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Materials Research, Volume: 21 Suplemento 2, Publicado: 2018
  • Measurement of Strain-Amplitude Dependent Internal Friction with Torsion Pendulum and Vibration Reed Methods Articles

    Fang, Qianfeng; Wang, Xianping; Zhuang, Zhong

    Resumo em Inglês:

    In the traditional standard of internal friction measurement the torsion pendulum and vibration reed were preferentially recommended where the issue of strain amplitude dependence of internal friction was not concerned. To more precisely measure the internal friction and modulus at various strain amplitude, in this paper the strain amplitude dependence of internal friction and modulus is considered by analyzing the stress distribution in the sample in different internal friction measurement methods. The formulas for the measurement of internal friction and modulus versus strain-amplitude are obtained by re-deriving the principal equations for internal friction and modulus measurements by torsion pendulum and vibration reed methods from the basic definition of internal friction. This provides a new standard for precise measurement of internal friction at different strain-amplitude in the cases of high strain-amplitude excitation or high damping materials where amplitude dependent effects always appear.
  • Diverging Relaxation Times of Domain Wall Motion Indicating Glassy Dynamics in Ferroelastics Articles

    Puchberger, Sabine; Soprunyuk, Viktor; Schranz, Wilfried

    Resumo em Inglês:

    Single crystals of PbZrO3 and LaAlO3 have been studied by Dynamic Mechanical Analysis measurements in the low frequency range f = 0.02-50 Hz. The complex Young's modulus exhibits a quite rich behavior and depends strongly on the direction of the applied dynamic force. The low frequency elastic response in the [110]c-direction is dominated by domain wall motion, leading to a superelastic softening effect below Tc. With decreasing temperature this superelastic softening gradually disappears, due to an increasing relaxation time τDW of domain wall motion. For PbZrO3, τDW seems to diverge at a finite temperature TVF, indicating glassy behavior of domain freezing.
  • An Overview of Research into Low Internal Friction Optical Coatings by the Gravitational Wave Detection Community Articles

    Abernathy, Matthew Robert; Liu, Xiao; Metcalf, Thomas H.

    Resumo em Inglês:

    The direct detection of gravitational waves by ground-based interferometric gravitational wave detectors in recent years has opened a new window of the universe, allowing the astrophysical observations of previously unexplored phenomena, such as the collisions of black holes and neutron stars. However, small thermodynamic fluctuations of the density of the thin films that compose the mirrors used within the gravitational wave detectors, such as the LIGO and Virgo detectors, give rise to noise which limits these instruments at their most sensitive frequencies. This "Brownian Thermal Noise" can be related to the inherent internal friction of the mirror materials through the fluctuation-dissipation theorem. Therefore, the improved sensitivity of gravitational wave detectors depends, to some extent, upon the development of optical thin films with low internal friction. The past two decades have therefore seen the growth of internal friction experiments undertaken within the gravitational wave detection community. This article attempts to summarize the results of these investigations and to highlight current research directions in order to foster a stronger dialogue with the larger internal friction and mechanical spectroscopy community.
  • Mechanical Loss Angle Measurement for Stressed thin Film Using Cantilever Ring-Down Method Articles

    Kuo, Ling-Chi; Pan, Huang-Wei; Huang, Shu-Yu; Chao, Shiuh

    Resumo em Inglês:

    Mechanical loss of the coating materials, and hence thermal noise from the mirror coatings, is a limiting factor for the sensitivity of the laser interferometer gravitational waves detector at its most sensitive frequency range. Mechanical loss of the thin films are often measured using the cantilever ring-down method. But when the thin film is under stress, the regular ring-down method gives incorrect results. We report a method to obtain the mechanical loss of stressed thin film using the cantilever ring-down technique. A proof-of-concept example is given to demonstrate and verify our method. The method can also be applied to obtain the mechanical loss angle of a rough interface; an example showed that loss angle of the interface between silicon nitride film deposited by plasma enhanced chemical vapor deposition method and silicon substrate is highly frequency dependent.
  • Carbon Distribution in Ferritic-Martensitic Fe-Cr-C Alloys Articles

    Konstantinović, Milan Jovan; Minov, Boris; Renterghem, Wouter Van

    Resumo em Inglês:

    Carbon distribution in Fe-Cr-C alloys with a variety of Cr concentrations is studied based on internal friction, optical and transmission-electron microscopy. It is found that the carbon distribution strongly depends on initial microstructure, being ferritic or ferritic/martensitic, which is determined by the thermal treatment, and Cr and carbon concentrations. In the quenched alloys, carbon is observed in the form of small carbon-vacancy complexes, most probably two carbon - single vacancy cluster, 2CV, that dissolve at about 500 K. In tempered alloys, the carbon atoms are observed to be uniformly distributed only in Fe-2.5Cr-C alloy, which is fully ferrite. In the alloys with 5-12% of Cr, with ferritic/martensitic microstructure, carbon-Snoek relaxation peak is not observed due to the carbon precipitation, as well as due to atomic carbon being trapped at dislocations and grain boundaries. In both quenched and tempered alloys, the plastic deformation causes the appearance of the broad relaxation peak close to 300 K which could be assigned to dissolution of single carbon - single vacancy, CV, complexes.
  • Low-Temperature Anelastic Property of Nanocrystalline Ag Fabricated by Gas Deposition Method Articles

    Xi, Terigele; Suzuki, Ryoma; Tanimoto, Hisanori

    Resumo em Inglês:

    It was reported that the internal friction (Q-1) of nanocrystalline (n-) Au and n-Cu showed a rapid increase linearly with temperature above ~200 K. Since the rapid increase in Q-1 decreased with the progress in the grain growth, it was suggested that the anelasticity of grain boundaries in n-Au and n-Cu was thermally activated above ~200 K. In order to pursue the intrinsic behavior of the grain boundaries in n-metals, the internal friction of n-Ag was measured and the result was compared with those of n-Au and n-Cu. Similar to n-Au and n-Cu, Q-1 of n-Ag was also showed the increase linearly with temperature above ~200 K. However, the onset temperature for the linear increase in Q-1 of n-Ag was slight lower than those of n-Au and n-Cu and it can be attributed to the lower activation energy of the grain boundary self-diffusion in Ag.
  • Damping of the Woodwind Instrument Reed Material Arundo donax L Articles

    Weidenfeller, Bernd; Lambri, Osvaldo Agustín; Bonifacich, Federico Guillermo; Arlic, Uwe; Gargicevich, Damian

    Resumo em Inglês:

    The viscoelastic properties (E', G', tanΦ, δ) of Arundo donax (AD) and a polypropylene-beech fiber composite (PPC) were measured from RT to 580K for various frequencies and strains. E' of AD varies between 5250-6250MPa depending on ageing at RT while E'(RT)=2250MPa of PPC is signifcantly lower. E' of the AD is higher than E' of PPC in the whole investigated temperature range with the exception of AD after a heat treatment up to 575K. Damping spectra exhibit peaks around 340K (Q=234kJ/mol) and 415K for the PPC related to relaxations in the crystalline part of polypropylene and the relaxation at melting temperature. For AD damping peaks were found at 350K (Q=320kJ/mol) related to the glass-rubber transition of lignin, at 420K due to a reorganization in the amorphous phase of lignin, at 480K related to micro-Brownian motions in the non-crystalline region of cell-wall polymers and reduction of the crystallinity of cellulose, and at 570K due to the polymeric compounds of wood and/or a decomposition of lignin. The course of E' and tanΦ of AD and PPC is comparable from 20-200Hz, whereas tanΦ of AD is lower than tanΦ of PPC while E' of AD is higher than E' of PPC.
  • Relaxational Dynamics in the PYR14-IM14 Ionic Liquid by Mechanical Spectroscopy Articles

    Paolone, Annalisa; Palumbo, Oriele; Trequattrini, Francesco; Appetecchi, Giovanni Battista

    Resumo em Inglês:

    The anelastic spectrum of the N-butyl-N-methyl-pyrrolidinium (trifluoromethanesulfonyl) (nonafluorobutanesulfonyl)imide (PYR14-IM14) is reported for the first time. On cooling, at 4 Kmin-1 the sample undergoes a glass transition around 190 K. In the liquid phase, a thermally activated relaxation process is measured and it is analyzed by means of a modified Debye model. The best fit results indicate that the peak is related to the ion hopping between non-equivalent configurations which are mainly defined by the anion conformer configuration.
  • Piezoelectricity from Elastic and Dielectric Measurements on Unpoled Ferroelectrics Articles

    Cordero, Francesco

    Resumo em Inglês:

    A method is described to assess the piezoelectric response of ferroelectric materials from the temperature dependence of the elastic moduli and dielectric constant of unpoled samples. The limits and advantages over the traditional methods on poled samples are discussed. A quantitative check is made by comparing the piezoelectric softening measured below the ferroelectric transition in the Young's modulus of unpoled ceramic BaTiO3, with the appropriate angular average of the single crystal material constants from the literature. The softening effect of porosity has been taken into account by comparing the moduli of samples with different densities.
  • Amplitude-Dependent Internal Friction Study of Fatigue Deterioration in Carbon Fiber Reinforced Plastic Laminates Articles

