Internal Friction Measurements Research Articles

Grain Boundary Internal Friction Peak in Nanocrystalline Aluminum Studied by Continuously Changing-Temperature

The bulk nanocrystalline aluminum are fabricated by cryomilling and hot-press sintering. The internal friction (IF) and relative dynamic modulus measurements in the nanocrystalline aluminum (Al) have been made using a multifunction internal friction apparatus (MFIFA) at low frequencies (0.2-3.0 Hz) over the wide temperature ranges from room temperature to 450 °C, while continuously changing-temperature forced vibration measurement. In the temperature spectrums of IF during heating process and cooling process, a distinct IF peak is found. Corresponding to the IF peak, the relative dynamic modulus decreases rapidly. The peak temperature of the IF peak shifts towards higher temperature with increasing frequency, i.e., the IF peak seem due to the thermal activated relaxation process. The IF peak is a grain boundary IF peak, which is associated with the diffusive grain boundary of Al/Al. Its activation energy has been calculated to be 2.21±0.04×10-19 J and the pre-exponential factor is 10-14 s in IF measurements.

Synthesis and characterization of mixed conductor CeNbO4

CeNbO4 samples were synthesized via solid state reactions and characterized by XRD, XPS, internal friction and impedance measurements. The XRD pattern showed that the sample quenched from 1173K to room temperature was mainly composed of monoclinic CeNbO4 phase. XPS analysis showed that the oxygen lattice can be present in form of Ce–O and Nb–O while niobium exists in Nb5+ state and cerium exists in both Ce3+ and Ce4+ states. One relaxation process was observed by the internal friction (IF) measurement, which was attributed to the short distance migration of interstitial oxygens. The activation energy of the IF peak is deduced to be 0.34eV. In the impedance measurement, the ionic transfer number estimated by impedance calculation was about 0.4. The activation energies for ionic conductivity (Eion), electronic conductivity (Ehole) and total conductivity (Et) were calculated to be 0.34, 0.29, and 0.64eV, respectively.

Non-Conventional Techniques for the Study of Phase Transitions in NiTi-Based Alloys

Differential scanning calorimetry and electrical resistance measurements are the two most common techniques for the study of the phase transition path and temperatures of shape memory alloys (SMA) in stress-free condition. Besides, it is well known that internal friction measurements are also useful for this purpose. There are indeed some further techniques which are seldom used for the basic characterization of SMA transition: dilatometric analysis, magnetic measurements, and Seebeck coefficient study. In this work, we discuss the attitude of these techniques for the study of NiTi-based phase transition. Measurements were conducted on several fully annealed Ni50−xTi50Cux samples ranging from 3 to 10 at.% in Cu content, fully annealed at 850 °C for 1 h in vacuum and quenched in water at room temperature. Results show that all these techniques are sensitive to phase transition, and they provide significant information about the existence of intermediate phases.

Is “strain glass” a nanodomain frozen transition?

Controversies on the “strain glass” concept are discussed in the present paper. Both ferroic glassy theory and traditional anelasticity theory can explain the “strain glassy behavior”. However, due to the limited frequency range of internal friction measurements, it is difficult to distinguish whether “strain glass” is a nanodomain frozen transition or thermally activated process.

Measurement of local internal friction in metallic glasses

Atomic force acoustic microscopy (AFAM), an advanced scanning probe microscopy technique, has been used to measure local elastic properties with a spatial resolution given by the tip-sample contact radius. AFAM is based on inducing out-of-plane vibrations in the specimen. The vibrations are sensed by the AFM cantilever from by the photodiode signal when its tip is in contact with the material under test. To measure local damping, the inverse quality factor Q−1 of the resonance curve is usually evaluated. Here, from the contact-resonance spectra obtained, we determine the real and imaginary part of the contact stiffness k* and from these two quantities the local damping factor Qloc−1 is obtained which is proportional to the imaginary part γ of the contact stiffness. The evaluation of the data is based on the cantilever's mass distribution with damped flexural modes and not on an effective point-mass approximation for the cantilever’s motion. The given equation is simple to use and has been employed to study the local Qloc−1 of amorphous PdCuSi metallic glass and its crystalline counterpart as a function of position of the AFM tip on the surface. The width of the distribution changes dramatically from the amorphous to the crystalline state as expected from the consequences of the potential-energy landscape picture. The center value of the distribution curve for Qloc−1 coincides very well with published data, based on global ultrasonic or internal friction measurements. This is compared to Qloc−1 measured in crystalline SrTiO3, which exhibits a narrow distribution, as expected.

