Investigation Of Internal Friction Research Articles

Internal friction in thin-film ferrite bismuth with an amorphous structure

The internal friction spectra of an amorphous thin-film bismuth ferrite deposited on a silicon substrate were studied. The temperature dependence of mechanical losses near the glass transition temperature revealed a wide maximum of internal friction associated with α-relaxation of the amorphous structure. In this temperature region, two linear sections in the ln Q −1 vs (1/ T ) dependence are observed with an intersection point at the glass transition temperature. According to the results of low- and high-temperature internal friction investigation of the amorphous bismuth ferrite in the α-relaxation region, the values of the migration energy and the formation energy of vacancies-like defects were estimated, which are equal to E m = 0.80 ± 0.08 eV and E v = 0.88 ± 0.08 eV, respectively. • Internal friction Q −1 in amorphous bismuth ferrite BiFeO 3 at high temperatures was studied. • The Q −1 maximum is due to α-relaxation of the amorphous structure in thin-film BiFeO 3 . • Crystallization of the amorphous structure of BiFeO 3 is confirmed by the results of DTA and X-ray diffraction analysis. • Estimates of the migration energy and the formation energy of oxygen vacancies in the amorphous BiFeO 3 were made.

Investigation of internal friction and fracture fatigue entropy of CFRP laminates with various stacking sequences subjected to fatigue loading

The heat dissipation caused by internal friction plays an important role during fatigue property prediction based on self-heating data but it is still unclear for Carbon Fiber Reinforced Polymer (CFRP). In this paper, fatigue tests and thermal data analysis are carried out in order to investigate internal friction and Fracture Fatigue Entropy (FFE) of CFRP laminates with various stacking sequences. The fatigue limit is firstly estimated based on an improved graphic method developed by our previous study and then used to mark the beginning of fatigue damage occurs. It is found that the relationship between internal friction and applied stress amplitude is non-linear which is different from metals. Quadratic function is employed to characterize the internal friction region below fatigue limit and the trend line is used to separate heat dissipation related to damage and internal friction beyond fatigue limit. Results show that the internal friction effect of cross-ply laminates is significantly greater than that of unidirectional laminates. FFEs estimated by the heat dissipation related to damage are found to be independent of applied stress amplitude, which can be used to predict S–N curve of CFRP laminates efficiently and precisely.

Nanoscratch and internal friction investigations of deep cryogenic treated M2 high-speed steel

ABSTRACTThe influence of deep cryogenic treatment (DCT) on microstructure and tribological property of M2 high speed steel by means of nanoscratch and internal friction were discussed. The results obtained have shown that the wear resistance of M2 high speed steel after DCT treatment was superior to that of quenched samples. The formation of alloy carbides affected the height of the Snoek-Köster-Kê (SKK) peak during cryogenic treatment, making the decrease of the SKK peak. Long-time isothermal cryogenic treatment is not benefit for frictional properties of M2 high speed steel.

Role of defectivity on the crystallography of martensitic transformations in Ti50Ni40Cu10: an XRD investigation

Abstract Martensitic transformations in Ni50Ti40Cu10 are well known to proceed with a two-step process, from B2 austenite to monoclinic B19′ with intermediate orthorhombic B19. These transformations can be readily followed by X-ray diffraction especially in solution heat-treated materials through split and distribution of the main diffraction lines, while peaks broadening and overlap make the transformations more difficult to be described in highly defective materials. The present study addresses the effect of defects and chemical inhomogeneities on the martensitic transformation, placing particular emphasis on the crystallography of the low temperature B19 to B19′ phase transition. Lattice strains proved to be a powerful tool to monitor the martensitic transformations: whereas a clear discontinuity is observed for the solution heat-treated sample, defects promote a continuous progressive distortion from B19 to B19′. Calorimetry and internal friction investigations were added as a reference to verify the occurrence of the transformations and define the corresponding temperatures.

