the internal friction level in the ferroelectric phase and to a decrease in the internal friction maximum near the Curie temperature. In the first case, this was explained by a decrease in the interaction energy of charged point defects with ferroelectric domain walls, and in the second case, by the pinning of domain walls by lanthanum ions.

Effects of Parent Phase Aging and Nb Element on the Microstructure, Martensitic Transformation, and Damping Behaviors of a Cu–Al–Mn Shape Memory Alloy

It is recognized that both parent phase aging and element addition can dramatically enhance the comprehensive properties of Cu‐based shape memory alloys (SMAs). However, further in‐depth studies are still needed to clarify the detailed laws and mechanisms. Herein, the effects of parent phase aging and Nb element on the microstructure, martensitic transformation (MT), and damping behaviors of a Cu–Al–Mn SMA are systematically studied. It is found that both the damping at low temperatures and the height of internal friction peak arising from the reverse MT of the Cu–Al–Mn SMA can be improved by the parent phase aging due to the increase in interfacial mobility. When the aging temperature reaches 600 °C, the best damping can be obtained. Nb forms AlNb3 phase in the Cu–Al–Mn matrix. Due to the pinning effect of the AlNb3 phase on grain boundaries, the grains of the Cu–Al–Mn SMA can be remarkably refined. With the increase in Nb content, the damping of the 600 °C aged Cu–Al–Mn SMA increases first and then decreases. The associated mechanisms are discussed. This work aims to provide theoretical basis and technical support for the improvement of damping property of Cu‐based SMAs.

Snoek-type relaxation caused by interstitial atoms in sintered <i>β</i>-type Ti-Nb alloy

<sec> The <i>β</i>-type Ti-Nb alloys are potential shape memory and superelasticity materials. The interstitial atoms in the alloys have important effect on their physical and mechanical properties. For the interstitial atoms, the internal friction technique can be used to detect their distributions and status in the alloys. The influences of chemical compositions and heat treatments on the microstructures of the containing-oxygen Ti-Nb alloys are given, and a clear understanding and the relaxational mechanism of the internal friction peak correlated with oxygen are also clearly discussed by investigating the internal friction behavior of the alloys and the detecting their microstructures. </sec><sec> The Ti-Nb alloys with different Nb content values are prepared by powder metallurgy. The internal friction behaviors of Ti-Nb alloys with different Nb content values and heat treatments are investigated by using dynamic mechanical analysis (dynamic mechanical analyzer, DMA) Q800 from TA Instruments in single cantilever mode under different testing parameters and conditions from room temperature to 350 ℃. The X-ray diffraction experiments are also carried out in order to detect the differences among the microstructures of the specimens with different heat treatments for the Ti-35.4Nb alloy. It is shown that relaxational internal friction peaks are found on the internal friction temperature dependent curves of the sintered and water-quenched alloys. The internal friction peak is correlated with Nb content. The peak does not appear in the sintered Ti-Nb alloys with low Nb content. The maximum of the internal friction peak appears in the quenched alloy with about 35% Nb. The internal friction peak height increases monotonically with Nb content increasing in the present testing composition range for the sintered alloys. The relaxation parameters are the activation energy <i>H<sub>wq</sub></i> = (1.67 ± 0.1) eV and the preexponential factor <i>τ</i><sub>o<i>wq</i></sub> = 1.1 × 10<sup>－17 ± 1</sup> s for the quenched Ti-35.4Nb alloy . In addition, the peak height also depends on heat treatment. The water-quenched Ti-35.4Nb alloy has much higher internal friction peak than the as-sintered alloy with identical compositions. The internal friction peak height is also correlated with the quenching temperature. It is found that the peak is linked to the <i>β</i> phase of Ti-Nb alloys and that the peak height is determined by the stability and amount of the <i>β</i> phase from their microstructures. When the stability of the <i>β</i> phase decreases, the peak height increases, and the increase in the amount of <i>β</i> phase results in the increase of the peak height. The <i>β</i> phase in the quenched Ti-35.4Nb specimen is metastable <i>β</i> phase (<i>β</i><sub>M</sub>), which can be transformed into the stable <i>α</i> and <i>β</i><sub>S</sub> by ageing. The <i>β</i> phase in as-sintered specimen is the stable <i>β</i> phase (<i>β</i><sub>S</sub>). The modifications of microstructures of the specimens with different heat treatments result in the difference in peak height between the water-quenched and as-sintered Ti-35.4Nb specimens. That the peak height presents a maximum in the vicinity of 35 wt.% Nb for the quenched alloys results from the variation of the stability and amount of <i>β</i><sub>M</sub> with Nb content. That the height of the peak increases monotonically with Nb content increasing in as-sintered alloys is attributed to the increase of the amount of <i>β</i><sub>S</sub>. It is suggested that the internal friction peak is related to oxygen jump in lattice or the interaction between the oxygen-substitute atoms in <i>β</i><sub>M</sub> phase for the water-quenched alloys and those in <i>β</i><sub>S</sub> phase for the as-sintered alloys.</sec>

