摘要:

The Li K and Mg L23spectra have been observed from a range of Li-Mg alloys, evidence for electron transfer from Mg being obtained. More distinct changes have been observed for the same spectra when Li was evaporated onto solid Mg and Mg onto solid Li. Changes in the Li K and Al L23were observed when Li was evaporated onto Al and in the Al L23when Al was evaporated onto Mg. No changes greater than 5 × 10−2ev were observed in edge wavelengths or edge widths although marked depopulation of higher energy states occurred in Mg and Al. It is inferred that changes in the screening of K and L levels compensate almost exactly for the effects of electron transfer. The results of Catterall and Trotter (1959) were confirmed in that the Mg band contracted and the Li band extended on the low-energy side. Li deposited on Al shows a K spectrum without any metal edge, suggesting that the first zone is filled and that there is no overlap with the second zone.

ISSN:0031-8086    

DOI:10.1080/14786436008238332

出版商:Taylor & Francis Group    

年代:1960

数据来源: Taylor

摘要:

Thin foils of 99–999% aluminium prepared by electropolishing have been found to develop surface pits along the grain boundaries during ageing at room temperature. It is suggested that the pits are formed by a vacancy mechanism, and that they are associated with the initiation of etch attack along the grain boundaries of aged pure aluminium.

ISSN:0031-8086    

DOI:10.1080/14786436008238333

出版商:Taylor & Francis Group    

年代:1960

数据来源: Taylor

摘要:

Etching of ice crystals grown from both the vapour and the melt has revealed etch pits in concentrations of up to 106/cm2which apparently mark the sites of emergent dislocations. Silvered Formvar replicas show the etch pits on the basal surface to be hexagonal pyramids on which spiral or closed terraces of steps are often visible. These features are interpreted in terms of the etching of helical dislocations. The etch pits tend to group themselves along low-angle grain boundaries and slip lines. When the crystal is mechanically stressed, etch channels appear on the basal plane along the ⟨1120⟩ directions which suggests that these are the preferred glide directions.

ISSN:0031-8086    

DOI:10.1080/14786436008238334

出版商:Taylor & Francis Group    

年代:1960

数据来源: Taylor

摘要:

Measurements have been made of the variations with temperature of the intensities of x-ray diffraction lines from silver and iron. For silver the measurements were in the range 286–1100°K, and the Debye-Waller temperature factor corresponded to a characteristic temperature of 197°K at 286°K. For iron the measurements covered the range 286–1190°K, and corresponded to θ = 389°K, although there was a large scatter in the results due to crystal changes brought about by annealing. The intensity measurements showed no discontinuity at the Curie temperature, nor was there any anomaly in the spacing of the (110) planes.

ISSN:0031-8086    

DOI:10.1080/14786436008238335

出版商:Taylor & Francis Group    

年代:1960

数据来源: Taylor

摘要:

In a crystalline element the scattering of long wavelength neutrons by a point defect and an atom are known to be identical. However, when lattice distortion around the point defect is also considered, this is no longer true; in particular the scattering of a point defect is now anisotropic and varies with wavelength. An expression for the cross section of a defect in a relaxed lattice has been derived and applied to f.c.c. and b.c.c. lattices, and in greater detail to copper and molybdenum where the magnitude of the relaxation around defects is known. It has been found that the scattering cross section is appreciably altered by the relaxation of the surrounding atoms, and in particular from those that are nearest neighbours to the defect. A neglect of this relaxation in the interpretation of a neutron scattering experiment could lead to an error of an order of magnitude in an estimate of the number of defects. Also a study of the variation in cross section with wavelength or scattering angle, which is analogous to an x-ray small angle scattering experiment, is incapable of determining uniquely the size of defect agglomerates in solids. However, under favourable circumstances, such experiments could become a useful technique for estimating the lattice distortion around defects.

ISSN:0031-8086    

DOI:10.1080/14786436008238336

出版商:Taylor & Francis Group    

年代:1960

数据来源: Taylor

摘要:

The electron microscope has been, used to examine point defect clusters produced in copper and aluminium foils bombarded with l·4 × 1017alpha-particles cm−2. The foils were bombarded as a stack and, in copper, both those through which the alpha-particles had passed and that in which they came to rest appeared similar, containing dislocation loops (r∼ 200 Å) and a background of more numerous and smaller dots (r∼20 Å). The behaviour at grain boundaries suggested that these two types of cluster were due to different point defects. Whereas the dislocation loops normally annealed out at about 350°c, in the foil in which the alpha-particles came to rest (containing ∼ 1015atoms of helium cm−2) they grew to form a dislocation tangle, and eventually small helium bubbles (r∼ 40 Å) appeared in the same number as the original small dots. These results indicate that the dislocation loops are due to the clustering ofinterstitial atomsand the small dots are clusters formed fromvacancies. It is also inferred that the helium atoms are in interstitial positions during the bombardment, and form bubbles by nucleating upon the dusters.

ISSN:0031-8086    

DOI:10.1080/14786436008238337

出版商:Taylor & Francis Group    

年代:1960

数据来源: Taylor

摘要:

Recent observations of the growth of quenched-in dislocation loops during annealing are discussed. A mechanism for the coalescence of loops is proposed. The mechanism depends on short-circuit diffusion around the periphery of prismatic dislocation loops. This mechanism is contrasted with the theory of loop coalescence by vacancy diffusion through the matrix. It is shown that the experimental observations are in better accord with the short-circuit diffusion theory.

ISSN:0031-8086    

DOI:10.1080/14786436008238338

出版商:Taylor & Francis Group    

年代:1960

数据来源: Taylor

摘要:

The magnetic susceptibilities of a number of solid solutions of chromium in vanadium have been measured at 20°, 77° and 293°K. The susceptibility at 20°K decreases with concentration from a value of 300 × 10−6e.m.u./g atom for pure vanadium to 159 × 10−6e.m.u./g atom for pure chromium. Fine structure is observed in several regions of the susceptibility-composition curve. The temperature dependence of the susceptibility of all the alloys investigated was small.

ISSN:0031-8086    

DOI:10.1080/14786436008238339

出版商:Taylor & Francis Group    

年代:1960

数据来源: Taylor

摘要:

The hyperfine structure (H.F.S.) of theJ= 3/2 ground state of209Bi has been found by the atomic beam magnetic resonance method. Two of the three H.F.S. intervals were measured directly, giving

ISSN:0031-8086    

DOI:10.1080/14786436008238340

出版商:Taylor & Francis Group    

年代:1960

数据来源: Taylor

摘要:

The hyperfine structure of theJ=3/2 ground state of121Sb and123Sb has been studied by the atomic beam magnetic resonance method, and the results are consistent with the following values for the interaction constants:

ISSN:0031-8086    

DOI:10.1080/14786436008238341

出版商:Taylor & Francis Group    

年代:1960

数据来源: Taylor