Atomic relaxation processes in an intermetallic Ti–43Al–4Nb–1Mo–0.1B alloy studied by mechanical spectroscopy

An advanced intermetallic γ-TiAl-based alloy containing Nb and Mo has been studied to understand the microscopic mechanisms taking place during thermal treatments carried out to adjust a fine, nearly lamellar microstructure. The evolution of the microstructure has been characterized by high-energy X-ray diffraction and electron microscopy, while the atomistic mechanisms of defect mobility have been studied through internal friction and dynamic modulus measurements. An internal friction relaxation peak has been observed at about 1050K (for 1Hz) in the initial oversaturated α2-Ti3Al phase, whose intensity strongly decreases after precipitation of the γ-TiAl laths. The activation parameters of this relaxation have been measured, Hact=3.1±0.05eV, τ0=8.3×10−17s and β=1.3, and the relaxation is attributed to a point defect mechanism taking place inside the supersaturated α2-Ti3Al phase. A new Zener-like atomistic model based on stress-induced reorientation of Al–VTi–Al dipoles has been developed to explain the observed relaxation, resolving the controversy concerning the relaxation peak at 1050K present in many γ-TiAl-based alloys. Precipitation of the γ-lamellae has also been considered as being responsible for the dynamic modulus hardening and, additionally, for another contribution to the internal friction at higher temperature than the described relaxation. Finally, the theoretical Debye equations as a function of temperature, for both internal friction and dynamic modulus, have been applied, using the measured activation parameters, to perform a deconvolution of the relaxation and precipitation contributions. The obtained results agree well with the experimental ones at different frequencies, allowing a global interpretation of the involved atomic processes.

Internal friction and evolution of ultrafine-grained structure during annealing of Grade-4 titanium subjected to severe plastic deformation

Electron microscopy, X-ray diffraction, tensile tests, and measurements of internal friction (IF) have been used to study the transformation of the structure and properties of commercial Grade-4 titanium subjected to deformation using equal-channel angular pressing combined with the Conform process (ECAP-Conform), drawing, and subsequent annealing. It has been found that the ECAP-CONFORM with drawing leads to a decrease in the grain size of titanium to about 150 nm. During annealing at 400°C for 1 h, the growth of separate grains was observed; with an increase in the annealing temperature to 450°C or higher, the growth of grains in the whole volume of a specimen occurred. It has been shown that titanium in the ultrafine-grained (UFG) state is characterized by an internal-friction peak at temperatures of 450–500°C (under the selected measurement conditions), which results from the processes of recovery and recrystallization. During repeated heating, no such effect was observed. At higher temperatures, a thermally activated relaxation internal-friction peak was found, which appears to be a grain-boundary internal-friction peak.

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).

Fabrication and characteristics of melt-spun Al ribbons reinforced with nano/micro-BN phases

Melt-spun aluminum ribbons with up to 5wt.% of embedded nano/micro boron nitride (BN) phases, namely multiwalled BN nanotubes (BNNTs) or BN microparticles (BNMPs), were fabricated by melt-spinning in an argon atmosphere. The comparative structural characteristics were analyzed using X-ray diffraction, scanning and transmission electron microscopy, and internal friction measurements as a function of temperature within an 80–800K range. Room temperature tensile tests were carried out on ribbons. These revealed reinforcing effects on pure Al-matrices after nano/micro-BN embedment for both added phases with the notably higher numbers peculiar to the BNNT-containing samples. The intrastructural interactions between BN additions and Al-matrices are discussed based on the structural analysis and the internal friction data.

Investigation of the phase transition of Ge2Sb2Te5 films using internal friction method

The phase transition of Ge2Sb2Te5 has been studied by internal friction measurement. Two Q−1 peaks were observed during the process of heating amorphous Ge2Sb2Te5 from room up to 400°C. With a heating rate of 5.5°C/min, the first peak (P1) is located at 180°C and the second peak is (P2) located at 330°C. Only the peak P1 appears when sample has been beforehand annealed at 230°C for 1hour. Both the peaks P1 and P2 don’t appear when sample has been beforehand annealed at 380°C for 1hour. The positions of P1 and P2 are both affected by the heating rate, and they follow Kissinger relation. The activation energy corresponding to the peak P1 is 1.94±0.18eV, and the activation energy corresponding to the peak P2 is 3.49±0.24eV. The isothermal annealing experiment revealed that Q−1 monotonously decreases with time t in the process of phase change, and the internal friction Q−1 versus time t can be represented as Q−1(t)=Q−1(∞)−[Q−1(∞)−Q−1(0)] exp (−t/τ). The characteristic time τ is affected by temperature, and lnτ increase linearly with T−1.