Comment on “Experimental verification of segregation of carbon and precipitation of carbides due to deep cryogenic treatment for tool steel by internal friction method” by Li et al. [Mater. Sci. Eng. A 575 (2013) 51–60

We want to make three comments to the article by Li et al. [1]. The first one is the interpretation of the internal friction peak at 382K, which they attributed to the Snoek effect, but other authors suggest that this effect is not possible in martensite [2–4]. The second one is the interpretation of the changes in the height of internal friction peak at 580K. They attributed it to the segregation of carbon, but we believe that it can also be associated to the increasing dislocation density. Finally, we want to indicate that the increasing of dislocation density can also be a mean reason of the enhancement of wear resistance by deep cryogenic treatment as well as segregation of carbon and the transformation of austenite into martensite.

Internal friction associated with the premartensitic transformation and twin boundary motion of Ni50+xMn25−xGa25 (x = 0−2) alloys

The internal friction (IF) during the martensitic transformation (MT) has been extensively studied in NiMnGa alloys. In this paper, temperature dependence of the IF associated with the premartensitic transformation (PMT) and twin boundary motion (TBM) was investigated in Ni50+xMn25−xGa25 (x = 0−2) alloys. Both the composition and frequency had no obvious effect on the IF peak position of the PMT and TBM. With increasing frequency from 0.1 Hz to 5 Hz, the IF peak height corresponding to the TBM was significantly decreased, but was kept constant during the PMT. The observed phenomena were discussed in terms of the different microscopic mechanisms of the TBM and PMT.

Phase transformation in oil-quenched Ni–21.2Al–20Fe alloy

The internal friction ( Q −1) and the relative dynamic modulus (RDM) of the oil-quenched Ni–21.2Al–20Fe alloy were measured using a multifunctional internal friction apparatus by forced-vibration methods from room temperature to 200 °C. An internal friction peak is represented on the internal friction-temperature curve at about 113 °C during heating and the peak is shifted to about 38 °C during cooling for the oil-quenched alloy. The peak temperature does not change for different vibration frequencies during both heating and cooling, and therefore the peak is non-relaxational. It has been shown that the peak-heights decrease with increasing f and decreasing heating rate ( T ˙ ) and are linearly and directly proportional to T ˙ / f . DSC measurements show that there is an endothermal peak at 107 °C and an exothermal peak at 42 °C on the heating curve and cooling curve, respectively. Both temperature values are similar to those of the internal friction measurements during heating and cooling, respectively. XRD results show that the oil-quenched Ni–21.2Al–20Fe alloy possesses martensitic structures (L1 0) in addition to Ni 3Al and Ni 5Al 3. It can be deduced that the internal friction peak during heating is resulted from reverse martensitic transformation of L1 0 → γ and originated from martensitic transformation of γ → L1 0 during subsequent cooling. The internal friction peak height increases when Fe content is raised.

Frequency Dependence of the Internal Friction for Ti50Ni48.5Fe1.5 Shape Memory Alloy

The objective of this work is to investigate the influence of measuring frequency on the internal friction of Ti50Ni48.5Fe1.5 shape memory alloy. The DSC, DC electrical resistivity and internal friction measurements were employed to characterize the sample in this study. Comparing the DSC result, the two internal friction peaks were confirmed which are corresponding to the R-phase transformation and martensitic transformation of Ti50Ni48.5Fe1.5 alloy during the cooling process, respectively. The height of internal friction peak corresponding to martensitic transformation increased with decreasing of measuring frequency. But, the height of the internal friction peak corresponding to R-phase transformation exhibited little measuring frequency dependence. Meanwhile, the value of the relative modulus peaks of the specimen increased with measuring frequency increasing. Furthermore, there was an interesting phenomenon that the martensitic transformation finish temperature shifted to higher temperature side with increasing of measuring frequency. It could be associated with the variation of applied vibration energy.

