[en] After a brief general introduction to ionising radiation and its effect on human tissues a detailed treatment of the physics and biology determining the acceptable dose levels is provided. Finally radiation protection regulations and radiation environments are discussed. (J.H.)

[en] Problems related to ionizing radiations are taught extensively in the course of physics. Some risks of biological effects for both teachers and students have to be considered. Types of ionizing radiations, concepts and units are described, permissible dose rates and safety regulations for open and sealed radiation sources, X-ray equipment etc. are given in form of recommendation for school labs. (EG)

[en] Single crystals of Cobalt with the <0001> axis normal to the surface were used. When heated above the transition temperature, the <0001> axis transforms to a <111> axis in the f.c.c. structure. Both the total sputtering yield and the angular distribution in yield were investigated. The experimental results show a pronounced reduction in sputtering yield of the f.c.c. structure compared to the h.c.p. structure. (Auth.)

[en] Radiation damage microstructure and associated disorder have been investigated in antimony implanted nickel crystals using combined RBS and TEM analyses. In crystals implanted at and below room temperature with 80 keV Sb⁺ ions to a fluence of 5x10²⁰ m^-2, the retained antimony concentration in the implantation zone is approaching 15 at.%, with nearly all the antimony located substitutionally. The associated disorder as seen in the RBS analysis is insignificant. Annealing up to 600⁰C has little influence on the antimony distribution, whilst the dechanneling level is reduced. TEM and diffraction analysis of room temperature implanted samples show that the radiation damage consists of dense distributions of dislocation clusters and tangles, superimposed on a rather homogeneous background of new phase particles, identified as hcp nickel. The particles have a size 0.1-0.2 μm. The high substitutional antimony concentration at and below room temperature, which exceeds the solubility limit, indicates that its formation is thermally diffusionless and rather an effect of radiation enhanced solubility. The diffusionless nature of the microstructure is also indicated from the presence of martensitic hcp nickel, believed to form due to relief of radiation induced internal stress. (Auth.)

[en] Single crystals of cobalt have been bombarded with 80 keV A⁺ ions in the <0001> direction of the h.c.p. structure and in the <111> direction of the f.c.c. structure. The sputtering yields, measured by the weight loss method, depend on the crystal structure, and damage, introduced by the ion bombardment, is shown to play a significant role in the explanation of the measured sputtering yields. (Auth.)

No abstract available

[en] Non-uniform distributions of solute content in the supersaturated α Al matrix and inhomogeneous precipitation of metastable/stable phases have been studied in rapidly solidified Al-Cu and Al-Zn ribbons. Double peaked X-ray diffraction lines from the α Al matrix were observed in three as-quenched Al-Cu alloys and one annealed Al-Zn alloy. For as-quenched Al-Cu ribbons, variations in composition, microstructure and precipitate density across the ribbons results from local differences in coolingrates. These differences originate from recalescence during the solidification. The double peaked diffraction lines for these alloys corresponds to two compositions of the α Al phase with less copper solute in the topside than in the wheelside of the ribbons. Subsequently, annealing of the samples leads to inhomogeneous precipitation of the metastable Θ' phase across the whole thickness of the ribbons. Such inhomogeneities do not appear in as-quenched Al-Zn alloys which are quenched into a single α Al phase. Splitting of the diffraction lines in the annealed ribbons arises from differences in the composition of two different α Al matrix phases. The α Al phase between the R phase lamellae has low zinc content, while the α Al phase where high densities of G.P. zones are retained has higher zinc concentration. (orig.)

No abstract available

[en] Thermodynamic properties of the melts of several Al-Y and Al-Fe-Y alloys are studied by means of calibrated differential thermal analysis. The results can be used to optimize process parameters of rapid solidification which are important for glass formation in the Al-based alloys. Close examinations of the melt-spun alloys show that the process parameters, particularly the temperature of the melts, will influence not only the amorphicity and the chemical short range order but also the crystallization process of the glasses. A key point of glass formation in the Al-based alloys in found to be related to the content in the melts of certain amount of the intermetallic compounds which are gradually dissolved into the premelted α Al matrix. (orig.)

[en] Crystallization reactions, crystal morphologies and evolutions have been studied in meltspun binary Al-Y and ternary Al-Fe-Y metallic glasses using X-ray diffraction, differential scanning calorimetry, electron microscopy and Moessbauer spectroscopy. The binary samples crystallize in an one-stage or two-stage primary reaction of α Al phase, followed by polymorphous reactions of different metastable compounds. The ternary glasses devitrify in either polymorphous or eutectic reactions. The ternary crystalline compounds are characteristically a metastable Al₉ (Fe,Y)₂ phase with strongly textured columnar morphology, and a tetragonal Al₇₀Fe₁₆Y₁₄ phase. The structure of the early stage crystallization products depends on the nature of the short range chemical order structures existing at different temperatures in the melts, which are partly retained in the glass phases. (orig.)