Particles of the Fe-Al type (less than 50 µm in diameter) were sprayed onto the 045 steel substrate by means of the detonation method. The TEM, SAED and EDX analyses revealed that the Fe-Al particles have been partially melted in the experiment of coating formation. Particle undergone melting even within about 80% of its volume. Therefore, solidification of the melted part of particles was expected. Solidification differed significantly due to a large range of chemical composition of applied particles (from 15 at.% Al up to 63 at.% Al). A single particle containing 63 at.% Al was subjected to the detailed analysis, only. The TEM / SAED techniques revealed in the solidified part of particle three sub-layers: an amorphous phase, A ε , periodically situated FeAl + Fe2Al5 phases, and a non-equilibrium phase, Nε . A hypothesis dealing with the inter-metallic phases formation in such a single particle of the nominal composition 0 N = 0.63 is presented. At first, the solid / liquid system is treated as an interconnection: substrate liquid nonmelted particle part / / . Therefore, it is suggested that the solidification occurs simultaneously in two directions: towards a substrate and towards a non-melted part of particle. The solidification mechanism is referred to the Fe-Al meta-stable phase diagram. It is shown that the melted part of particle solidifies rapidly according to the phase diagram of meta-stable equilibrium and at a significant deviation from the thermodynamic equilibrium.

High pressure die casting (HDPC) allows to produce aluminum parts for car industry of complicated shapes in long series. Dies used in this process must be robust enough to withstand long term injection cycling with liquid aluminum alloys, as otherwise their defects are imprinted on the product making them unacceptable. It is expected that nitriding followed by coating deposition (duplex treatment) should protect them in best way and increase intervals between the cleaning/repairing operations. The present experiment covered investigations of the microstructure of the as nitride and deposited with CrAlN coating as well as its shape after foundry tests. The observations were performed with the scanning and transmission electron microscopy (SEM/TEM) method. They showed that the bottom part of this bi-layer is formed by roughly equi-axed Cr2N crystallites, while the upper one with the fine columnar (CrAl)N crystallites. This bi-layers were matched with a set of 7x nano-layers of CrN/(CrAl)N, while at the coating bottom a CrN buffer layer was placed. The foundry run for up to 19 500 cycles denuded most of coated area exposed to fast liquid flow (40 m/s) but left most of bottom part of the coating in the areas exposed to slower flow (7 m/s). The acquired data indicated that the main weakness of this coating was in its porosity present both at the columnar grain boundaries (upper layer) as well as at the bottom of droplets imbedded in it (both layers). They nucleate cracks propagating perpendicularly and the latter at an angle or even parallel to the substrate. The most crack resistant part of the coating turned-out the bottom layer built of roughly equiaxed fine Cr2N crystallites. Even application of this relatively simple duplex protection in the form of CrAlN coating deposited on the nitride substrate helped to extend the die run in the foundry by more than three times.

Detailed studies on the effects of pulsed laser interference heating on surface characteristics and subsurface microstructure of amorphous Fe80Si11B9 alloy are reported. Laser interference heating, with relatively low pulsed laser energy (90 and 120 mJ), but with a variable number (from 50-500) of consecutive laser pulses permitted to get energy accumulation in heated areas. Such treatment allowed to form two- Dimensional micro-islands of laser-affected material periodically distributed in amorphous matrix. The crystallization process of amorphous FeSiB ribbons was studied by means of scanning and transmission electron microscopy. Detailed microstructural examination showed that the use of laser beam, resulted in development of nanostructure in the heated areas of the amorphous ribbon. The generation of nanocrystalline seed islands created by pulsed laser interference was observed. This key result may evidently give new knowledge concerning the differences in microstructure formed during the conventional and lased induced crystallization the amorphous alloys. Further experiments are needed to clarify the effect of pulsed laser interference crystallization on magnetic properties of these alloys.

Mechanical components and tools in modern industry are facing increasing performance requirements leading to the growing need for advanced materials and thus, for modern frictional systems. In the last decades, the Pulsed Laser Deposition (PLD) has emerged as an unique tool to grow high quality mono- as well as multilayers surfaces in metallic/ceramic systems. Building up a knowledge base of tribological properties of industrially-scaled, room temperature deposited PLD hard coatings are the most important step for the application of these coatings in engineering design. Although single-layer coatings find a range of applications, there are an increasing number of applications where the properties of a single material are not sufficient. One way to surmount this problem is to use a multilayer coating. Application of metallic interlayers improves adhesion of nitride hard layer in multilayer systems, which has been used in PVD processes for many years, however, the PLD technique gives new possibilities to produce system comprising many bilayers at room temperature. Tribological coatings consisted of 2, 4 and 16 bilayers of Cr/CrN and Ti/TiN type were fabricated with the Pulsed Laser Deposition (PLD) technique in the presented work. It is found in transmission electron examinations on thin foils prepared from cross-section that both nitride-based multilayer structures studied are characterized by small columnar crystallite sizes and high defect density, what might rise their hardness but compromise coating adhesion. The intermediate metallic layers contained larger sized and less defective columnar structure compared to the nitride layers, which should improve the coatings toughness. Switching from single layer to multi-layer metal/nitride composition improved resistance to delamination.

Paper describes the results of Fe80Si11B9 amorphous ribbon investigation after pulsed laser interference heating and conventional annealing. As a result of interference heating periodically placed laser heated microareas were obtained. Structure characterisation by scanning and transmission electron microscopy showed in case of laser heated samples presence of crystalline nanostructure in amorphous matrix. Microscopy observations showed significant difference in material structure after laser heating – nanograin structure, and material after annealing – dendritic structure. Magnetic force microscopy investigation showed expanded magnetic structure in laser heated microareas, while amorphous matrix did not give magnetic signal. Change of magnetic properties was examined by magnetic hysteresis loop measurement, which showed that the laser heating did not have a significant influence on soft magnetic properties.

The lack of room-temperature ductility of high-strength TiAl-based alloys called for complicated high temperature processing limiting their application areas. Introduction of additive manufacturing (AM) methods allowed to circumvent this disadvantage, but entailed microstructure refinement affecting, among the others, their oxidation resistance. The dry-air high temperature oxidation processing of TiAl-based alloys is relatively well covered for coarse grained materials, but to what extent the TiAl alloys are affected by the changes caused by the AM remains to be found out. Additionally, the role of nitrogen during these processes was to large extent omitted in previous works. Within the present experiment, the mould cast (MC) and the electron beam melted (EBM) Ti-48Al-2Nb-0.7Cr-0.3Si (at. %) RNT650 alloys were dry-air oxidized at 650°C for 1000 h. The TEM/EDS investigations allowed to confirm that the scale formed during such treatment consists of the layers occupied predominantly by TiO2+Al2O3/TiO2/Al2O3 sequence. Additionally, it was shown that N diffuses to the sub-scale and reacts with the substrate forming two distinct discontinuous sub-layers of α2-Ti3Al(N) and TiN. The scale over EBM was noticeably less porous and nitrogen penetration of the substrate was more extensive, while the MC showed higher susceptibility to local sub-scale oxidation.