Umwandlungsplastizität und Form-Gedächtnis-Effekt in einer Eisenlegierung mit 16% Mangan

During the quenching of wire shaped specimens of steel X8Mn16 fec austenite changes under reduction of length in hcp ϵ-martensite. If the transformation takes place under the influence of an external tensile stress an elongation results. This transformation plasticity consists of a reversible and an irreversible part. The reversibel part rises by the formation of stress-induced ϵ-martensite in preferred orientation and is built back under reduction of length during the following heating over the Af-temperature. By this it is verified that the strain-memory-effect can occur in iron alloys too. A plastic deformation of the austenite below the recristallisation temperature prevents the γ → ϵ-transformation.     

Reaktivität von mechanisch aktiviertem Quarz

By grinding of quartz arises a strong disorder. In this amorphous range the centres of defectelectrons or the E'centres are concentrated. The amorphous range shows a changed reactivity.     

Kristallographische Polarität von AIIIBV - Mischkristallen

From the measurement of X-ray intensity differences of opposite {111}-surfaces in Ga₁ – _xAl_xAs- und Ga₁ – _xAl_xSb-mixed crystals with high Al concentration it was concluded which of the two surfaces is terminated by a layer of the group V atoms. The results are correlated with etching studies.     

Einfluß der Substruktur auf die optische Homogenität von Rubin-Laserstäben

The relation between mosaic structure and optical homogenity was measured of 90° ruby laser rod. The optical homogenity was measured by the interferometric method and the mosaic misorientation by Berg-Barrett method and the oscillation spectrometer respectively. The proportionality between the number of the interference stripes and the rotation of the mosaic blocks about an axis perpendicular to the growth axis and crystallographic c-axis was found.     

Einfluß der Temperung auf die optische Homogenität von Korund-Einkristallen

The influence of annealing corundum rods was investigated in controlling the number of interference stripes. Annealing at least of 1100-1200°C improves optical homogeneity of the perfect crystals. Annealing at 1900-1980°C only slightly improves optical homogeneity of rubies.     

Über den Zusammenhang zwischen Kompressibilität und Härte von Mineralen und nichtmetallischen kristallinen Substanzen

An attempt is made to find out an experimental correlation between diamond pyramid microhardness number HV (according to Vickers) and compressibility χ of nonmetallic intrusion substances. By means of thermoelastic considerations, especially with respect to diamond and related to the bonding theory of crystals, a logarithmic plot of χ (log HV) yields a group of straight χ-lines. Further, as a technical consequence, a computation formula is given for conversing Mohs' hardness test numbers to HV-numbers and vice versa.     

Erosivität und Mechanolumineszenz

One of the complicated properties of solids is also their erosivity. An exact and simple definition makes the erosivity as an easy measurable property of solids. The erosion which is the reason of erosivity has two aspects: 1. technological as an working procedure, 2. methodical as a method for the measuring of erosivity. Because with the erosion there are two objects in interaction, the abrasive particles and the material to be machined — with their collision deformations occurs. It is possible in some cases to observe mechanoluminescence. The mechanoluminescence can be used as to the interpretation of the erosionsmechanism as to the regulation of the experimental collisions.     

Orientierte Einlagerungen von Nonylphenolpolyglykoläthern in Zwischenschichträumen von Montmorillonitkristallen

Polyoxathylated nonylphenols were adsorbed by hydrogen bonding to oxygen-rich montmorillonite surfaces. These compounds were also held in the interlayer spaces of montmorillonite and tended to form mono- and double-layers. The kind of complexes and the orientation of molecules in the interlayer spaces are discussed.     

Präparation und Charakterisierung von Granateinkristalloberflächen

The preparation of single crystal substrates of gadolinium gallium garnet as a typical example of a brittle material is described. The mechanical polishing with iron oxide and diamond as well as a mechano-chemical polishing procedure basing on SiO₂/H₃PO₄ are investigated. Working damage is investigated by X-ray topography, double crystal spectrometry and selective etching. Results are discussed in the frame of a brittle fracture model of the abrasion process.     

Herstellung von Rubin-Saphir-Übergängen

A method for the preparation of ruby-saphire crystals is described. Some information on the optical behaviour of the transition are given.     

Oberflächenbeurteilung von bearbeiteten Siliziumscheiben

For the judgement of various polished surfaces of silicon single disks was used the method of reflexion high energy electron diffraction (RHEED) in the electron microscope and on the other hand the X-ray-method of double crystal spectrometry. Because of the obtained diffraction pictures and the obtained rocking curves and because of the completing figures of surfaces with the replica method on the electron microscope, it is possible to estimate the silicon single disks relating to the mistakes in the surface range.     

