金属热膨胀系数和键能
热膨胀系数是金属材料最重要的基本性质之一. 研究金属热膨胀系数的规律性对选择和使用合适的金属材料,在理论上和实践中都有很大的意义. 金属热膨胀系数的规律性,前人曾有不少研究<sup>[1-5]</sup>. 如Carnelley<sup>[1]</sup>早就指出熔点高的材料具有较小的热膨胀系数而熔点低的金属具有较大的热膨胀系数. 后来Hidnert和Sonder<sup>[2]</sup>把这个关系表达成下列经验公式:
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A numerical analysis of edge dislocation climb
The problem of diffusion controlled edge dislocation climb in a cylinder subjected to a biaxial stress state is solved using a finite element method of numerical analysis. The elastic interaction between the vacancy and the dislocation, which depends on both the r and θ coordinates about the dislocation, is included i…
Irradiation Effects on the Behavior of Structural Materials at Elevated Temperature
The paper provides a qualitative review of the effects of fast neutron irradiation on the mechanical behavior of materials used in the construction of Fast Breeder Reactor Core Components. The paper is presented in three sections. First, effects of preirradiation on the strength, ductility, elastic moduli, thermal cre…
On the Shake-up Satellite of Co2p in SrCoO3-x
X-ray photoelectron spectra for the perovskite-type oxides SrCoO 3- x ( x =0.5, 0.25, 0.03) were measured to observe the electron shake-up satellites in Co2p levels. The satellites are considered to be caused by the charge transfer from O2p σ to Co3d e g . Based on the one-electron model, the energy difference between…
Diffraction by two parallel slits in a plane
The diffraction of scalar waves by two parallel slits in a plane screen is examined by a method which uses orthogonal functions and Fourier transformations. A solution is obtained in the case of a perfectly soft screen. Numerical results of the plane wave transmission coefficients for normal incidence are given for k=…
TiO band strengths in metal-rich globular clusters
Observations are reported of the run of TiO band strength (7120 A) with effective temperature for stars at the tip of the giant branch in globular clusters. At temperatures for which the band is strong in field giants, TiO is undetected in clusters of intermediate metallicity. For this result reddening corrections are…
Rocket measurement of thermospheric photoelectron energy spectra
Relative values of thermospheric photoelectron energy distributions between 2 and 100 eV were measured over the altitude range 100–220 km by using a 127° cylindrical electrostatic deflection analyzer flown on a rocket. The measured photoelectron spectra display distinct features that are theoretically predicted (Victo…
Magnetic Transition of Orthoferrites with Compositions YFe1-xMnxO3
The spin configuration was studied by means of magnetic torque measurements on single crystals of manganese substituted orthoferrites, YFe 1- x Mn x O 3 where 0≤ x ≤0.55, at temperatures between 77 K and 450 K. Spin reorientations were observed in the samples containing more than x =0.1. It was concluded that the anti…
The Effect of Ply Lay-Up Sequence on the Fracture Toughness of Boron Aluminum
The fracture toughness of 0/90° cross ply boron reinforced aluminum composites has been investigated using prenotched compact tension and center notched tensile specimens. The effects on fracture toughness of specimen geometry, the relative numbers of 0° and 90° plys, and the lay-up sequence, have been measured. Ply l…
14—THE WET-RELAXED DIMENSIONS OF PLAIN-KNITTED FABRICS
Various states of relaxation of the plain weft-knitted structure are discussed in relation to fabric dimensions. An experimental investigation of dimensions in the wet-relaxed state shows that, in addition lo being dependent on the stitch length, these are also a function of the yarn diameter. A discussion of the poss…
ε-In2S3, eine Hochdruckmodifikation mit Korundstruktur / ε-In2S3, a High Pressure Modification with Corundum Type Structure
Abstract A quenchable high pressure modification of In 2 S 3 was prepared at 35kbar and 500 °C. ε-In 2 S 3 (Space group R3̅c, a = 656,1 pm, c = 1757.0 pm, Z = 6) is isotypic with Lu 2 S 3 (Corundum type structure).
Mechanism of Polyvinyl Chloride) Stabilization by Studies with Model Compounds
4-Chloro-2-hexene can be considered a model compound for the chlorinated allylic structure appearing in PVC chains after dehydrochlorination. This model compound was used to elucidate the mechanism of reaction of primary or secondary stabilizers.
THE FUNCTION OF THE PALLIAL ORGANS OF BIVALVES IN CONTROLLING INGESTION
THE FUNCTION OF THE PALLIAL ORGANS OF BIVALVES IN CONTROLLING INGESTION Get access Journal of Molluscan Studies, Volume 44, Issue 1, April 1978, Pages 83–99, https://doi.org/10.1093/oxfordjournals.mollus.a065419 Published: 01 April 1978 Article history Received: 13 April 1977 Published: 01 April 1978
Spin relaxation and magnetic shielding of93Nb nuclei in [NbClnBr6-n]-anions
The temperature dependence of T 1 and T 2 relaxation times of 93Nb nuclei in octahedral [NbCl n Br6-n ]-(n = 0 to 6) complexes contained in acetonitrile solution is measured. The relaxation rate is found to be controlled by quadrupole interactions in all complexes except cis-[NbCl3Br3]-. The relaxation mechanism in ci…
The Late Messinian Mediterranean Brackish to Freshwater Environment, Diatom Floral Evidence
Uppermost Messinian dolomitic mudstone with intercalated biogenic siliceous ooze in both Sites 124 (today at a water depth of 2726 m) and Site 374 (today at a water depth of 4090 m) contain a low diversified, autochthonous, almost monospecific, brackish, planktonic diatom assemblage, indicating a salinity range from O…
Differential Scanning Calorimetric study of the Kaolinite: N-Methylformamide Intercalate
Abstract The thermal decomposition of the kaolinite: N -methylformamide intercalate [Al 2 Si 2 O 5 (OH) 4 ·HCONHCH 3 ] has been studied by differential scanning calorimetry (DSC). The decomposition starts at 355 K, finishes at 450 K and follows Avrami-Erofeev kinetics for α = 0.04–0.96. Δ H for the loss of organic is…
13—THE BIAXIAL LOAD-EXTENSION BEHAVIOUR OF A MODEL OF PLAIN WEFT-KNITTING—PART I
An analysis is presented of a model of plain weft-knitting subjected to uniaxial loading in either direction and also to biaxial loading. For each case, calculated load–extension curves, which are given for a range of values of fabric tightness, illustrate biaxial fabric deformation. Each curve shows a marked dependen…
Stabilization of PVC by Organotin Compounds
Stabilizers, R2SnX2, react with allylic chlorine atoms during the induction period and also absorb HC1 to give XH molecules which add to double bonds. Changes in R which facilitate Sn-C bond cleavage are unfavorable, but γ-carbonyl groups are beneficial.
Intercalation of Salts in Halloysite
Abstract Several new salt intercalation complexes of halloysite have been prepared and characterized using X-ray powder diffraction techniques taking into account both the position and the shape of the d 001 peaks. The amount of intercalated ion in some fully complexed halloysites has been directly determined using co…
Magnetostriction of Fe–Ni Invar Alloys
Magnetostriction of fcc Fe–Ni alloys was measured by means of the paper strain gauge in the temperature range of 4.2 K to 296 K. The temperature dependence of spontaneous magnetostriction constant λ 111 was positive, while λ 100 was negative for all the alloys in the whole temperature range. The composition dependence…