Investigation of Internal Friction of Agglomerated Dry Ice

The article presents results of research on internal friction of agglomerated dry ice. The results allowed for approximations of the curve describing the relation between the material parameters as a function of limit compression stress of the agglomeration process of dry ice. The value of parameter of investigated material is needed to formulate a mathematical model. This model can describe the influence of geometrical parameters of the conical channel on the limit stress in the process of agglomeration of dry ice. Due to the fact that the crystallized carbon dioxide has temperature equal minus 78.5°C and sublimates under normal conditions of the test there was proposed the methodology which allowing performance the tests. The study determined the curve describing the change of cutting stress vs. deformation. The tests were realized for samples having different degrees of densification. This allowed to describe the relation between shear stress and degree of densification of the agglomerated dry ice. Results will allow for formulation of assumptions, which will be one of main point to create a more efficient machine for agglomeration process of solidified carbon dioxide.

The Investigation of Internal Friction on Antiferromagnetic Transition and Martensitic Transformation in Mn-Fe(Cu) Alloys

The internal friction and elastic modulus variations caused by the structural rearrangement fcc↔fct in Mn-Fe (Cu) antiferromagnetic alloys were studied in this paper. Antiferromagnetic transition exhibits weak first-order features due to the formation of microtwins by modulus softening mechanism. Antiferromagnetic transition also assists subsequent transformation to form twinned martensite. The small hysteresis between direct and reveres martensitic transformations indicates the thermoelastic feature. Both the martensitic and its reverse transformations also depend on the modulus softening mechanism.

Antiferromagnetic Transition and Martensite Transformation in γ-Mn-Fe Alloys

The detailed investigation of internal friction and relative dynamic modulus has been carried out for the γ-MnFe alloys with 61.4at%~86.4at%Mn in the temperature range from -50 to 250 using LMR by means of force vibration method. The internal friction was found to exhibit in turn three peaks from higher temperature to the lower temperature on the internal friction-temperature curves. They are PA,PM and PT progressively. It can be concluded that PA may be connected with the stress-induced motion of magnetic domain. The PM was suggested to be originated from the stress-induced movement of interfaces between the fcc and fct phases. The PT is due to a relaxation process associated with the movement of the {101}-twin boundaries in the fct phase or fcc antiferromagnetic phase.

Internal friction investigation of reverse martensitic transformation in oil-quenched Ni64Al36alloy

Low-frequency internal friction investigation of reverse martensitic transformation in oil-quenched Ni64Al36 alloy has been carried out using a multifunctional internal friction apparatus from room temperature to 400 °C and additionally differential scanning calorimetry and X-ray diffraction experiments were also completed. It has been shown that an internal friction peak presents at about 220 °C in the internal friction–temperature curve during heating for the oil-quenched Ni64Al36 alloy but not for the furnace-cooled Ni64Al36 alloy. The peak still appears during cooling and the peak temperature shifts to lower temperature. The changes of the peak temperature positions cannot be visibly observed when the vibration frequency is changed. The peak heights increase with decreasing vibration frequency and increasing heating rate, being linearly directly proportional to It has been suggested that the internal friction peak results from reverse martensitic transformation of L10 → γ during heating and originates from martensitic transformation of γ → L10 during the subsequent cooling process. The influence of the thermal cycles on the transformation is not observed for the limited thermal cycles. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Inelastic Relaxation in Tin Dioxide Thin Films

Internal friction results obtained in thin SnO2 films produced by reactive magnetron sputtering (thickness of the film ~ 1 μm) and by the dehydration of water solution of tin salts (thickness of the film ~ 10 μm) are reported. It is suggested that internal friction peak observed in SnO2 films at around 170 oC is caused by relaxation processes on grain boundaries (average grain size is 20 nm). The investigation of internal friction in SnO2 films can yield new information about the structure of thin films.

Internal friction investigation of phase transformation in nearly stoichiometric LaMnO 3+ δ

Rhombohedral LaMnO 3+ δ powders, prepared by two different soft chemistry routes (co-precipitation and hydrothermal synthesis), are sintered at 1400 °C for 2 h in air. Measurements of internal friction Q −1( T) and shear modulus G( T), at low frequencies from −180 to 700 °C under vacuum, evidence three structural transitions of nearly stoichiometric orthorhombic LaMnO 3+ δ . The first one, at 250 or 290 °C, depending on the processing followed, is associated to either a Jahn–Teller structural transition or a phase transformation from orthorhombic to pseudo-cubic. The second one at 610 or 630 °C is related to a phase transformation from pseudo-cubic or orthorhombic to rhombohedral. Below the Neel temperature, around −170 °C, a relaxation peak could be associated, for samples prepared according to both processing routes, to the motion of Weiss domains.