EFFECT OF PRE-DEFORMATION ON DAMPING CAPACITY OF TINI/NBTI COMPOSITE

The present work aims to investigate the internal friction and effect of pre-deformation on damping capacity of Nb 60 Ti 25 Ni 15 alloy, which could be considered as TiNi / NbTi metal matrix composite. The internal friction results showed that this composite possesses excellent damping behavior, which is associated with the movement of a set of abundant interfaces, such as those between the TiNi and NbTi phases, those between martensitic variants and those between martensite and parent phase. Meanwhile, the peak temperature and the width of the internal peak increased with increasing of prestrain level. It appears to be due to the release of the stored elastic strain energy, or the pinning effect by the deformed structures. Furthermore, the height of internal friction peak decreased as the prestrain level increased.

Influence of aging on damping behavior of TiNi/TiNi alloys synthesized by explosive welding

The influence of aging time, measuring frequency and strain amplitude on the internal friction of TiNi 51/TiNi 50.2 sandwich composite was investigated. The DSC and internal friction measurements were employed to characterize the sample. The two internal friction peaks of the specimen were confirmed corresponding to the reverse transformation of TiNi 51 and TiNi 50.2 component, respectively. The internal friction as a function of the temperature at different measuring frequencies was presented and it was found that the height of both internal friction peaks increased with decreasing frequency; however, the increase corresponding to TiNi 50.2 component was larger than that of TiNi 51 component. Furthermore, the internal friction of the TiNi/TiNi composite alloy decreased with increasing the measuring strain amplitude. The height of internal friction peak of TiNi 51 component increased with increasing the aging time, whereas that of the TiNi 50.2 component did not change significantly. The increase in internal friction of TiNi 51 appeared to be associated with the formation and growth of precipitate during the aging process.

Mechanical resonance of the austenite/martensite interface and the pinning of the martensitic microstructures by dislocations inCu74.08Al23.13Be2.79

A single crystal of Cu74.08Al23.13Be2.79 undergoes a martensitic phase transition at 246 and 232 K under heating and cooling, respectively. The phase fronts between the austenite and martensite regions of the sample are weakly mobile with a power-law resonance under external stress fields. Surprisingly, the martensite phase is elastically much harder than the austenite phase showing that interfaces between various crystallographic variants are strongly pinned and cannot be moved by external stress while the phase boundary between the austenite and martensite regions in the sample remains mobile. This unusual behavior was studied by dynamical mechanical analysis (DMA) and resonant ultrasound spectroscopy. The remnant strain, storage modulus, and internal friction were recorded simultaneously for different applied forces in DMA. With increasing forces, the remnant strain increases monotonously while the internal friction peak height shows a minimum at 300 mN. Transmission electron microscopy shows that the pinning is generated by dislocations which are inherited from the austenite phase.

Size-Dependent Melting Behaviour of Nanometre-Sized Pb ParticlesStudied by Dynamic Mechanical Analysis

Nanometre-sized (hereafter nano-) Pb particles embedded in an Almatrix are prepared by ball milling. It is found that the size ofnano-Pb particles was decreased with increasing milling time. Themelting behaviour of nano-Pb particles embedded in the Al matrix isstudied by means of dynamic mechanical analysis, and a single internalfriction peak in the vicinity of Pb melting temperature is observed.The onset temperature of the peak moves to lower temperature with thedecrease of particles size and the internal friction peak height isincreased, which indicates a size-dependent melting behaviour ofnano-Pb particles. It is suggested that the size-dependent meltingbehaviour is associated with surface melting.

