摘要:

It is shown how Laue x‐ray diffraction patterns reveal crystal symmetry and Brillouin zone structure, which can be related to the energy ellipsoid structure derived from galvanomagnetic measurements. Numerical agreement is found between the angles of tilt of the energy ellipsoids from galvanomagnetic data and the angles of tilt of zone faces from x‐ray crystallography data.

ISSN:0021-8979    

DOI:10.1063/1.1729264

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

An etch‐pitting technique is described for revealing the points of intersection of dislocations with the (100) and (001) surfaces of calcium tungstate single crystals; each etch pit represents one dislocation. The dislocation configuration that is responsible for the residual strain in as‐grown ``a'' axis crystals and the mechanism of its growth from the melt are discussed. Preliminary results concerning the distribution of impurities in doped calcium tungstate crystals and the effect of doping on dislocation density and distribution are described. The solution behavior of calcium tungstate in various solvents and a chemical polishing procedure for calcium tungstate are presented.

ISSN:0021-8979    

DOI:10.1063/1.1729265

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

An analysis is presented of the stress field of a dislocation over the central plane of an infinite anisotropic plate with the dislocation lying in the plane. Basic expressions for such a field are given. The stress decreases monotonically as the thickness of the plate decreases. Thus, as expected, the internal stress field in the plate is weaker than in the bulk material for both isotropic and anisotropic cases. Anisotropy may either enhance or reduce the effect of thinning on the relative strength of the stress field (&sgr;/&sgr;inf., where &sgr;inf.is the stress in the infinite medium) when compared to the isotropic case. Criteria for differentiating the two opposite effects are presented.

ISSN:0021-8979    

DOI:10.1063/1.1729266

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

The minimum rate of entropy production, during the one‐dimensional freezing of a lamellar eutectic at velocityVhas been calculated using a well‐defined model. This principle is found to be equivalent to the maximum interface temperature principle at smallVbut not at largeV. Since it does not provide the correct relationship between lamellar spacing and freezing velocity over the entire experimental range, there is considerable doubt as to its physical significance when applied to this case.

ISSN:0021-8979    

DOI:10.1063/1.1729267

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

A Kerr magneto‐optic apparatus has been used to observe the effects of tensile stress on the domain structure in grain‐oriented 3.25% silicon steel. Unlike the powder pattern technique, the Kerr apparatus reveals the complete surface domain structure without regard to the type of domain wall, and enables observation of the domain structure changes upon application of small stresses. The behavior under stress of a new pattern, termed the ``chevron,'' has been noted.

ISSN:0021-8979    

DOI:10.1063/1.1729268

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

The conventional pyrometric measurement of wall, electrode, and probe temperatures through an alkali‐vapor atmosphere (which is, in part, cooler than the surface) has been found to lead to significant under‐estimation of the temperature. The error arises from optical absorption of the alkali‐vapor dimers in the region of the pyrometer passband. As an example, the observation through 6 cm of saturated potassium vapor of a surface whose brightness temperature is 2500°K results in an error of from 50° to 500°K as the vapor temperature varies from 300° to 370°C. Thus, substantial errors may be introduced into the determination of properties such as electrical conductivities and reaction rates, which are exponentially dependent upon temperature. The reciprocal‐temperature error was found to be roughly proportional to the dimer optical depth, and agreed with theoretical predictions utilizing dimer optical absorption coefficients measured during these experiments.

ISSN:0021-8979    

DOI:10.1063/1.1729269

出版商:AIP    

年代:1963

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1729271

出版商:AIP    

年代:1963

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1729272

出版商:AIP    

年代:1963

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1729273

出版商:AIP    

年代:1963

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1729275

出版商:AIP    

年代:1963

数据来源: AIP