The investigation of internal friction and elastic modulus in surface nanostructured materials

In this paper, 304 stainless steel and pure Fe specimens, which were processed by high-energy shot peening (HESP) and ultrasonic shot peening (USP) respectively, were studied by the internal friction method. Measurements were carried out on a vibrating reed apparatus. The change of internal friction and elastic modulus shows that the treatment duration of specimen is not accompanied by the corresponding persistent increase of internal friction and elastic modulus. There is a transition layer from the top surface to the inside of the materials. Young's modulus of surface shows obviously a fluctuation along the depth profile. The phenomena have never been shown by other measurement methods. The microstructure change should be related to some basic mechanism of surface layer formation. It may also explain why the improvement of mechanical properties in surface nanocrystallized materials does not simply correspond to the duration time of severe deformation. (C) 2003 Elsevier B.V. All rights reserved.

Investigation of internal friction in chalcogenide glasses at sound frequencies

Investigation of internal friction in chalcogenide glasses at sound frequencies

DTA and Internal Friction Investigations of Phase Transformations for Se100 —xInx Chalcogenide Glasses

Glassy samples of the system Se100—xInx, (where x = 5, 10, 15 and 20 at%) were prepared by the usual melt-quenching technique, and their amorphous nature was identified by X-ray diffraction. The phase transformations (glass–amorphous, amorphous–crystalline and melting) were studied by two methods, that of Ozawa and Kissinger. The DTA thermograms of the samples were recorded at heating rates 10, 30 and 50 K/min. The glass transition temperature (Tg), the crystallization temperature (Tcp), and the melting temperature (Tm) were found to be heating rate dependent. The calculated values of the activation energy of crystallization were 13.3, 33.76, 18.52, 15.27 kcal mol—1 (by Kissinger's method) and 11.71, 29.79, 14.99, 14.89 kcal mol—1 (by Ozawa's method) for the compositions x = 5, 10, 15 and 20 at% respectively. The internal friction Q—1 as a function of temperature was investigated by a magnetostrictive technique for the Se95–In5 glass in the frequency range 30 to 50 kHz. Two well-defined peaks appeared and confirmed those observed by DTA measurements of this work.

Internal friction measurements of the effects of the electrochemical-abrasive treatment of titanium alloy

The influence of electrochemical grinding on the properties of WT3-1 titanium alloy is studied by the method of mechanical spectroscopy. On the basis of the experimental investigation of internal friction (with and without taking into account the amplitudes), it is shown that the formation of hydride phases is accompanied by the appearance of dislocations with complicated structure and the formation of stresses.

Characterization of the thermoelastic martensitic transformation in a NiTi alloy driven by temperature variation and external stress

In order to test the concept of the physics of dissipation during first-order phase transitions in solids, we measured the internal friction ${(Q}^{\ensuremath{-}1})$ and the relative shear modulus $(\ensuremath{\mu})$ during a thermoelastic martensitic transformation in a NiTi alloy. We adopted two approaches: temperature variation and application of external stress. This investigation of internal friction was carried out with various vibration frequencies \ensuremath{\omega}, temperature variation rates $\stackrel{\ifmmode \dot{}\else \.{}\fi{}}{T},$ and strain variation rates $\stackrel{\ifmmode \dot{}\else \.{}\fi{}}{\ensuremath{\varepsilon}}.$ The index $l$ (coupling factor between phase interface and oscillating stress) and index $n$ (rate exponent for the effective phase transformation driving force) have been calculated from the experimental data for each case and the values of $l$ and $n$ are about the same in the two (doped) NiTi samples, irrespective of whether the phase transition is driven by a temperature variation or stress induced process. We compare the values of $n$ and $l$ for the NiTi samples with that of the other samples (${\mathrm{VO}}_{2}$ ceramics and FeMn alloys), reinforcing the previous physical interpretations of these indices. We believe the indices $n$ and $l$ are indeed fingerprints of first-order phase transitions in solids.