    Nishino, Yoichi; Kawaguchi, Ryota; Tamaoka, Satoshi; Ide, Naoki

    Resumo em Inglês:

    The amplitude-dependent internal friction in carbon fiber reinforced plastic (CFRP) laminates subjected to fatigue cycling has been measured and analyzed to convert into the plastic strain of the order of 10-8 as a function of effective stress. The microplastic flow indeed occurs in the stress range three orders of magnitude lower than the failure stress, and the stress-strain curves tend to shift to a lower stress as the number of cycles increases, thus indicating a decrease in the CFRP strength. The microflow stress at the plastic strain of 1×10-8 keeps a constant value of about 0.4 MPa in the range less than 103 cycles but then decreases gradually, whereas the Young's modulus evaluated from the resonant frequency is almost constant up to 104 cycles where only transverse cracks are found. Thus we can successfully detect the onset of fatigue deterioration by means of the amplitude-dependent internal friction.
  • Manipulation of Glassy State in Amorphous Selenium by Low-temperature Internal Friction Measurements Articles

    Liu, Xiao; Metcalf, Thomas Harker; Abernathy, Matthew Robert; Stephen, Richard Burnite

    Resumo em Inglês:

    We have studied the thickness and quench-rate dependent internal friction of amorphous selenium (a-Se) thin films deposited at room temperature. The internal friction of a-Se films exhibit a temperature independent plateau below 1 K followed by a broad maximum at 10 K. The plateau, which is seen in almost all amorphous solids, is caused by dissipation by two-level tunneling systems (TLS), whose origin is still unknown. The maximum is caused by thermal relaxation over the same energy barrier that induces TLS. The internal friction and shear modulus are almost thickness independent from 100 nm to 10 µm. Unlike other elemental amorphous materials, the sufficiently low glass transition temperature (Tg) of a-Se (only about 10 K above room temperature) allows in-situ quench-rate dependent study of TLS. The amorphous structure resets itself by a thermal equilibration cycle above Tg. We show that a faster quench rate freezes a-Se to a lower density structure with a higher TLS density and vice versa. The changes are reversible supporting a relationship between different quenched states and the density of TLS. Our study shows that a-Se can be a simple monatomic amorphous system to constrain models for the origin of TLS in amorphous solids.
  • Anelasticity of Phase Transitions and Magnetostriction in Fe-(27-28%)Ga Alloys Articles

    Golovin, Igor Stanislavovich; Palacheva, Valeria Valerievna; Emdadi, Aliakbar; Mari, Daniele; Heintz, Alexei; Balagurov, Аnatoliy Mikhailovich; Bobrikov, Ivan Anatolievich

    Resumo em Inglês:

    Several aspects of anelastic behavior of Fe-(27-28%)Ga-Tb alloys are considered in this paper: (i) the phase transitions from a metastable to an equilibrium phase and phase transitions between equilibrium phases at higher temperatures in as cast alloys, (ii) the nature of corresponding three transient anelastic effects, (iii) the formation of an intrinsic composite microstructure with a different ratio between the bcc-derivative metastable and fcc-derivative equilibrium phases that have different magnetostriction and the effect of alloys doping by Tb to stabilize the metastable phase with high positive values of magnetostriction.
  • Annealing and Extended Etching Improve a Torsional Resonator for Thin Film Internal Friction Measurements Articles

    Metcalf, Thomas; Liu, Xiao; Abernathy, Matthew Robert

    Resumo em Inglês:

    We evaluate two methods to improve the background internal friction of the Double Paddle Oscillator (DPO), which has a nominal low temperature value of Q-1 ≈ 2×10-8. We find that annealing the DPO in vacuum at 300°C for 3 hours systematically reduced Q-1 at all temperatures and revealed a 100K internal friction peak by permanently removing it. We also find a striking decrease of low temperature Q-1 as the DPO geometry is altered through extended etching. This decrease is evaluated via Finite Element Method modeling in terms of mode mixing and attachment loss.
  • The Hydrogen Cold Work Peak in BCC Iron: Revisited, with First Principles Calculations and Implications for Hydrogen Embrittlement Articles

    Gibala, Ronald; Counts, William Arthur; Wolverton, Christopher

    Resumo em Inglês:

    We examine experimental and theoretical results on the cold-work (Snoek-Köster) peak in bcc Fe due to H using density functional theory (DFT). We reaffirm that Seeger’s interpretation of the H cold-work peak (Hcwp), involving motion of H with kinks on non-screw dislocations associated with the intrinsic-dislocation α peak, has experimental backing. Use of the solute-dragging theory of Schoeck suggests a H-mixed dislocation binding energy of 0.3 eV. The theory of Hirth, that the Hcwp involves H-screw dislocation interaction manifested as the temperature-reduced intrinsic-dislocation γ peak by the presence of H, has merit in that our DFT calculations disclose a similar magnitude, 0.2 eV, of H-screw dislocation binding. This result offers support for models of H-enhanced localized plasticity of H embrittlement. We also explore possible roles of H-vacancy binding, shown by DFT to be characterized by a binding energy of 0.6 eV, in H trapping and H embrittlement and lesser effects of H-solute binding involving small binding energies of ~ 0.1 eV.
  • Hysteretic Behavior of Twin Boundary Peak Due to Precipitation in Co-Ni-Cr alloy Articles

    Cosimati, Raffaele; Mari, Daniele

    Resumo em Inglês:

    Anelastic behavior and microstructural changes of a Co-Ni-Cr super-alloy were monitored over the temperature range 250-950ºC, by using several complementary techniques. Two grades of this alloy were used, differing by the presence of small quantity of beryllium (<1.5% at.). Thermoelectric power reveals two distinct precipitation stages. The first precipitation ("A"), common to both the grades, and a second one ("B"), occurring solely in the beryllium-containing alloy. Cold-worked alloys exhibit a transient large mechanical loss peak, associated to the recrystallization of the deformed materials, and two relaxation peaks situated at around 600ºC (P1) and 780ºC (P2). Instead, only the peak P1 occurs on the fully recrystallized material. P1 and P2 can be associated to the diffusion process involved in the first precipitation stage ("A") and to the twin boundary motion, respectively. The precipitation-dissolution process of precipitates "B", localized on the twin boundary, provides a hysteretic behavior of the peak P2.
  • Frozen-to-jamming-to-fluid Transition of Weakly Sheared Granular Systems by Low-frequency Mechanical Spectroscopy Articles

    Tang, Hanyu; Wang, Na; Liu, Changsong; Wu, Xuebang

    Resumo em Inglês:

    Granular matter usually displays frozen, jamming and fluidized states when submitted to an external vibration with increasing intensity. The dissipation properties of granular systems with three different millimeter-size glass grains (0.1, 0.5 and 1.9 mm) have been investigated by a modified low-frequency inverted torsion pendulum under a shear strain and an external pressure. With increasing the immersed depth of the oscillating probe, all the systems show the frozen, jamming and fluidized behaviors. Furthermore, the critical depth at which the transition occurs increases with increasing grain size, but decreases with the application of pressure. A qualitative explanation is tentatively proposed to understand the underlying mechanism of complex viscoelastic properties of the glass particle systems.
  • Impact of Alloy Composition and Thermal Stabilization on Martensitic Phase Transformation Structures in CuAlMn Shape Memory Alloys Articles

    Arlic, Uwe; Zak, Hennadiy; Weidenfeller, Bernd; Riehemann, Werner

    Resumo em Inglês:

    Alloys of CuAlMn are known as cheap, high strength shape memory alloys with an excellent damping capacity within their austenitic-martensitic phase transformation, compared to alloy systems like NiTi, CuZnAl or MnCu. But CuAlMn alloys have disadvantage due to generation of voids by a high shrinkage which further increases the existing proneness to stress cracks during rapid cooling. Alloying grain refining elements improves the stress crack resistance and enables a wide range of rapid quenching parameters which are needed to control the temperature of martensitic phase transformation. Additionally, the elements itself influence the in- or decreasing of the phase transformation temperature and the SMA effects. Furthermore, some of these elements can reduce the internal friction indirectly by decomposing areas of metastable martensite into its stabilized forms, where no transformation occurs. This thermic stability can be calculated by the concentration of valence electrons in a unit cell. The proneness to ageing is controlled by multistep heat treatments. Annealing and rapid quenching into the area of martensitic phase transformation maximize the generation of point defects. A high amount of point defects contradicts the negative effect of pinning. It also preserves the material from extreme brittleness. The influences of these effects are shown at single cantilever bending beams by elastic strain amplitude (ε = 12E-4) depending measurements of internal friction at natural frequency along the ageing at room temperature (293 K) up to 2500 h. The samples are annealed at 1123 K for 15 min (CuAl14Mn2) and 1100K for 30min (CuAl11Mn5) afterwards rapid quenched to 370 K with no further thermic stabilisation. The base alloy of CuAl14.1Mn2.0Ni1.9Fe0.4 had an internal friction measured as logarithmic Decrement (δ) of 0.155 and 0.11 after 2500 h of ageing at RT. The phase transformation is located between 284 K and 352 K, measured by DSC. The alloy of CuAl11.1Mn5.5Zn2.9Ni2.1 had a logarithmic decrement of 0.31 and diminish continuously to 0.12 after 2500 h of ageing at RT. The phase transformation is located between 287 K and 318 K.
  • Damping of Fe-Al Alloy Electrodeposited in an Ionic Liquid Articles

