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Two kinds of phase stabilization mechanism are discussed and compared: the first is characteristic of the formation of bulk amorphous alloys, in which the high supercooling ability of multicomponent liquids is responsible for the glassy phase stabilization. Here the hindered nucleation of crystalline phases is the center phenomenon. The origin of this hindering is the slowing atomic mobility in the supercooling melt. In contrast the melt supercooling is negligible during the high entropy alloy formation. It is believed that stability of the crystalline single fcc phase is the consequence of the characteristic of high configurational entropy at high temperatures. However, the significance of this entropy-dominated stabilization is overestimated in several references. It has been concluded that transition metal contraction (arising from the d electron participation in the overall bonding state) does also contribute to the high temperature stability of fcc single phase in the high entropy alloys.

Két ötvözetcsalád, a tömbi formában előállított amorf (BMG) és a nagy entrópiájú (HEA) ötvözetek képződési mechanizmusát és stabilitását hasonlítjuk össze jelen közleményben. Az összehasonlítás fő elve az olvadékaik túlhűlési képessége a megszilárdulás folyamatában. A BMG-ötvözetek olvadékai a különböző típusú kémiai kötések miatt nagy túlhűlési hajlamot, s ebből eredően nagy üvegképző hajlamot is mutatnak. Ennek jellemző mechanizmusa a klaszterképződés, amellyel az atommozgékonyság s így a kristálycsíra-képződés is visszaszorul. A HEA-ötvözetek olvadékai nem mutatnak ilyen hajlamot. Nagy hőmérsékleten, közvetlenül az olvadáspont környékén, az olvadékfázissal azonos összetételű, rendezetlen szilárd oldat formájában kristályosodnak. A kétféle olvadéktípusban az eltérő atomi mobilitás tükröződik az olvadékok viszkozitásának eltérő hőmérséklet-függésében is. A HEA-ötvözeteknek a konfigurációs entrópia által dominált fázisstabilitásához elektronszerkezeti tényezők is hozzájárulnak: itt szerepet kap a d-elektronok részvétele az atomok közötti kötésekben.

In the present work the comparison of the effect of traditional, pulse and stress annealing is made by monitoring the important mechanical and magnetic properties of FINEMET type amorphous precursor alloy. The magnetic properties were determined from the shape of magnetization curve (coercive force, anisotropy) during various heat treatments and the mechanical properties were measured using brittleness test. The traditional heat treatments were performed in resistance furnace and the magnetic measurements were performed in astatic magnetometer. The pulse and stress annealing (as well as their combinations) were carried out inside in the magnetometer. The temperature of pulse heat treatments is regulated with the length of current pulse flowing through the sample. After each pulses the magnetization curves were measured in-situ, in the magnetometer.

In my study I present the urban environment as a space for walking a dog from the perspective of the dog owner. I analyze the activity of walking a dog as the most characteristic manifestation of the contact between public space and the dog owner, and using the method of mental mapping. I explore how dog owners perceive public space when walking their dogs. The initial hypothesis of my research was that dog owners use public spaces differently from others when they try to construct and satisfy the (assumed) needs of another creature from their viewpoint. During walks, owners use public spaces in a way that, according to their conception, suits their dogs the most. We could also say that they aim to use space from the dog’s perspective, as they can conceive of this. Urban dog keepers vary in terms of motivation, dog-keeping practices and lifestyle, thus we cannot speak about them in general. However, through examining different individuals and groups it is possible to identify some features of the “dog lifestyle.” This is important as there is a growing need to identify and understand this specific lifestyle model. In today’s urbanism, the role of multifunctional spaces is increasingly significant as such spaces are being created not to the detriment of the different sub-social groups, but by taking specific needs into consideration.

