Abstract: The correlation between the microstructure and the mechanical behavior of ultrafinegrained
face centered cubic (f.c.c.) metals processed by equal-channel angular pressing (ECAP) was
studied. It was found that the maximum value of the yield strength obtained at high strains is
determined by the shear modulus and the saturation value of the dislocation density according to the
Taylor equation. It was also revealed that the value of the parameter α in this equation decreases
with decreasing stacking fault energy, indicating the effect of different geometrical arrangements of
dislocations in the grain boundaries. In addition, it was shown that for ECAP processed Cu, the
ductility decreases with increasing strain but at extremely high strains the ductility is partially
restored due to a recovery of the grain boundary structure.
Abstract: Modern trends in metal cutting, high speed/feed machining, dry cutting and hard cutting set
more demanding characteristics for cutting tool materials. The exposed parts of the cutting edges
must be protected against the severe loading conditions and wear. The most significant coatings
methods for cutting tools are PVD and CVD/MTCVD today. The choice of the right substrate or
the right protective coating in the specific machining operation can have serious impact on
machining productivity and economy. In many cases the deposition of the cutting tool with a hard
coating increases considerably its cutting performance and tool life. The coating protects the tool
against abrasion, adhesion, diffusion, formation of comb cracks and other wear phenomena.
Abstract: The Mg micropowder was mixed and ball milled with ceramic nanoparticles. The
material was compacted and then hot extruded. Samples have been deformed in tensile as well as
compression tests at temperatures between 20 and 300 °C at a constant initial strain rate. The flow
stress is significantly influenced by temperature. The yield stress and maximum stress decrease with
increasing temperature. Stress strain curves obtained at lower temperatures in tensile tests
substantially differ from ones estimated in compression. Stress relaxation tests were conducted in
order to find the internal stress as well as to identify possible thermally activated process(-es).
Abstract: The grain structure of pure aluminium processed by equal channel angular pressing
(ECAP) was examined electron backscattered diffraction (EBSD) in the as pressed state and after
heating preceding the creep deformation using various stereological methods. Area intensities of
grain and subgrain boundaries, length intensities of triple grain and subgrain junctions, structural
homogeneity and its thermal stability are strictly dependent on the number of passes.
Abstract: In the presented paper, properties of Al-Cr-Fe-Ti alloy produced by powder metallurgy
(PM) are described. Rapidly solidified powder alloy was prepared by the pressure nitrogen melt
atomization. The granulometric powder fraction of less than 45 μm was then hot-extruded.
Microstructure of the as-extruded material comprised recrystallized α-Al grains and spheroids of
intermetallic phases. Tensile strength of the investigated material was similar to that of a
conventional casting Al-Si alloy commonly used in elevated temperature applications. Excellent
thermal stability of the PM Al-Cr based material, which much exceeded the elevated temperature
casting alloy, was proved by room temperature tensile tests after long-term annealing at elevated
temperature. Reasons for the observed thermal stability of the investigated PM alloy are discussed.
Abstract: The novel bulk glasses from the chalcohalide Ge-S-AgI system have been synthesized.
From the as-prepared samples amorphous films have been deposited by vacuum thermal
evaporation. The amorphous nature of the studied bulk and layered materials has been proved by Xray
diffraction. The composition of the synthesized bulk chalcohalide glasses and corresponding
amorphous thin films has been ascertained by means of Auger electron spectroscopy. The
morphology and uniformity of the deposited layers have been investigated using scanning electron
microscopy. The basic optical properties of the studied glassy films have been defined. Variations
in the optical behaviors as a function of the composition have been derived. Experiments related to
optical recording in the investigated Ge-S-AgI layers has been implemented. The diffraction
efficiency as a function of various recording beam intensities has been obtained.
Abstract: There are two types of experimental material used – pure nickel and its nano-composite
reinforced with nano-sized SiO2. These materials were produced by TU Clausthal, Germany. The
results have shown that the creep resistance of the nickel nano-composite reinforced with nanosized
SiO2 particles is higher in comparison with non-reinforced nickel. The mechanism responsible
for creep behaviour is the dislocation creep at 293 K and at elevated temperatures the dislocation
creep is controlled by grain boundary sliding.
Abstract: We investigate critical thicknesses of InGaN epilayers grown on GaN substrates with the
growth-plane not being the c-plane. In particular, we focus on non-polar orientations with growth
planes being the m- and a-planes. We have taken into account the proper hexagonal symmetry of
wurtzite GaN. We have found that there is only a small difference in the critical thickness for the cplane
and the a-plane material; however, in the case of the m-plane material, we predict a quite
different behaviour along the (in-plane) c-axis and the perpendicular (in-plane) a-direction.
Abstract: Silver objects obtained from archaeological excavations often exhibit an extended embrittlement.
The causes of this embrittlement were studied on silver artefacts buried for more than one thousand
years in the soil using light and electron microscopy techniques and EDX microanalysis.
Our investigation revealed presence of chlorine, sulphur and oxygen along the grain boundaries
suggesting that most likely, the catastrophic failure of the grave objects made of Ag–Cu alloys is
caused by an intercrystalline corrosion attack. The role of possible grain boundary segregation
and/or precipitation of copper as a path of easy corrosion is discussed.
Abstract: Hydrogen is the promising pollutant-free fuel of the near future. For various hydrogen
applications, suitable storage systems have to be developed. One of the safe ways is the reversible
storage of hydrogen in the form of light metal (lithium or magnesium) hydrides. MgH2 magnesium
hydride shows very high storage capacity (approx. 7 wt. %), but its problem is high thermodynamic
stability. Therefore, high temperature (over 400°C) is necessary for MgH2 to decompose producing
hydrogen. The solution of this problem can be the utilization of the complex magnesium hydrides
containing nickel, copper or other transition metals.
In this work, the microstructure and hydrogen storage properties of the various magnesium alloys
(Mg-Ni, Mg-Zn, Mg-Cu and Mg-Cu-Al) are described. The aim was to find suitable hydrogen
storage system with good storage capacity and sufficient rate of formation and decomposition of
hydrides. Microstructure, chemical and phase composition of the alloys were determined by the
light and scanning electron microscopy, EDS and XRD. Hydrogen saturation was carried out by
cathodic polarization in the alkaline solution. Hydrogen content in the material was estimated by
XRD from the shift of the diffraction lines of present phases.