Longitudinal Ultrasonic Velocity Research Articles

A note on the composition dependence of elastic properties of Se-P glasses

Longitudinal and shear wave ultrasonic velocities are reported in Se-P glasses over the composition range 0–50 at % P. The glass transition temperaturesT g show maxima at 30 and 50 at % of P, in consonance with earlier data. The bulk modulus shows minima at these compositions, contrary to the expectation of maxima. These are discussed in relation to the formation of compounds at specific compositions and the nature of the covalent bonding in the glasses.

Equation of state and melting properties ofHe4from measurements to 20 kbar

We measured simultaneously the pressure, volume, temperature, and ultrasonic longitudinal velocity in fluid $^{4}\mathrm{He}$ from 75 to 300 K and 2 to 20 kbar. The data were fitted to a Benedict-type equation of state from which various thermodynamic quantities were calculated. From 75 to 97 K the measurements extended into the solid region, yielding values of the melting properties and new constants for the Simon melting equation. We used the Lindemann relation to determine a Debye temperature from which the ultrasonic transverse velocity of solid. $^{4}\mathrm{He}$ was estimated. The melting entropy was analyzed to determine the contribution due to disordering of the atoms.

Elastic-constant variability in stainless-steel 304

Variability of elastic constants in stainless-steel 304 was determined by measuring longitudinal and transverse ultrasonic velocities in 20 samples acquired randomly. Three kinds of variations—sample to sample, directional within a sample, and repeated measurements on a single sample—are reported for four elastic constants: the bulk modulus, Young’s modulus, shear modulus, and Poisson’s ratio. Because of surprisingly small variations, 1% or less, the principal problem became measurement sensitivity and reproducibility. To overcome this problem, a high-resolution measurement system was devised using general-purpose equipment augmented with a very simple impedance-transforming amplifier and an FET transmission gate. With this system the often-reported troublesome transit-time correction disappeared. Effects due to frequency and directionality were negligible.

Sound velocity anomalies near the spin glass transition in an austenitic stainless steel alloy

Abstract A cusp in the magnetic susceptibility temperature dependence of a commercial manganese austenitic stainless steel alloy, attributable to spin-glass condensation, is accompanied by anomalies in the temperature dependences of both longitudinal and transverse ultrasonic wave velocities.

Elastic Behavior of Polycrystalline BaVS3 in the Temperature Range 40 K to 350 K

The longitudinal and transverse ultrasonic wave velocities of polycrystalline BaVS3 have been measured over a temperature range 40 K to 350 K. At 258 K the material undergoes a structural phase transition from a hexagonal to an orthorhombic form. Although the displacement of ions which occurs at the transformation is not so large, marked changes in the sound velocities as well as enhanced sound attenuation are observed at the transition. By analogy with the case of other perovskite-like compounds, the present observations are qualitatively explained by considering the interaction of “soft-mode” phonons with the elastic distortions produced by the phase transition.

Low-temperature elastic properties of a 300-grade maraging steel

Elastic properties of an annealed 300-grade maraging steel (18 Ni, 9 Co, 5 Mo pct by weight) were studied between room temperature and liquid-helium temperature. Longi-tudinal and transverse ultrasonic velocities were determined by a pulse method. The re-ported elastic constants are: longitudinal modulus, shear modulus, Young’s modulus, bulk modulus, and Poisson’s ratio. Except for the bulk modulus, the room-temperature elas-tic constants are all lower than those of iron; and their temperature dependencies are regular in the studied temperature region.

Reshock and release of shock-compressed 6061-T6 aluminum

The release and reshock behavior of aluminum from an initial shock stress of 2 GPa (20 kbar) has been examined. It is found that a two-wave structure characterizes both release and recompression, although a definite elastic-plastic structure is not obtained in either case. The velocity of the initial disturbance for both recompression and release agrees with the extrapolated ultrasonic longitudinal velocity, which implies initial elastic response from the precompressed state. The present results are discussed in terms of a rate-independent model which incorporates a distribution of yield states in the precompressed material. Reasonable agreement with experimental reshock and release wave profiles is obtained with this model. A brief discussion of rate effects estimated from an acceleration wave analysis is also presented.