A short survey is reported on the advantageous and disadvantageous properties of soft magnetic glassy tapes to build stator and rotor elements for the increase of motor efficiency. The relative high saturation magnetization and the relative permeability of these alloy groups seem to be promising in this application field. On the other hand, the sample thickness (30 µm) displays limitations in terms of a filling factor. High hardness of tapes hinders the effectivity of mechanical shaping. Laser cutting can be successful as shaping method, presuming that the extension (thickness) of heat affected zone (HAZ) can be successfully reduced below 50µm, avoiding the brittleness evolution.

In my study I present the urban environment as a space for walking a dog from the perspective of the dog owner. I analyze the activity of walking a dog as the most characteristic manifestation of the contact between public space and the dog owner, and using the method of mental mapping I explore how dog owners perceive public space when walking their dogs. The initial hypothesis of my research was that dog owners use public spaces differently from others when they try to construct and satisfy the (assumed) needs of another creature from their viewpoint. During walks, owners use public spaces in a way that, according to their conception, suits their dogs the most. We could also say that they aim to use space from the dog’s perspective, as they can conceive of this. Urban dog keepers vary in terms of motivation, dog-keeping practices and lifestyle, thus we cannot speak about them in general. However, through examining different individuals and groups it is possible to identify some features of the “dog lifestyle.” This is important as there is a growing need to identify and understand this specific lifestyle model. In today’s urbanism, the role of multifunctional spaces is increasingly significant as such spaces are being created not to the detriment of the different sub-social groups, but by taking specific needs into consideration.

The focus of this paper is the deeper understanding of the effect of the change in the electronic structure on the wetting angle and transport properties. For this purpose, using the alloys from the earlier study, the thermopower has been measured and the Seebeck coefficient has also been determined in room temperature (solidified state). During the experiments in both case the modification of the electronic structure were performed by alloying on a way, that the investigated systems are terminal (α) solutions in solid state. The concentration dependence of property changes are interpreted on the bases of free electron model elaborated earlier for this alloy types. This prediction fits well also to the concentration dependence of heat of formation in these alloys. Similar concentration dependence has been also found between the Seebeck coefficient, the resistivity and the heat of mixing in α-phase Fe-Ni alloys. The shift of thermopower were also monitored in order to detect the crystallization (first oreder transformation) starting form amorphous Fe-B alloys.

A survey of the cluster formation tendency and mechanism in transition metal-based glassy alloys is made with an emphasis on their manifestation in various physical properties. The cluster formation is partially inherited from the supercooling of the melt. However, it also develops due to the interaction between dissolved hydrogen and the frozen glassy structure. The glassy state as “cluster assembly” is regarded as a structural background for the interpretation of several anomalous concentration dependences of thermal and magnetic properties in these glasses. We will focus on the manifestation of alloying effects, the relation between irreversible and reversible structural relaxations both in the high, and low temperature range (observed near to the glass transition or after low temperature storage). The development of the cluster assembly is the consequence of the co-existence of various bonding types between the alloy components. These are brought together in the melt, ensuring sufficient glass-forming ability. The nucleation mechanism of the amorphous-nanocrystalline transformation is also explained as a cluster phenomenon, which significantly contributes to the evolution of magnetic ultra-softness in FINEMET-type alloys. Finally, the role of the quenched-in cluster structure in the mechanism of reversible and irreversible H-absorption is discussed. Irreversible H-induced structural rearrangements can appear as microphase separation in multicomponent systems, governed by the affinity difference between the metallic components and the absorbed hydrogen. This kind of H-induced reordering is responsible for the “volume activation” of amorphous H-storage alloys and it also causes the gradual breakdown of storage capacity during cyclic absorption–desorption steps. This article mainly focuses on the cluster phenomena in Fe-based glasses because of its unique combination of high mechanical strength, strong corrosion resistance, good thermal stability and excellent magnetic properties.

