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The quasicrystalline phase in melt-spun Al–Mn–Be alloys was investigated. In ribbons 40–60 μm thick the phase was present in the form of small particles rather uniformly dispersed in an aluminium solid solution matrix. The quasicrystalline phase had a primitive icosahedral structure. It was confirmed that it contained a substantial amount of Be. Nonetheless, it seemed that the electron-to-atom ratio remained close to that of binary Al 80 Mn 20 quasicrystal.

In this work we characterized the structure of continuously cast small cross-section rods (O10 mm) of the Ni-based superalloy GMR 235. In the microstructure prevailed dendritic columnar γ-grains with γ′-precipitates. In the interdendritic regions MC-carbide and M3B2-boride were identified. The inverse macrosegregation was very faint, except at the secondary witness marks and natural corrugations. It was found that the alternating drawing mode had much greater influence on microstructure than other casting parameters. Special attention was given to explanation of processes leading to formation of surface marks (primary and secondary witness marks and natural corrugations). Formation of hot tears and appearance of inverse segregation is also discussed.

Ledeburitic chromium steel X155CrVMo12.1 for cold-work tools was investigated in the quenched and tempered condition. Using appropriate investigative methods the evolution of the microstructure in all conditions was characterized. The change in state of a multicomponent matrix during tempering is crucial for attaining the required properties of this steel. In the material investigated, shape, size, fraction and distribution of eutectic (primary) carbides played a secondary role. The evolution of tempered martensite and precipitation of secondary hardening carbides of M23C6-type and MC-type from the supersaturated matrix during tempering led to secondary hardening and a secondary hardness peak at about 530 °C. The results show that steel X155CrVMo12.1 also exhibits performance ability at moderately elevated temperatures.

Improved sample wettability was obtained by oxygen plasma functionalization of pyrolytic graphite. The samples were exposed to highly dissociated oxygen plasma with the density of 1 × 10 16 m −3 , the electron temperature of about 5.5 eV and the density of neutral oxygen atoms of 8 × 10 21 m −3 for 20 s. The surface wettability was measured by a contact angle of water drop. The contact angle dropped from original 112° down to about 1°. The functional groups were detected by XPS analyses. The survey spectrum showed a substantial increase of oxygen concentration on the surface, while high-resolution analyses showed additional oxygen was bonded onto the graphite surface in the form of C–O polar functional group responsible for the increase of the surface energy.

Magnetic micro-actuators and systems (MAGMAS) require tiny permanent magnets with dimensions of hundreds of micrometers. Such magnets need to have the highest possible energy density, which means Nd–Fe–B magnets are the most appropriate type. Most bottom-up fabrication techniques are either too slow or too expensive; top-down techniques involving machining tend to result in surface damage and a loss of magnetic properties. In this study, we have looked at very neodymium-rich Nd–Fe–B powders that allow us to sinter 100-μm-thick samples to full density at temperatures as low as 800 °C. These very thin magnets have coercivities of up to 1000 kA m −1 and are suitable for MAGMAS-type applications.

In this work a Ni-based superalloy GMR 235 was investigated. We determined convenient metallographic methods for preparation of bulk metallographic specimens, extraction carbon replicas, transparent metallic foils and minor phase extraction. In addition, the alloy microstructure was characterised using different metallographic techniques.

In a Late Bronze Age hoard at Kanalski Vrh in Slovenia, bronze pendants were found among numerous other artifacts. Among them a group of nine pendants of very similar compositions contained higher amounts of antimony, arsenic, nickel, cobalt, and iron, which suggested that speiss was added to bronze. Furthermore, most pendants had a silvery grey surface that differed from the common color of tin bronze, with about 13% Sn. One of the pendants was analysed by light optical and electron microscopy, Auger electron spectroscopy (AES), X-ray diffraction (XRD), and differential thermal analysis (DTA). Analyses revealed that the surface of the pendant was corroded, the copper alpha phase was eaten away, and the remaining eutectoid phase exhibited that silvery grey color. Comparison of chemical composition of the pendant and of compositions of speiss ingots found in the same hoard indicated that speisses could be used as alloying additions in making melts for casting pendants.

Alloys of the quasibinary section Cu –NiBe were experimentally investigated with differential thermal analysis, optical microscopy, electron microanalysis, transmission electron microscopy and X-ray diffraction. The construction of the quasibinary Cu–NiBe phase diagram was made based on the experimental results. The constitution of alloys of the whole section was studied along with the investigation of the microstructure and crystallographic relationship of the NiBe phase in aged alloys from the Cu-rich corner of the Cu–NiBe system.

The Ni-based superalloy GMR 235 was investigated in different as-cast conditions. It consisted of the γ matrix with γ ′ precipitates, and of three minor constituents: M 3 B 2 , MC and Ti(C,N). The cooling rate influenced the size and morphology of microstructural constituents, and the composition and lattice constants of M 3 B 2 and MC.

In arc melted and aluminothermically prepared alloys with composition in the triangle Al–AlB2–TiB2 four solid phases are observed: α-Al, ρ-AlB12, AlB2, and TiB2. The univariant reaction between L, ρ-AlB12, and TiB2 is the eutectic one L⇌ α-AlB12 + TiB2. During the reaction TiB2 platelets are sequentially formed on facets of α-AlB12, but their formation may be completely suppressed by the presence of primary TiB2. Decomposition of α-AlB12 does not occur on cooling, but only during isothermal annealing under 900°C probably according to the transition reaction L + α-AlB12 → TiB2 + AlB2. Dissolution of α-AlB12 and growth of AlB2 take place in afaceted manner owing to their high entropies of solution. The low temperature AlB2 phase is not formed at all on cooling of concentrated alloys with an overall composition lying on the AlB2-TiB2 tieline, whereas in less concentrated alloys it is usually formed on the primary TiB2 particles in the regions distant from α-AlB12

Diborides present in Al-Ti-B alloys with a weight ratio TilB < 2.2 are investigated in the arc melted and annealed conditions as well as in the controlled heated and cooled specimens by means of light and scanning electron microscopy, energy dispersive spectrometry and X-ray diffraction. In Al- Ti-B alloys with composition close to the AlB2-TiB2 tieline; apparently pure spheroidal and platelike TiB2 particles are present. In the as cast condition of all other investigated alloys the formation of AlB2 on primary TiB2 particles is observed regardless of the applied cooling rate. In the investigated alloys apparently pure TiB2 and AlB2 coexist even after 1000 h exposure at 800° C, and the formation of mixed diboride (Al, Ti) B2 was never observed. The results of this work are discussed together with the results of previous work in this area and it seems very likely that the mixed diboride (Al, Ti)B2 is not a thermodynamically stable phase in the aluminium rich corner of the Al-Ti-B system, but onlyap...