Measurements of longitudinal and transverse ultrasonic wave velocities in compressed solidified argon and their relationship to melting theory

Measurements of longitudinal and transverse ultrasonic wave velocities have been made on compressed, solidified argon for pressures up to 6 kbar (600 MPa) corresponding to melting temperatures in the range 123–206 K. Velocities in the solid phase were measured along isochores to within ∼10−3 K of the melting line. The Lindemann melting parameter, obtained from appropriate physical quantities at the melting line, was constant within the limits of error of the measurement (±2%).

The elastic properties of hard tissues and apatites.

AbstractThe pressure dependence of the elastic constants of various halides, hard tissues and synthetic apatites have been examined in the 0‐ to 50‐kilobar range using a solid media, pressure apparatus coupled with an ultrasonic interferometer. The samples includ: hydroxy‐, fluor‐, and chlor‐apatite, NaCl, CaF2, mollusc shell (aragonite), ivory, dentin and enamel, and fish, bovine, and human bones. High pressures were used in order to assess the effects of porosity in aggregate samples and to make measurements on specimens of ideal density. Computer analysis of the measured longitudinal and shear ultrasonic velocities yields the pressure dependence of the bulk, shear, and Young's moduli and Poisson's ratio. Atmospheric pressure values at ideal density are obtained by back extrapolation from the high pressure measurements.

ULTRASONIC OBSERVATION OF CALCITE I-II INVERSION TO 700°C

The phase boundary for calcite I-II inversion was determined on the P-T plane up to 700°C and 25kb. The change in longitudinal ultrasonic velocity, which shows a remarkable minimum at the inversion point, was measured. The slope of the phase boundary is negative up to about 250°C; this coincides with the results of P.W. Bridgman and C. Wang. Above 300°C, the slope of the boundary turns to positive, and the inversion pressure rapidly rises with increasing temperature. The boundary has a minimum pressure at about 250°C. Since the boundary of calcite I and calcite II will never cross the boundary of calcite I and aragonite, there is no stable region for calcite II.

Elastic constants of solid krypton

The adiabatic elastic constants c 11 and c 44 of solid Kr could be determined from measurements of the longitudinal and transverse ultrasonic velocities in the temperature range from 110 K to 4.2 K. c 12 has been calculated from c 11 and from the experimental values of the isothermal compressibility, the thermal expansion coefficient, the molare volume and the isobaric specific heat.

The pressure dependence of the elastic constants of dental amalgam.

AbstractThe pressure dependence of the elastic constants of dental amalgam has been examined in the 0–50 kilobar range using a solid media, pressure apparatus coupled with an ultrasonic interferometer. Computer analysis of the measured longitudinal and shear ultrasonic wave velocities yields the pressure dependence of the bulk, shear and Young's moduli and Poisson's ratio. Samples were prepared with varying compositions from micro‐cut and spherical dental alloys. The elastic behavior of these samples can be directly related to the sample structure and composition as well as to the manipulation during preparation. In addition, an estimate can be made of the volume concentration of porosity.

Non-Destructive Evaluation of Green Ceramic Body Density by Ultrasonic Technique

Laboratory measurements of spatial density distribution in green ceramic tiles were implemented using ultrasonic contact coupling measurement method. The main objective of these measurements is to measure spatial density distribution in pressed green ceramic tiles. Measurements of longitudinal ultrasonic wave propagation velocity were carried out using pulse and correlation methods and the tile density values were calculated. Evaluation of the measurement method, estimation of uncertainty of measurements and analysis of further improvements purposed to adapt it for on-line measurements in a production process were carried out. Ill. 7, bibl. 16, tabl. 1 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.111.5.360

Ultrasonic Relaxation in a Simple Organic Glass

Ultrasonic longitudinal absorption and velocity measurements were made in the glass-forming ionic liquid substance Galex. Galex, a low-molecular-weight wood rosin, is composed largely of dehydroabietic acid. The viscosity of this substance above and below the melting point has an Arrhenius temperature dependence, but the slope of the log η vs 1/T changes near the melting point. The results of ultrasonic measurements on both sides of the viscosity discontinuity indicate the existence of a relaxation region in both the glass and liquid. In both cases, the relaxation process is fully accounted for by a single relaxation time. Analysis of the data shows that in the glass region (low-temperature side of the viscosity discontinuity), structure rearrangement is responsible for the observed excess absorption, while in the liquid region, the relaxation process is thermal in nature.