二相ステンレス鋼とその溶接金属の水素による内部摩擦におよぼす組織の影響

We evaluated not only total hydrogen content in duplex stainless steel and its weld metal but also hydrogen content in austenite by using internal friction measurement. The internal friction measurement was conducted over the temperature range from liquid nitrogen temperature to room temperature at a frequency of about 1.5 Hz. We investigated relationship between peak height and volume fraction of austenite and, also cleared influence of microstructure on internal friction peak.(1) SUS304 austenitic stainless steel was cathodically charged with hydrogen. After charging, internal friction peak due to hydrogen was found at 260 K. This hydrogen induced peak height increased with increase of hydrogen content. Consequently it is apparent that this peak is attributed to hydrogen in austenite.(2) The internal friction peak was observed at 260 K in SUS329J1 duplex stainless steel subjected to hydrogen charging. However this peak was not found for SUS444 ferritic stainless steel. Therefore it is clear that this peak is associated with hydrogen in austenite in SUS329J1 duplex stainless steel.(3) The volume fraction of austenite for SUS329J1 duplex stainless steel and SMAW 329J4L and SMAW 329J3L weld metal was approximately 40%. The base metal has the microstructure with austenite elongated toward rolling direction in rod shape in ferrite matrix, and the weld metal has the microstructure with widmanstatten austenite in ferrite matrix. Hydrogen content and peak height value was plotted on same straight line, therefore their relationship is independent of microstructure morphology. The relationship between peak height and hydrogen content in austenite in SUS329J1 base metal is applicable to that of weld metal. Internal friction peak height due to hydrogen is proportional to volume fraction of austenite in case hydrogen content in austenite is same.

Mechanical measurement of vortex phase transition inYBa2Cu3O7+δ

Using the vibrating-reed technique, the internal friction (IF) ${Q}^{\ensuremath{-}1}$ and modulus as functions of temperature were measured for a ${\mathrm{YBa}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{7+\mathrm{\ensuremath{\delta}}}$ single crystal at low applied magnetic fields up to 0.5 T. The frequency dependence of the IF related to the vortex is reported. No obvious shift of the IF peak position can be observed by varying the measurement frequency ranging from ${10}^{2}$ to ${10}^{3}\mathrm{Hz}$ but the IF peak height satisfies a power law ${Q}^{\ensuremath{-}1}\ensuremath{\propto}{\ensuremath{\omega}}^{\ensuremath{-}n}$ $(1<n<2).$ This is speculated to originate from a phase transition associated with the melting or a glass transition of the vortex lattice. These results provide a fundamental measurement of the phase diagram of vortices in high-${T}_{c}$ superconductors.

Experimental and theoretical aspects of internal friction associated with the melting of embedded particles

Internal friction associated with the volume change during melting was studied in an aluminum-16 wt% indium alloy. This alloy was processed to obtain microstructures consisting of nominally pure indium inclusions embedded in an aluminum matrix. Two sharp internal friction peaks were observed near the indium melting temperature of 156°C and both were associated with the formation and growth of liquid nuclei. A general theoretical model for the internal friction was developed which incorporates both the rates of phase deformation and the relaxation of the surrounding matrix. The proposed model considers the effect of the hydrostatic stress generated during melting that initially opposes the transformation. Matrix relaxation around the transforming particles resulting from vacancy flux and dislocation climb contributes an additional frequency dependence to the internal friction. Both the matrix relaxation and the internal friction peak height were found to be dependent upon thermomechanical processing.

Effect of precipitation on internal friction of rapidly solidified AlSi alloys

The internal friction of rapidly solidified AlSi alloys with compositions of 0.96, 3.8 and 11.5 at.% Si was studied using a low frequency inverted torsion pendulum over the temperature region of 300–600 K. An internal friction peak was observed in the temperature range 350–550 K in the AlSi alloys. The Q −1 peak decreased during the second run, which was found to be directly related to the precipitation of silicon solutes from the supersaturated aluminium grains. We suggest that the internal friction peak in the AlSi alloys originates from grain boundary relaxation, but the grain boundary relaxation can also be affected by the silicon precipitates at the grain boundaries, which will impede grain boundary sliding. This makes the internal friction peak much smaller than that of a pure polycrystalline aluminium. The internal friction behaviour of the Al-3.8at.%Si alloy was investigated in more detail. The increase of the internal friction peak height with increasing annealing time in the Al-3.8at.%Si alloy may be attributed to the coarsening of the silicon precipitates at the grain boundaries.

THE STUDIES OF STRESS-INDUCED I/C TRANSITION AND INTERFACE DYNAMICS IN NiTi ALLOY

The internal friction (IF) Q-1, modulus f2, electrical resistance R and stress s of superelastic Ni51Ti49 alloy in the process of stress induced incommensurate/commensurate (I/C) transition was measured as a function of strain e by a middle torsion pendulum on a tensile testing machihe modified with a four-terminal potential equipment.The effects of number of stress cycles and strain rate e (in the range of 7×10-7/s to 1×10-4/s) were studied. An IF peak and a minimum of modulus were observed respectively in the Q-1-εand f2-εcurves. The IF peak height Qp-1 and modulus defect △M/M increase with an increasing of ε/ω, where ω is angular frequency of measuring. By utilizing an expression obtained from phase interface dynamics and experimental data of Qp-1 (as a function of ε/ω and amount of phase transition F), an explicit functional relationship of average I/C phase interface velocity V and effective phase transition driving force △G′= △G - △GR (where △GR is resistance) was derived as V =V*(△G - △CR)m, where V* and m are dynamic parameters an △GR is a resistance force exerting on the moving interface, which has the order of 1 cal/mol for stress-induced I/C transition of superelastisity NiTi alloy. The relationship between Q-1 and modulus defect △M/M and soft modulus effect are disussed.

