Temperature dependence of Weibull stress parameters: Studies using the Euro-material

This work demonstrates the temperature invariance of the Weibull stress modulus, m, for a 22Ni-MoCr37 pressure vessel steel through calibrations at two extreme temperatures of the ductile-to-brittle transition. This temperature invariance reflects the characterization of microcrack size distribution in the material described by the modulus. The calibrations performed here also demonstrate the clear dependence of the Weibull scale parameter, σ_u, on temperature. The increase of σ_u with temperature reflects the increase in microscale toughness of ferritic steels. The calibration procedure employs a three-parameter Weibull stress model which includes the effects of a minimum (threshold) toughness, K_min. The calibrations suggest that K_min increases gradually with temperature. Finally, an engineering procedure is presented to enable practical applications of the Weibull stress model for defect assessments. This procedure combines the demonstrated temperature invariance of m, a recently developed method for predicting the variation of σ_u with temperature using the Master Curve, and calibration of the Weibull stress parameters at one temperature. The (calibrated) temperature invariant m and the estimated σ_u as a function of temperature are used to predict the cumulative probability of fracture for several large datasets without direct calibration.     

Temperature dependence of the dielectric parameters of thin arsenic triselenide layers with high bismuth content

The temperature and frequency dependences of the dielectric parameters (dielectric permittivity and loss tangent) of modified arsenic triselenide layers with high bismuth content have been studied. In the infralow frequency range, an increase in the temperature leads to significant growth of the real component of the complex permittivity and the appearance of maxima in the dielectric loss tangent. At greater frequencies, these maxima shift toward higher temperatures.     

Temperature dependence of microelectronic device failures

Recently, the use and the applicability of reliability prediction models for microelectronic devices using the temperature-dependent Eyring and Arrhenius function, have been criticized. In fact, the temperature dependence of failure mechanisms of microelectronic devices and electronic equipment in general has been questioned. This paper discusses the effect of temperature on microelectronic failure mechanisms at various device failure sites. This paper also presents information on those mechanisms which may be more appropriately modelled by functions dependent on temperature change, the rate of temperature change and spatial temperature gradients.     

Temperature dependence of polymer film emissivity

The effect of heating upon transparency and emissivity of polymer films is studied.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 37, No. 2, pp. 285–288, August, 1979.     

Temperature dependence of the band gap, refractive index and single-oscillator parameters of amorphous indium selenide thin films

InSe thin films are obtained by evaporating InSe crystal onto ultrasonically cleaned glass substrates under pressure of 10⁻⁵ Torr. The structural and compositional analysis revealed that these films are of amorphous nature and are atomically composed of 51% In and 49% Se. The reflectance and transmittance of the films are measured at various temperatures (300–450 K) in the incident photon energy range of 1.1–2.1 eV. The direct allowed transitions band gap – calculated at various temperatures – show a linear dependence on temperature. The absolute zero value band gap and the rate of change of the band gap with temperature are found to be (1.62 ± 0.01) eV and −(4.27 ± 0.02) × 10⁻⁴ eV/K, respectively. The room temperature refractive index is estimated from the transmittance spectrum. The later analysis allowed the identification of the static refractive index, static dielectric constant, oscillator strength and oscillator energy.     

Temperature dependence of the birefringence of SiC

Measurements of the birefringence of 6H-SiC, as well as its temperature dependence, are presented. The results are used to explore the possibilities this material presents as a mid-infrared non-linear optical parametric oscillator.     

Temperature dependence of thermal conductivity of helium

Experimental data for the thermal conductivity of helium are generalized. A computational equation is proposed.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 32, No. 5, pp. 822–824, May, 1977.     

Temperature dependence of capacitance on DNA solutions

We have measured the temperature dependence of the capacitance on the poly(dA), poly(dA)–poly(dT), and DNA solutions with both A–T and G–C base pairs to investigate the relation between the capacitance and the DNA structure. As the temperature increases, the capacitance of the single-stranded DNA solution increases, whereas that of the double-stranded one decreases with increasing the temperature and exhibits an upturn when DNA molecules are denatured. Moreover, the temperature dependence of the capacitance is found to be different depending on the DNA sequence. These results suggest that the conformational change of DNA molecules can be detected through the capacitance measurements that do not require any labeling and immobilization on a solid support.     

Temperature dependence of microhardness in mixed crystals

The temperature dependence of microhardness of mixed KCl-KBr crystals has been studied using the Kataoka and Yamada theory which considers plastic deformation and internal stress field due to elastic interactions in mixed crystals. The microhardness showed systematic variation with temperature in both the components and the mixed crystals and the probable reasons for this variation are indicated.     

Temperature dependence of ferrobielastic switching in quartz

Using the piezoelectric effect, the variation of coercive stress with temperature for ferrobielastic switching in synthetic quartz crystals has been measured under unaxial load applied in a direction favoring Dauphiné twinning. It is found that the coercive stress decreases with increasing temperature from about 4×10⁸ Pa at room temperature to less than 10⁷ Pa near 300°C.     

Temperature dependence of mechanical characteristics of wheel steels

We investigate the influence of high temperatures (to 800°C) on the mechanical characteristics of medium- and high-strength wheel steels. It is shown that the lower the austenization temperature and the sharper the increase in the plasticity, which is caused by the dissolution of vanadium carbides and carbonitrides in a high-strength steel, the more favorable the conditions of formation of flat-type defects on the rolling surface of high-strength wheels (of KP-T type) against those for medium-strength wheels (of KP-2 type).     

Temperature dependence of the birefringence of optical-disk substrates

Injection-molded polycarbonate substrates are used predominantly in read-only, write-once, phase-change and magneto-optic disks for data storage. The in-plane and vertical birefringences of these substrates adversely affect the performance of optical data-storage systems. The disks are typically expected to operate in the ambient temperature range of 5-50 °C. We have investigated the behavior of the in-plane and vertical birefringences of a polycarbonate disk substrate in this temperature range using a custom-built ellipsometer. This study reveals that the in-plane birefringence changes dramatically within the investigated range of temperatures, whereas the vertical birefringence remains essentially constant. We suspect that the change in birefringence is due primarily to thermally induced stress in the substrate.     

Temperature dependence of the density of liquid tin

The two-capillary pycnometer method is used to study the temperature dependence of the density of tin in the temperature range fromT _melt to 770 K. The measurements are carried out in a superhigh vacuum in higher purity samples. The experimental data are described by an equation of the straight line p(T) = 7374.7 -676.5 x 10_-3Trand do not confirm the anomaly (observed previously by some authors) in the form of a minimum on the poly therm of the density of tin in the temperature range from 610 to 700 K