Wave velocities and hysteresis in Solenhofen limestone for pressures up to 12 kilobars

Precision shear (S) and longitudinal (P) ultrasonic velocity measurements were made on jacketed and unjacketed Solenhofen limestone as a function of hydrostatic pressure to 12 kb. Measurements of P velocities were also made in the C direction of calcite to 12 kb and in fused quartz to 14 kb. For constant pressure below approximately 5 kb the P and S velocities in jacketed Solenhofen limestone are found to be directly proportional to initial specimen density. After subjecting specimens to pressures greater than 5 kb, they exhibit features attributed to the polycrystalline nature and porosity of the limestone: (1) a permanent decrease in the zero-pressure velocity is observed which is explained by microfractures at regions of high stress concentration, (2) a ‘negative velocity hysteresis’ is observed; i.e., velocities measured with increasing pressure are less than the velocities measured with decreasing pressure; this feature can be explained on the basis of either phase transitions or porosity changes accompanying permanent deformations. Unjacketed Solenhofen limestone exhibited a ‘positive velocity hysteresis’ that can be explained on the basis of trapped fluid in the pores. The P and S velocities for jacketed Solenhofen limestone falls sharply at pressures exceeding about 8 kb. Comparison with data of unjacketed specimens provides experimental evidence that the often observed sharp decrease in the velocity occurring below 15 kb is a result of local stress concentrations in the specimen.

Shear and Structural Relaxation in Molten Zinc Chloride

Longitudinal ultrasonic absorption and velocity measurements were made in molten zinc chloride in the frequency range 5–95 Mc/sec. Shear relaxation measurements were obtained in the frequency range 43–118 Mc/sec. A single relaxation time was observed for the absorption of longitudinal waves at each temperature investigated. The absorption data demonstrated the existence of a volume viscosity which was found attributable to a structural single-relaxation mechanism. Shear and structural relaxations were both present with the same single relaxation time. The activation energies for the shear and compressional flows are approximately equal. The variation of the relaxation time with temperature is in accordance with the rate theory. The shear modulus and the relaxational part of the compressional modulus increase exponentially with decreasing temperature. The temperature dependence of the former is predicted by the two-state model of the hole theory. From numerous physical properties of molten zinc chloride and from the known crystalline state, a structural model is proposed for the melt. Two points are emphasized: (1) that there exist large ion complexes and (2) that there is a lack of network character in liquid ZnCl2. Based on this model, an explanation of the existence of distribution of relaxation times, observed in the glass-forming network liquids, is offered which attributes the presence of a whole spectrum of relaxation times in these liquids to the cooperative nature of their flow process. The measured single relaxation time of molten zinc chloride owes its origin to its nonnetwork character.

Improved Methods for Measuring Ultrasonic Velocity

Some improved sound wave interference methods for measuring the longitudinal and transverse ultrasonic velocity in opaque as well as transparent solids may be simply carried out by using the ultrasonic light-diffraction system (as arranged for making sound beams visible on a screen). The sonic unit of the system is arranged to produce two individual traveling-wave sound beams, by use of two generators by splitting a single beam. Three simple arrangements are described in detail. In Case A one beam travels entirely in a reference liquid, while the other beam travels a parallel path in an immersed transparent test specimen. In Case B one beam travels entirely in a reference liquid, while the other beam travels an adjacent course through an immersed, transparent or opaque test prism, and on into the liquid at an angle to the first beam. In Case C the two beams are generated at the equal edge faces of a transparent or opaque isosceles test prism (only the base edge face contacting the liquid). The two beams traverse the prism to the base, where they are refracted into the test liquid as confluent beams. In Cases A and B, simulated interference (by optical integration), and in Case C true interference, each give a light and dark band interference pattern on the screen, whose band spacing is used in calculating the velocity of sound in the test solid. The other required factors are the optical image magnification, the frequency of the sound, the angular disposition of the one or more acoustic surfaces of the test solid relative to the incident sound beams, and in Cases A and B the velocity of sound in the reference medium. Other variations of arrangement are suggested. Advantages of the improved methods are simple preparation of test specimen, directness and simplicity of measurement and calculation, good accuracy, low sonic power requirements. A table of measured velocities (and attenuations) in two metals and in numerous plastics and polymers show the wide range of materials that may be measured by the new interference methods.