    Lambri, Osvaldo Agustin; Weidenfeller, Bernd; Bonifacich, Federico Guillermo; Pulletikurthi, Giridar; Xu, Jiayi; Weidenfeller, Laura; Endres, Frank

    Resumo em Inglês:

    Iron-Aluminium alloys were produced by the electro-deposition of iron-aluminium on a copper substrate. The electro-deposition process was done in the ionic liquid 1-butyl-1-methylpyrrolidinium trifluoromethylsulfonate, [Py1,4]TfO. A solution of (0.2 M FeCl2 + 2.75 M AlCl3)/ [Py1,4] TfO was used at a temperature of T=363 K because this mixture is solid at room temperature. Electrodeposited samples were studied by means of mechanical spectroscopy, differential thermal analysis and laser light microscopy. Mechanical spectroscopy studies were performed as a function of temperature, frequency and strain. The usual damping peaks for copper, low temperature grain boundary peak, recovery peak and intermediate temperature grain boundary peak were observed. In addition, a new damping peak at around 800 K which is not thermally activated was discovered. The physical mechanism controlling the appearance of this new peak is the dissolution of small precipitates or agglomerates of defects which take place at around 800 K during the warming and the subsequent re-precipitation/re-agglomeration during the cooling. This process could occur either in the copper substrate or at the Fe-Al electrodeposit.
  • Hot Pressing of Electrospun PVdF-CTFE Membranes as Separators for Lithium Batteries: a Delicate Balance Between Mechanical Properties and Retention Articles

    Trequattrini, Francesco; Palumbo, Oriele; Vitucci, Francesco Maria; Miriametro, Antonio; Croce, Fausto; Paolone, Annalisa

    Resumo em Inglês:

    A systematic investigation of the effect of hot-pressing on polyvinylidene fluoride (PVdF) - chlorotrifluoroethylene (CTFE) electrospun membranes, intended as separators and substrate for the electrolyte of lithium batteries, has been carried out by means of dynamic mechanical analysis. Absorption and desorption gravimetric measurements and infrared spectroscopy have been also performed. In particular, the mechanical properties of the membranes have been measured as a function of hot pressing temperature and pressure in the range 20 - 120 °C and 0 - 4 kbar, finding an increase of about 30 times of the tensile modulus after pressing at the highest temperature and pressure. Moreover, the conductivity of hot pressed membranes swelled by an ionic liquid measured as a function of temperature between - 60 and + 70 °C practically superimposes on that of the unpressed membrane.
  • The Contribution of Mechanical Spectroscopy to Understanding Grain Boundary Sliding Articles

    Mari, Daniele

    Resumo em Inglês:

    This review paper shows that grain boundary sliding (GBS) is a general phenomenon occurring in all classes of inorganic materials: ceramics, metals and composite materials. The occurrence of relaxations attributed to GBS is also quite general and therefore the mechanical spectroscopy constitutes a sensitive and universal technique to study such phenomenon. GBS is widely observed in ceramics. It can be due to the presence of an amorphous layer between the grains as in zirconia or to dislocations, as in alumina. In each case, a high temperature GBS peak has been identified. In metals, GBS is observed in some deformed materials but the correlation of such phenomenon with internal friction peaks has been controversial. In 1941, C. Zener describes a geometrical model of GBS that could give rise to a relaxation mechanism. In 1947, Kê observed a large relaxation peak in polycrystalline aluminum. This peak being absent in single crystals, the relaxation was attributed to GBS. Today, the Zener model can still be used in most cases for relaxations occurring in the grain boundaries. Instead, according to the grain boundary type, the material or the temperature, either dislocations or the gliding of a disordered layer produce the grain boundary relaxations.
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