The temperature dependence of wettability (wetting angle, Θ(T )) for Ag-based melts on graphite and Al2O3 substrates is compared. Typical alloying e ects are found, as the Ag host metal is gradually replaced by various metallic elements. The essence of alloying lies in the change of the electron/atom (e/a) ratio. This ratio is also manifested in the shift of wetting angles on the same substrate. The e ect is also supported by the calculations based on the rigid band model, and is also in qualitative agreement with the Hume-Rothery rules. Nevertheless, the e ects are partially smeared by other (metallurgical) factors, like the interaction between the oxygen-alloying elements and by the graphite substrate oxygen interaction. In contrast, such e ects are not pronounced in the case of Al2O3 substrates. As a consequence, Θ(T ) exhibits an opposite trend in the case of two substrates. Crossovers of the Θ(T ) curves were often found. The positions of crossovers depend on the chemical character and concentration of solute atoms. Segregation and epitaxial texture formation after solidi cation were also observed in certain alloy drops, especially in high concentration range. This phenomenon is not yet explained in every detail. DOI: 10.12693/APhysPolA.124.78

The transformation following the regime change radically reshaped the structure of production in the South Bihar region of Hungary. After the liquidation of the cooperative farms created during the socialist era, a variety of farming alternatives was present simultaneously, but collective production forms of a new kind were formed only sporadically. As a result a substantial part of the local population became unemployed, suffering a loss of position and status. At the same time, entrepreneurs who were quick to recognise the direction of change and were able to adapt flexibly to the constantly changing conditions gradually strengthened their financial position and increasingly became key actors in local society. This restructuring of society following the economic transformation continues to be a considerable conflict-generating factor among the local population.

The wettability of graphite by the silver–tin (Ag–Sn) liquid alloy was measured using the sessile drop method at a temperature interval of 1273–1473 K. The system is found poorly wetting with the contact angle at an interval of 125…142°. The contact angle passed through an elongated maximum as function of composition and increased with temperature. It was shown that no dissolution or chemical reaction takes place in the system up to 1473 K. The Butler equation was extended to calculate the concentration dependence of surface tension, solid/liquid interfacial energy and that of the contact angle theoretically. The theoretical results reasonably reproduce the measured values.

The wettability of graphite by the Ag-M based (M: Cd, In Sn, Sb) liquid alloys was measured using the sessile drop method at a temperature interval of 1273 1473 K. Except the Ag-Cd alloys, the investigated systems exhibit worse wettability than that of Ag (host metal) melt, within the investigated temperature range. The compositional and concentration dependence of contact angle (Θ) exhibits similar trends, than the residual resistivity change measured in the same alloys in solid state. Nevertheless, the measured segregation effects during the solidification are not significant.

The amorphous alloys, especially the bulk metallic glasses (BMGs), possess special properties, making them very attractive for applications as structural and functional materials. The most important criterion for amorphization is that during cooling from the liquid state crystal nucleation and growth is avoided. The casting technologies currently available do not allow preparation of amorphous parts with complicated geometries. A DC electrical current applied between the molten metal and the mold during the ejection may inhibit heterogeneous nucleation by modifying the surface tension of the liquid alloy. More, by reducing the surface tension, the molten alloy flows better, filling even complicated molds. Using this new technique, the casting processes may become reproducible and can be relatively easily scaled up to the industrial requirements for mass production.

The wetting angles (Θ) of Ag-M based melts (M: Cd, Sn, Sb) on graphite and Al2O3 substrates are compared. Despite of the inert chemical character and the similar surface roughness of substrate materials, the wetting angle is smaller on the Al2O3. The compositional and concentration dependence of Θ exhibits similar trends, than that, observed in the bulk transport properties such as the specific electrical resistance or the thermopower obtained on the same alloys in solid state. No segregation effects can be detected on the solidified metal drops.

For the study of stress state in engineering alloys, the thermopower (S) measurement could be acceptable method after a suitable calibration (fitting the S value to the change of well known other physical parameters like the magnetic coercive force, hardness or strength increase during various thermomechanical treatments). For this purpose a simple equipment is constructed and built by which the S shift can be measured versus the increasing mechanical tensile load. The first results will be published in this paper, obtained on various metallic glass ribbons.