Struktur von AIIBVI-Epitaxieschichten in Abhängigkeit von den Aufdampfbedingungen

The structure of epitaxial films of A^IIB^VI-compounds is discussed. Especially the results of investigations concerning the epitaxy of CdSe on cleavage planes of NaCl and CaF₂ using high-vacuum evaporation are treated. Epitaxial films of A^IIB^VI-compounds usually show defect structures due to the co-existence of the zincblende and wurtzite structures, oriented overgrowth of these two phases, twinning and stacking faults. The resulting complex diffraction patterns (for electron diffraction in transmission) are discussed. The nature of the substrate, substrate temperature, and deposition rate besides experimental factors decisively influence the orientation, structure, and phase composition of the films. An influence of deviations from the stoichiometric composition has to be taken into account.     

Zur elastischen Wechselwirkung von Punktdefekten und Einschlüssen in der Nähe von Festkörperoberflächen

Calculating the interaction energy of point defects and inclusions in solids the influence of solid surfaces usually is neglected. But in the immediate vicinity of the boundary surfaces the deformations around the defects are, connected with a certain extra contribution to the total energy which was calculated applying continuum mechanics methods. The medium is assumed to be isotropic and homogeneous. An analytic expression for the interaction energy of two spherical inclusions near a half-room boundary surface is derived. The results show the interesting phenomenon that both attraction and repulsion between the defects occur, only depending upon the geometrical parameters.     

Über die Flächenverteilung von Dekorationskeimen in der Umgebung von Versetzungen

Cleaved and evaporated faces of KCl:Me²⁺ single crystals were decorated with gold. The surface distribution of the decoration grains was investigated electron-microscopically. In the surroundings of the points of emergence of dislocations characteristic changes in the density distribution of the gold grains could be observed. They are described and discussed.     

Gitterkonstantenänderungen und chemische Inhomogenitäten von tetragonalem ZnSiP2

X-ray lattice parameter measurements in small specimen volumes of ZnSiP₂ crystals by means of the Bond method demonstrate local chemical inhomogenities probably caused by changes in Si concentration up to about 0.8 atomic p.c.     

Untersuchungen zur Unstöchiometrie von Magnetit in Abhängigkeit von den Bildungsbedingungen

This paper reports on investigations on the chemical composition and structure of magnetite depending on the conditions of chemical reactions. Magnetites were prepared according to a method described by GIOVANOLI and BRÜTSCH which, originally, had been a means for the preparation of γ-FeOOH. — After investigations on lattice parameters and relation Fe²⁺:Fe³⁺ we found that the chemical composition and structure of magnetites is a function of the conditions under which reaction takes place. The composition of the reaction product more and more approaches the state of an ideal stoichiometric magnetite (Fe₃O₄) with increasing basicity during the reaction. With increasing acidic conditions, the composition of the reaction product approximates to that of maghemite (γ-Fe₂O₃); the crystal structure is disturbed. Likewise, some other reaction products will originate, their chemical composition being FeOOH.     

Bestimmung von Diffusionskoeffizienten aus der Röntgen-Kleinwinkelstreuung und Lichtstreuung von Gläsern

It is shown how to conclude from small angle X-ray scattering and light scattering of phase separated glasses what kind of phase separation process is occurring in the glass. In the cases of diffusion controlled particle growth and of spinodal decomposition, methods were presented permitting to find out from diffraction experiments the diffusion coefficients underlying these decomposition processes. The methods were demonstrated with three different glasses.     

Zur Errechnung der Intensitäten von Auger-Übergängen für die quantitative Analyse von Festkörperoberflächen mit der Augerelektronenspektroskopie (AES)

According to an empirical equation for the Auger electron intensity arising from primary electron bombardment of solid surfaces, the parameters such as ionization cross section, relative Auger transition probability, backscattering factor and mean escape depth were evaluated for the L₃M₄₅M₄₅ Auger transition of elements with atomic number Z = 22 to 33. A comparison of the calculated relative intensities with experimental values from Palmberg et al. indicates a good agreement of both curves representing the intensity in dependence of atomic number. The mean relative deviation of calculated intensities from measured ones amounts to 20%. This is nearly the same value, as it has been estimated so far for the accuracy of quantitative AES without standard. Examining the influence of individual intensity parameters we were able to show that above all the ionization cross section and in the present case also the relative Auger transition probability determine the value of intensity.