Self-interstitial defects in hexagonal close packed metals revisited: Evidence for low-symmetry configurations in Ti, Zr, and Hf

In addition to the eight conventional high-symmetry configurations for self-interstitials in the hexagonal close packed (hcp) structure, we show that four other configurations, obtained by breaking the symmetry of some of the original ones, may be low-energy local minima or saddle points. The first two, BC${}^{\ensuremath{'}}$ and C${}^{\ensuremath{'}}$, consist of the basal crowdion and the crowdion buckled perpendicular to their axes in the pyramidal plane, respectively. The two others, PS and P2S, are obtained by rotating the $c$-axis split dumbbell in the prismatic plane of first and second type, respectively. Using first-principles density functional theory calculations we show that BC${}^{\ensuremath{'}}$, C${}^{\ensuremath{'}}$, and PS are within 0.4 eV of the lowest-energy conventional structure, BO, in Ti, Zr, and Hf. BC${}^{\ensuremath{'}}$ could even be the lowest-energy configuration in hcp-Zr and its symmetry and possible reorientation mechanisms are compatible with internal friction measurements at variance with the conventional structures. The PS and C${}^{\ensuremath{'}}$ configurations exhibit a helicoidal easy glide motion of the dumbbell-crowdion type in the $c$-axis direction. These configurations therefore constitute an important element to take into account when predicting the microstructural evolution of zirconium-based materials under irradiation.

Internal friction measurements of phase transformations during the process of deep cryogenic treatment of a tool steel

This paper reports internal friction measurements in die steel with the aim of clarifying phase transformation mechanisms during deep cryogenic treatment (DCT). Internal friction peaks appeared in the quenched sample and the DCT treated material during the process of cooling down to −160°C from room temperature (20°C) and then heating up to room temperature for multiple cycles in high vacuum. However, internal friction peaks do not appear in annealed material. It is concluded that the internal friction peaks are attributed to stress-induced martensite formation based on thermal hysteresis phenomena. That is, retained austenite is mostly transformed into martensite during the DCT.

Internal friction in silver-containing (Ag3AsS3) x (As2S3)100 − x superionic glasses

The mechanical properties of glasses in the Ag3AsS3-As2S3 system have been studied by the internal friction method. Measurements of internal friction and shear modulus have been carried out in the temperature interval 80–300 K at deformation frequencies of 10–50 mHz. Relaxation-type maxima of internal friction have been revealed. It has been shown that the concentration-induced variations in the parameters of the mechanical relaxation process in (Ag3AsS3) x (As2S3)100 − x glasses observed in the region of 20 at % Ag3AsS3 are of the threshold character. It has been established that this feature can be associated with the variation in the structural unit, which accounts for the process of mechanical energy dissipation within the temperature interval 150–250 K.

Effect of Isothermal Ageing on Damping Capacity of Cu-20.4Al-8.7Mn

The effect of ageing temperature on damping capacity of the Cu-20.4Al-8.7Mn alloy at room temperature was investigated by internal friction measurements. The results indicated that damping capacity of the alloy exhibits a non-monotonous changing trend with ageing temperature. Ageing at lower temperature of less than 150oC, damping capacity rapidly increses even up to maximum of 0.01 with the increasing ageing temperature, the reason of which should relate with the increased amount of twin boundaries and phase interfaces between martensites due to the thinning and splitting of martensitic plates, whereas when the ageing temperature exceeds 150oC, the damping capacity trends to steeply decrease as the ageing temperature increases until close to a constant in last corresponding to the ageing at higher temperature due to the occurrence and complete finish of transformation of martensites to austenites.

Mechanical properties of Ni0.83Co0.15Cu0.02Fe1.9O4−δ+PbZr0.52Ti0.48O3 particulate composites by composite oscillator technique and the correlation with the results of magnetoelectric properties

The xNi0.83Co0.15Cu0.02Fe1.9O4δ (NCCF) + (1−x)PbZr0.52Ti0.48O3 (PZT) particulate magneto ferroelectric composites with x = 0, 0.1, 0.2, 0.3, 0.4, 0.5 and 0.6 mole fraction were prepared by conventional ceramic double sintering method. The presence of two phases (perovskite structure of ferroelectric phase and spinal structure of ferromagnetic phase) was confirmed by X-ray diffraction. The magnetoelectric (ME) property of the particulate composites was determined at room temperature as a function of intensity of magnetic field. The temperature variation of the longitudinal modulus (L) and the internal friction (Q −1 ) of these particulate composites at 104.3 kHz was studied in the wide temperature range 30-420 ℃. The temperature variation of the longitudinal modulus in each composition of these particulate composites showed two abrupt minima. One minimum coincided with the ferroelectric - paraelectric Curie transition temperature (θE) and the other with the ferromagnetic-paramagnetic Curie transition temperature (θM). The internal friction measurement also showed two sharp peaks in each composition corresponding to those temperatures where the minima were noticed in the temperature variation of the longitudinal modulus behaviour.