The influence of cryo-treatment is investigated according to some magnetic and thermal properties of Fe40Ni40Si6B14 glassy alloy. Saturation magnetization (MS), amorphous Curie temperature (TC am) heat capacity (Cp) and the width of crystallization exotherm peak were measured before and after the cryo-treatment. The treatment causes a very stable structural imprint in the investigated properties. Not all property changes are completely irreversible, however. The TC am exhibits a very slow, viscous reconstruction during subsequent isothermal or cyclic heat treatments. The heat capacity of cryo-treated samples increases compared to the nontreated ones. Due to the low temperature treatment the kinetic of crystallization changes also, which is manifested in the shift of half width of crystallization peak. The magnitude of the LN treatment induced effects depends on the whole thermal history of the sample.

The wetting angle (Θ) of molten Ag (Zn, Cu, Ga) drops on graphite substrate is investigated. A texture formation was found in the substrate/drop interphase region after solidification. The enrichment (segregation) of Ag atoms in the interface layer was observed in the Ag-Cu alloy, and unexpected mixing between graphite substrate and the Ag-Ga melt was also detected in the solidified structure.

The wetting phenomenon between solids and liquids has an outstanding role in several technological processes [1, 2]. The knowledge of physical and chemical factors acting on the surface tension is needed to ensure the successful processing in casting, brazing and sintering. The surface oxide layer influences the wetting conditions and makes difficult the exact measurement of contact angle [3]. In this paper the effect of oxide layer disruption and recovery was observed using a high speed camera.

A non-monotonic compositional dependence of the amorphous Curie temperature (T am c ) and of the thermopower (S) was found in Fe80−xCrxB15 glassy samples. The significant change in the slope of concentration dependence of both properties lead to the conjecture of a hidden structural change in amorphous state. Similar anomalies were also observed earlier in the concentration dependence of microhardness in the same glasses, which clearly contradicts to the traditional homogeneous single phase concept of glassy state. The results are interpreted on the basis of the existence of quenched-in phase reminiscences (clusters) in these alloys inherited from the liquid state.

In Fe based glasses not solely the stress-sensitive magnetic properties, but also the amorphous Curie temperature (T am C ) can be altered by hydrogen absorption or due to the low temperature “heat treatments” in liquid N2 (−196◦C). The sign and magnitude of this T am C shift is strongly compositional dependent, but it is also influenced by the thermal history of glasses (heat treatments). In this paper new experimental results are presented, which were obtained on FeCrB alloys, supporting the previous observations. An attempt of interpretation of the results is also made, which is based on the existence of the quenched-in phase reminiscences, being inherited from the liquid structure.

The formation of a single-phase nanocrystalline Hf61Fe39 alloy with the fcc-Hf2Fe structure was achieved in a single step by melt-quenching, similarly to the previously reported nanocrystalline HfNi5 phase in a melt-quenched Hf11Ni89 alloy. Structural studies by X-ray diffraction and transmission electron microscopy have been performed for the nanocrystalline Hf61Fe39 alloy in both the as-quenched state and after various heat treatments. It was found that the as-quenched state exhibits an average grain size of about 50 nm and a lattice parameter remarkably lower than the value known for the stoichiometric fcc-Hf2Fe phase. Differential scanning calorimetry has been used to reveal phase transformations and to establish the heat evolution and activation energy of transformation. The nanocrystalline Hf61Fe39 alloy shows high thermal stability with an activation energy of 1.29 eV corresponding to a grain growth above 800 K.

A new alloy exhibiting high glass-forming ability was developed with the composition Fe70.7C6.7P10.4B5Si1.1Mn0.1Cr2Mo2Ga2. This alloy exhibited excellent castability enabling net-shape-casting. The samples were prepared by copper-mould casting in conical rod form which has a small diameter of 3 mm, a large diameter of 4 mm, and a length of 54 mm, as well as in ring form with an outer diameter of 26 mm, an inner diameter of 18 mm and a thickness of 1 mm. The BS and HC values in DC conditions determined for the ring sample in the as-cast state are 0.45 T and 1.7 A/m, respectively, and for the ribbon in the as-cast state 0.5 T and 3.8 A/m, respectively. On the basis of the measured properties, large industrial use of this new alloy can be predicted.