Dislocation-like relaxations in cold deformed metallic glasses

The results of low temperature (30–300 K) low frequency (10 2–10 3) Hz) internal friction investigations of cold deformed metallic glasses (MGs) are summarized. It is shown that inhomogeneous deformation results in a number of internal friction anomalies which are almost identical to those in predeformed crystalline metals. Internal friction of as-cast MGs has no peculiarities. The main features of damping in cold-worked MGs consist in the appearance of (i) large relaxation internal friction peaks analogous to the well-known Hasiguti peaks in crystals and (ii) hysteresis damping which can be suppressed by large predeforming or irradiation. It is argued that inhomogeneous deformation of glassy structures results in the appearance of new dislocation-like defects, not characteristic of the as-cast state, which determine the observed anelastic anomalies.

Internal Friction Investigation of the γ-Peak Irreversibility in High Purity Tantalum and Niobium

Internal Friction Investigation of the γ-Peak Irreversibility in High Purity Tantalum and Niobium

Dislocation Internal Friction Investigation in High Purity Cold Worked Tantalum

After a low temperature deformation of high purity tantalum, an internal friction apparatus permits the measurement of the torsion plastic strain versus temperature as well as internal friction and modulus change. This kind of observation shows that in an intermediate temperature range (230 to 350 K) the glide on the {211} plane becomes active, and that the HCW-peak presents a sub-structure that can be revealed by some deformation and annealing procedure in this temperature range. The morphology of this „intermediate”︁ dislocation microstructure is characterized by long screw-dislocations with long kinked segments associated to jogs of considerable height. The HCW2-peak which appears after ageing in the 230 to 350 K range, is due to the {110} kink diffusion of long kinked segments on screw dislocations and the HCW1-peak is caused by KPF on 71° -edge-dislocations formed by the annealing above 400 K. Nach Tieftemperaturverformung von hochreinem Tantal, erlaubt eine Innere-Reibungs-Meßapparatur die Bestimmung der Temperaturabhängigkeit der plastischen Torsionsverformung, wie auch der inneren Reibung und des Moduldefektes. Diese Art von Untersuchung zeigt, daß in einem mittleren Temperaturbereich (230 bis 350 K) die Verschiebung auf der {211}-Ebene aktiv wird, und daß das HCW-Maximum eine Substruktur besitzt, die durch bestimmte Verformungen und Temperungen in diesem Temperaturbereich aufgezeigt werden können. Die Morphologie dieser „mittleren”︁ Versetzungs-Mikrostruktur wird charakterisiert durch lange Schraubenversetzungen mit langen gekinkten Segmenten, die mit Jogs von beträchtlicher Höhe verbunden sind. Das HCW2-Maximum, das nach Anlassen im 230 bis 350 K Bereich auftritt, stammt von der {110}-Kink-Diffusion von langen gekinkten Segmenten auf den Schraubenversetzungen. Das HCW1-Maximum wird durch KPB auf 71° Versetzungen ausgelöst, die durch Anlassen über 400 K verursacht werden.

An investigation of internal friction within the incubation period of the bainitic transformation

By the use of a new-designed internal friction instrument, automatically controlled by a microcomputer, in which specimen is heated by means of the radiation focusing of infrared ray and quenched by argon spraying, changes in internal friction and frequency during the course of bainitic transformations in 18Cr2Ni4WA steel and Cu-25.83Zn-3.96Al(wt%) alloy are measured. Experimental results show that there exists an internal friction peak associated with the lowering of frequency within the incubation period and Q −1 max increases and the time required for getting Q −1 max decreases with the decrease of the incubation period. It may be argued that the structural change within the incubation period is a nucleation process accompanying the local softening and/or lattice instability of the parent phase.

Frequency dependence of internal friction of plain metals for structural use.

Many investigations of internal friction of metals have been made so far. But, few well-ordered data of frequency dependence of loss factors have been obtained. Furthermore, it seems that incorrect constants of the three element model for visco-elasticity of metals are used sometimes. Therefore engineers who deal with structural vibrations can hardly know damping characteristics of materials. Then measurements of internal friction of mild steel, brass and alminum are made by use of bending, longitudinal and torsional vibrations. The obtained data of loss factors are arranged in relation to frequency. These metals show similar tendencies of damping to one another.