摘要:

By large scale modification of established whisker growing techniques, it was possible to produce single crystals of alpha iron between 1 and 2 mm in diameter and up to 80 mm in length. These crystals grew along a ⟨100⟩ axis and had {100} faces. The final size of the crystals appeared to depend upon the quantity of FeCl2vapor available for reduction. Some growth features are reported.

ISSN:0021-8979    

DOI:10.1063/1.1728249

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

Data are presented to show that plastic deformation by torsion occuring at temperatures between 700° and 800°C enhance self‐diffusion in silver single crystals. The enhancement varies linearly with surface strain rate, is larger the lower the temperature and is independent of surface strain. The results of experiments at constant stress are discussed in relation to ideas developed by Weertmann. The lifetime of point defects (assumed to be vacancies) at 800°C has been measured as about 100 sec. This permitted the calculation of the concentration of vacancies produced per unit strain.

ISSN:0021-8979    

DOI:10.1063/1.1728250

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

The differential thermal analysis (DTA) technique is used to measure the Curie temperature of yttrium iron garnets, and of the garnets obtained by partially substituting Sm, Nd, Pr, or La for the Y. The accuracy of the method is within about 1°C. It is found that in all the above substitutions the Curie point is increased more or less linearily in the rare‐earth contents, with the largest slope for Pr, somewhat less for Nd and Sm. For La, only the compound Y2.5La0.5Fe5O12could be prepared and it did not show any measurable change from the Curie point of pure yttrium iron garnet. Two possible explanation are suggested to the increase in Curie point by Sm substitution, which does not change the magnetization of the garnet.

ISSN:0021-8979    

DOI:10.1063/1.1728251

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

Electron spin resonance characteristics of a number of materials subjected to violent mechanical treatment are reported. A line withg=2.0055 observed in silicon is attributed to defects introduced near the surface by mechanical damage. The resonance properties are uninfluenced by interactions of the silicon surface with atmospheric gases. Similar lines appear in germanium, silicon carbide, and diamond. The dominant line produced by mechanical damage to MgO is attributed toFcenters. Similar lines are observed in other II‐VI compounds. Results are also reported for a number of other materials. Similarity between defects produced mechanically and by fast neutrons is noted.

ISSN:0021-8979    

DOI:10.1063/1.1728252

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

The dislocation damping theory of Koehler, Granato, and Lu¨cke is modified for metals with high stacking fault energy. It is assumed that the most abundant impurity atom species interacts only with the edge component of each dislocation. For this model the hysteretic, or frequency independent damping initially increases linearly with stress amplitude and approaches the Granato‐Lu¨cke amplitude dependence at higher stresses. The influence of a second, less abundant impurity atom species which can interact withbothscrew and edge components also is considered. When the glide distance of a dislocation after breakaway becomes comparable with the mean spacing of the second type of impurity, the hysteretic damping becomes amplitude independent. This modification is best suited for application to the damping of bcc metals containing a higher concentration of substitutional impurities than interstitial impurities.

ISSN:0021-8979    

DOI:10.1063/1.1728253

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

An etch pit technique has been developed that reveals the sites of dislocations which intersect the basal plane surface of zinc crystals. Pits can be formed by either Cl2, HCl, Br2, HBr, or HI dissolved in an appropriate organic solvent. Etchants made with Cl2or HCl produce hexagonal pyramidal pits whose edges are parallel to ⟨101¯0⟩ directions; but Br2, BHr, or HI etchants produce hexagonal pits whose edges are parallel to ⟨112¯0⟩ directions. The technique is useful for observing glide which occurs on nonbasal planes. The dislocation etch pits are seen to form a ``polygonization'' pattern in a crystal that was annealed after deformation. A discussion is presented on the mechanism of etch pit formation and the factors which might determine the shape of the pits.

ISSN:0021-8979    

DOI:10.1063/1.1728254

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

The strain energy of a crossed grid of screw dislocations is calculated using isotropic elasticity theory. It is found that a distortion from the stable structure requires a large amount of strain energy. It is indicated that long‐range stresses can exist in metastable dislocation networks without a long pile‐up of like dislocations. Possible rearrangements of dislocation networks in both fcc and bcc metals are shown.

ISSN:0021-8979    

DOI:10.1063/1.1728255

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

The stress introduced by solute lattice contraction of boron and phosphorus in silicon is shown to be sufficient to generate dislocations in silicon wafers. Such dislocations were observed. Expressions for the density distribution and for the total number of dislocations generated are derived and a mechanism of dislocation generation and distribution during the diffusion process is postulated. The dislocation distribution is shown to be highly dependent upon the nature of the diffusion process, expressions being derived for the conditions of (1) constant surface concentration of solute and (2) diffusion from a finite source. An expression for and means to determine the residual stresses in diffused silicon wafers are given.

ISSN:0021-8979    

DOI:10.1063/1.1728256

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

The transition properties of thin superconducting tin films are determined through measurements on a new device, the superconductive radio‐frequency mixer. An equivalent circuit for this device is presented which permits the prediction of mixer performance using static transmission curves for the particular films employed. Experimental transmission curves and their characteristics are discussed. The measured mixer performance is compared with theoretical performance for operation in the frequency range of 240 to 840 Mc. It is shown that the transition speed of the superconducting thin films can be determined and that film‐switching times are at least as short as 0.625 nsec.

ISSN:0021-8979    

DOI:10.1063/1.1728257

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

The rising of a dielectric liquid along high‐voltage electrodes that are dipped into it is investigated. Qualitative results are given for a number of different combinations of electrode material and liquid. The effects observed for molybdenum‐acetone systems, excited by low‐frequency applied voltage are discussed in detail.

ISSN:0021-8979    

DOI:10.1063/1.1728258

出版商:AIP    

年代:1961

数据来源: AIP