Comparative investigation of infralow frequency internal friction in KDP and GMO crystals near their curie points

Abstract The dependences of internal friction peak height Q−1 m vs the rate of the temperature change Ť near Curie point at frequency of 10 Hz for proper (KDP) and improper (GMO) ferroelectric-ferroelastic crystals have been investigated. Principally different character of Q−1 m ([Tgrave]) slopes vs strain amplitude for samples where the external stresses make no strains coupled with the spontaneous strain has been found.

Internal friction mechanism in improper ferroelectric-ferroelastic Gd2(MoO4)3

The low-frequency internal friction features of the improper ferroelectric-ferroelastic Gd2(MoO4)3(GMO) have been studied. The equilibrium state of phase transition parameters of z -orientation samples used in the experiment are not changed by the applied external mechanical stresses. The internal friction peak height is found to be proportional to the temperature rate and inversely proportional to the frequency and amplitude of mechanical stresses. A loss mechanism of mechanical energy has been proposed. According to this mechanism the internal friction peak appearing near the Curie point is due to the interaction of antiphase boundaries with domain boundaries and dislocations.

THE BEHAVIOR OF INTERNAL FRICTION ASSOCIATED WITH THE PROCESS OF MARTENSITE-TYPE TRANSFORMATION

Internal friction in two kinds of iron-manganese alloy which contain Mn 17.5% and Mn 12.8% respectively and one kind of copper-aluminum alloy containing 13% Al were measured with a torsion pendulum, and internal friction peaks were observed in the temperature range in which the martensite or reverse martensite transformation is taken place. The condition for the appearance of this internal friction peak is that it occurs only when accompanied by the process of martensite-type transformation.Systematic observations were made with iron-manganese alloy containing 17.5% Mn, and it was found that the height of internal friction peak increases with the increase of the rate of heating (or cooling) or the stress, decreases with the increase of the frequency of vibration or the carbon content in the specimen. All these may be explained by the reason that the more the amount of new phase has transformed in one period of vibration, the larger is the internal friction.The mechanism of the internal friction peak was discussed. The conclusion was reached that because of the suddeness of the formation of martensite, the applied external forces due to torsion pendulum may be considered as constant during the time of formation for martensite plates, and since half of the work done by the external forces during the alteration must be lost as confirmed by the calculation of interaction energies between stresses and iuhomogenities, it consequently gives rise to the substantial portion of internal friction. On the other hand, the stress-induced phase transformation also gives rise to a minor portion of internal friction.

A STUDY ON THE DIFFUSION OF CARBON IN γ-IRON BY METHOD OF INTERNAL FRICTION

In γ-iron (containing 1.7% of Mn) an internal friction peak was observed around 240℃with a frequency of vibration of about 2 cycles per second. The height of the peak was found to increase with an increase of the carbon content and was found to decrease when the specimen was annealed at an elevated temperature. The activation energy associated with this peak was found to be 34,000±2,000 calories permole which is close to the activation energy of diffusion of carbon in y-iron determined in macro-diffusion experiments. It is concluded, thus, the observed internal frictionpeak is associated with the stress-induced diffusion of carbon in y-iron.The coefficient of diffusion D of carbon in y-iron in the temperature range of 200-260℃ was calculated according to data given by internal friction measurements. When plotted with logD against 1/T, these values of D were found to lie on the same straight line with those values of D in the temperature range of 1000-1200℃ determined in macro-diffusion experiments.The height of internal friction peak appeared to vary with the square of the carbon content in the specimen. This seems to indicate that two carbon atoms are participating in the elementary act associated with the stress-induced diffusion. A preliminary model for the observed internal friction peak was suggested thereupon: Owing to the presence of holes (vacancies) in the crystal lattice, two carbon atoms are apt to form an atomic-pair and this pair produces lattice distortions which are different along three crystallographic directions. Rotation of such an atomic-pair under the action of stress gives rise to internal friction.