An additional cryogenic effect will be reported obtained on hypo-eutectic FeB alloys. After resting the samples at low temperature (such as liquid N2, 77 K), the decrease in H solubility was detected by measuring the time dependence of pressure change in a hermetically closed chamber. The cryogenic treatment also caused a systematic lowering of the Curie temperature of the amorphous phase (TCam), similarly to that, observed in other types of Fe-based glasses.

The irreversible and reversible Curie-point relaxation was studied in FeNi-based liquid-quenched glasses. An unusual diffusionless transformation was detected during low temperature ageing in liquid N2 causing a hidden structural imprint in the glassy samples. The coercive force and permeability are also modified by this transformation.

Magnetic and structural properties of amorphous Co80-xCrxSi6B14, x=0, 2, 4, 6 and 8 at. , alloys were investigated. Temperature dependences of saturation magnetizations and relative initial susceptibilities were compared with the temperature dependences of heat flow obtained by DSC technique. Two crystallization temperatures were obtained in the temperature range 300-870 K. First crystallization leads to the formation of magnetically harder ferromagnetic material. Second crystallization additionally increases magnetization of the samples with 0 and 2 at. Cr and decreases it for higher Cr content. Concentration dependences of saturation magnetization, Curie as well as crystallization temperatures are reported. Increase of Cr contents decreases coercive fields of alloys. The influence of the under-critical annealing on the coercivity is discussed.

The influence of chromium admixture on magnetic properties of amorphous FeB ribbons in hydrogenation and dehydrogenation processes is studied. The measurements of demagnetization factor, the anisotropy constant induced by internal stress, and coercivity indicate that the presence of Cr atoms increases the internal stress in the structure and probably influences the size of stress centers created by hydrogenation. The concentration of sites which can be accessed and occupied by hydrogen, hydrogen diffusion rate and hydrogen atom distribution in a sample cross-section depend on Cr content in a complex way.

The time dependence of dehydrogenation is investigated by the measurement of stress sensitive magnetic properties in FINEMET type alloys after various degree of amorphous-nanocrystalline transformation. It was found that defect structure is dominantly responsible for the sensitivity to hydrogen absorption and desorption in this alloy, and the nanograin formation has only a minor significance in this respect.

The amorphous-crystalline transformations were studied in the case of glassy Fe70.7C6.7P10.4B5Si1.1Mn0.1Cr2Mo2Ga2 alloy prepared in the form of bulk ring, and thin ribbon (thicknesses are 1 mm, and 24 μm respectively). Although both samples are “XRD amorphous” there are clear differences in the devitrification behaviour as it can be revealed by DSC and thermo-magnetic measurements. These differences are discussed in terms of inherent structural heterogeneity of the bulk sample.

Continuing the earlier experiments, a series of new effects will be presented in this paper which demonstrate, that the amorphous Curie temperature (TCam) can be altered by resting the samples at low temperature such as (liquid N2, 77 K). The sign and magnitude of this shift depends on the alloy composition, but can also be influenced by the rate of liquid quench applied during the ribbon formation. TCam is lowered during liquid N2 treatments for the binary Fe85B15 glass. The effect is the same when a small amount of Si is added to the Fe85B15. Exceeding the critical concentration limit of the Si, the sign of TCam changes.

Two reversible relaxation processes of similar activation energies can be separated in Cr-doped FeNiSiB metallic glasses by combined Curie-point and enthalpy-relaxation measurements. While one of the processes has a positive contribution to the activation-energy spectrum of the Curie-point, the other gives a negative contribution to it. The positive effect is associated with the ordering of Fe and Ni atoms in the FeNiSiB matrix while the negative effect is attributed to the Cr atoms.