Design, implementation, and application of a microresonator platform for measuring energy dissipation by internal friction in nanowires

Accurate measurements of internal friction in nanowires are required for the rational design of high-Q resonators used in nanoelectromechanical systems and for fundamental studies of nanomechanical behavior. However, measuring internal friction is challenging because of the difficulties associated with identifying the contributions of material dissipation to structural damping. Here, we present an approach for overcoming these difficulties by using a composite microresonator platform that is calibrated against the ultimate limits of thermoelastic damping. The platform consists of an array of nanowires patterned at the root of a low-loss single-crystal silicon microcantilever. The structure is processed using a lift-off technique, implemented using electron-beam lithography, to achieve excellent control over the size, alignment, dispersion and location of the nanowire array. As the first application of this platform, we measured internal friction at room temperature in aluminum nanowires that ranged from 50 to 100 nm in thickness and 100 to 400 nm in width. Internal friction is ∼0.03 at frequencies of 6.5–21 kHz. Transmission electron microscopy of the nanocrystalline grain structure, and comparison with previously measured values of internal friction in continuous thin films of aluminum, suggest that grain-boundary sliding is a major source of internal friction in these nanowires.

Phase transition and mechanical damping properties: A DMTA study of NiTiCu shape memory alloys

Internal friction measurement is a well-known investigation technique of the damping property of shape memory alloys (SMAs). It has already been demonstrated that this practice conducted in temperature scanning at a constant solicitation frequency is also useful in determining the path of the martensitic transformation and also the influence of hydrogen content on the martensitic properties. There is indeed a lack of studies about SMA internal friction as a function of solicitation frequency; systematic and rigorous analysis has not been reported yet. In this work the path of the martensitic transformation of Ni50−xTiCux alloys (x = 3–10at%) is investigated through Dynamic Mechanical Thermal Analysis (DMTA): internal friction as a function of temperature at a constant flexural frequency and internal friction as a function of flexural frequency at a constant temperature were evaluated. Results show that the two scans are both sensitive to phase transitions and microstructural changes.

Internal friction and dynamic modulus in Ru-50Nb ultra-high temperature shape memory alloys

The martensitic transformations in ultra-high temperature Ru-50Nb shape memory alloys have been studied by internal friction and dynamic modulus measurements. Two successive transformations from the high temperature cubic β phase to a tetragonal β′ martensite and then to another monoclinic β″ martensite have been found. Both transformations exhibit a sharp internal friction peak and a clear softening of the dynamic modulus, being a signature of the thermo-elastic martensitic transformations. In addition, a pseudo relaxation peak strongly dependent on time has been found and analyzed, concluding that it is linked to a pinning effect of martensite interfaces by point defects.

Microstructure of Low C Steel Isothermally Transformed in the M S to M f Temperature Range

An isothermal transformation was observed when a fully austenitized lean-alloyed, low C steel was quenched to a temperature in the MS to Mf temperature range and held at the quenching temperature. The dilatometric analysis revealed that the isothermal transformation was distinct from the bainitic transformation. Internal friction (IF) measurements and X-ray diffraction (XRD) analysis showed that the dislocation density in the isothermal transformation product was larger than in lower bainite, and lower than in athermal martensite. Microstructural analysis by transmission electron microscopy (TEM) revealed that the isothermal transformation product had a specific microstructure consisting of large lath-type constituent units with wavy boundaries, with a Nishiyama–Wassermann orientation relationship (NW OR) with respect to the parent austenite. The isothermal transformation below MS proceeds by the thickening of athermally formed laths.

Maxwell equation for conductivity of dielectrics as the basis of direct relationship of ionic electrical conductivity and mechanical losses in glasses. New problems of physical chemistry of glass

Use of the Maxwell equation for the conductivity of dielectrics and the theory of mechanical losses in glasses caused by ionic shifts has made it possible to calculate directly the temperature of the "ionic" max� imum of mechanical losses using data on direct current conductivity. The Maxwell equation was used without changes, in the view accepted in electromagnetic theory. An intuitive physicochemical interpretation of the nature of ionic conductivity measured at constant voltage as a relaxation process was suggested. Verification of the suggestion equation's validity was performed for onealkali glasses in silicate, borosilicate, phosphate, borate, and germanate systems. The ratio of calculated and experimental values of the temperature of the "ionic" internalfriction maximum corresponds to 0.995 ± 0.034 and does not depend on the frequency of measurements of internal friction (it changed by four orders) or the parameters characterizing conductivity. These results also confirm the validity of the Maxwell equation for the conductivity of dielectrics. The possi� bility of describing the direct current ionic conductivity of glasses as a Debye relaxation transition proved in this work is a consequence of the constant voltage condition. The design of a theory for the condition of nat� ural decay of a given potential, when the Kohlrausch relaxation regularity becomes valid, represents a princi� pally important problem of physics and physical chemistry of disordered systems.