The frequency dependence of permeability change due to 1% mechanical deformation is investigated in FINEMET-type soft magnetic cores after various degree of amorphous-nanocrystalline transformation. It was found that stress sensitivity is especially high at the early stage of nanograin formation, and gradually decreases as the Si-content of the nanograin assembly increases. The permeability changes are correlated with TEM and X-ray diffraction results.

The aim of this work was to find a relation between thermal and thermomagnetic effects associated with structural phase transitions of amorphous Fe-based alloys. We have investigated Fe85−xCrxB15 amorphous alloys (0⩽x⩽11.5) by means of differential scanning calorimetry and thermomagnetometry. The measurements were carried out in the range from room temperature up to the Curie point of iron. The phases formed upon heating at high temperatures were identified by X-ray diffraction. A diagram containing the phase transformations obtained from the experimental data is presented and discussed.

The possible origin of short range atomic displacements coupled with the irreversible amorphous Curie temperature relaxation (∆T am C ) in Fe-based glasses is discussed and analyzed on the basis of quenched-in phase reminiscences. The displacements are dominantly symmetry changes, which are governed by the relative stability of fcc and bcc quenched-in phase reminiscences at a given temperature range. Those of elements which cause positive ∆T am C in as quenched state, also cause positive irreversible ∆T am C during structural relaxation. The influence of Cr addition is just the opposite in this respect.

The thermal, thermomagnetic properties as well as the frequency dependence of permeability are compared for bulk amorphous alloys with the composition of Fe 70.7 C 6.7 P 10.4 B 5 Si 1.1 Mn 0.1 Cr 2 Mo 2 Ga 2 and Fe 65.5 Cr 4 Mo 4 Ga 4 P 12 C 5 B 5.5 . The details of devitrification differ mainly in the thermomagnetic measurements. The shape of thermomagnetic curve hints to the formation of hard phase in the case of sample with higher Fe-content. Frequency dependence of the permeability shows unfavorable manner when the temperature of heat treatment approaches the glass transition regime. Contrary, heat treatment at 400 ∘ C has a beneficial effect on the high-frequency permeability.

H-induced increase in the amorphous Curie temperature ( T C am ) of FeCrB glassy alloys was detected where the relaxation effect associated with the measuring process is negligible. The increase is reversible and tends to disappear as the spontaneous desorption process proceeds at room temperature. The negligible effect arising from irreversible relaxation was separated successfully by applying appropriate control measurements on as quenched samples.

We have investigated the influence of chromium on the magnetic after-effect (MAE) of amorphous Fe 85 − x Cr x B 15 ( x = 0, 2, 3, 5 and 7) alloys. Isochronal curves were obtained for times t = 5, 10, 30, 60, 120 and 180 s in the temperature interval from 77 K up to T c . A computer analysis was performed to evaluate the spectra of activation energies from these measurements. The spectra of activation energies have a characteristic shape with a peak at the value of 1.2–1.4 eV. The pre-exponential factors are found to lie between 4 × 10 −13 and 1.1 × 10 −17 s. This indicates that the MAE can be assigned to short range atomic reorientation near free volumes. It follows from the isochronal MAE measurements that the addition of Cr atoms also causes a decrease in MAE amplitude as well as a decrease in Curie temperature. The higher the Cr-contents, the lower the MAE and the preexponential factor τ 0 .

The thermopower (S) measurement is proposed as an acceptable method after a suitable calibration for the study of compositional and structural (phase related) factors, to determine a level of heat treating or even the level of internal stress state in engineering alloys. We are focusing on to determine the influence of various Ni content in FeNi alloy system both in amorpus and in crystalline state. We also define the influence of mechanical and surface stress from the point of view of thermopower. The results of thermoelectric power measurements reported in this paper do confirm the applicability of S (T) measurements in the determination of compositional effects and mapping the stress state in different type of engineering alloys.