Wyznaczenie resztkowej energii sprężystej oraz energii rozpraszanej podczas odwracalnej przemiany martenzytycznej w stopie Ni52,2Mn21,3Ga26,5

In this paper we present results of an analysis of the influence of annealing time on the residual pseudo-chemical energy and dissipative energy Fdis(z) during reversible martensitic transformation. Analysis was performed without equilibrium temperature and basis on the model proposed in the study: (LIKHACHEV 1998). From designated courses of residual non-chemical and pseudo-chemical dissipative energies come, that carried thermal treatment causes significant changes of them. Immediately after casting the studied alloy shows continuous increase of the dissipative energy with increasing of martensite fraction. After annealing at the time from 1-0 h, curves Fdis(z) have a curse close to constant function whereas beyond this range show dynamic increasing or decreasing of dissipation energy.W pracy przedstawiono wyniki przeprowadzonej analizy wpływu czasu wygrzewania próbek stopu Ni52,2Mn21,3Ga26,5 na resztkową energię sprężystą oraz energię dyssypowaną Fdis(z) podczas odwracalnej przemiany martenzytycznej. Analizę przeprowadzono z pominięciem temperatury równowagi fazowej na podstawie modelu zaproponowanego w pracy LIKHACHEVA (1998). Z wyznaczonych przebiegów zmian resztkowej energii sprężystej oraz energii rozpraszanej wynika, że przeprowadzona obróbka termiczna powoduje znaczne ich zmiany. W stanie bezpośrednio po wytopie badany stop wykazuje ciągły wzrost energii rozpraszanej wraz ze wzrostem zawartości frakcji martenzytu. Po zastosowaniu wygrzewania w czasach 1-20 h, krzywe Fdis(z) mają przebieg zbliżony do funkcji stałej, natomiast poza nim wykazują dynamiczny wzrost bądź spadek energii dyssypowanej

Characteristics of porous beds based on fractal parameters

The paper presents the results of a fractal analysis of the cross-sections of a porous mineral deposit consisting of spherical elements which formed a spatial system with varying porosity (0.4 to 0.95). The virtual deposit was generated using the Discrete Element Method in the YADE code by means of the so-called Radius Expansion Method. The fractal analysis was carried out using the structure function method, determining the fractal dimension (D), the topothesy (L) and the corner frequency (l) (MAINSAH et al. 2001). The conducted simulations have confirmed to a considerable extent the test results available in the literature involving the fractal analysis of mineral deposits with varying porosity. They clearly indicate that the fractal dimension does not change along with the porosity of the deposit, if the autocorrelation function or their transformations (e.g. structure function) methods are used. Moreover, based on the information available in the literature, it can be concluded that the value of the fractal dimension corresponds to mineral deposits with the specified geometric shapes of the elements which form them

A Comparison between Contact and Tapping AFM Mode in Surface Morphology Studies

The paper presents recent results from studies of a surface topography of a platinum calibration grid on silicon substrate obtained in both contact and tapping modes of the AFM microscope. The results are analyzed in order to determine the influence of the scan set-up and the SPM probe onto estimated fractal parameters and surface anisotropy ratio

Changes in magnetic domain structure of maraging steel studied by magnetic force microscopy

The paper presents results on whether and how the magnetic domain structure in maraging steel undergoes any change due to the aging process. It continues the works on application of correlation methods and fractal analysis into studies of magnetic properties of various steel alloys using Scanning Probe Microscopy. It is aimed at verifying the usefulness of the structure function for description of spatial changes in shape and orientation of magnetic domains, and the magnitude of magnetic stray field affected by the heat treatment. Obtained results suggest that despite vanishing magnetic tip-surface interaction, and hence vanishing magnetic stray field, magnetic domains remain nearly perfectly isotropic although randomly oriented. Similar to isotropic real surfaces, the fractal dimension of the magnetic domains turns out to be independent of the structural changes induced by the aging process, whereas the topothesy is found to vary within order of magnitude along with changes in the magnetic stray field. After all, obtained results lead to conclusion that the aging process leaves its fingerprints in the structure of the steel alloys, which can be studied using numerical analysis of images of magnetic interactions between vibrating tip and the stray field

Structural studies of welds in wear-resistant steels

The work presents results of the research on changes in microstructural, and mechanical properties of the structural XAR 400 wear-resistant steel caused by the welding procedure. Metallographic and microhardness studies revealed complex microstructure of the welds that turned out to vary with the distance from the weld axis: predominance of the acicular ferrite (ACF) structures in the weld itself, quasi-polygonal ferrite (QPF) crystals with precipitates of troostite (T) in the heat-affected zone, and the bainitic ferrite (BF) structures in the heat-partially-affected zone

Functional and Fractal Properties of Fe-Al Coatings After Gas Detonation Spraying (GDS)

The paper presents the results and provides an analyse of the geometric structure of Fe-Al protective coatings, gas-treated under specified GDS conditions. The analysis of the surface topography was conducted on the basis of the results obtained from the SEM data. Topographic images were converted to three-dimensional maps, scaling the registered amplitude coordinates of specific gray levels to the relative range of 0÷1. This allowed us to assess the degree of surface development by determining the fractal dimension. At the same time, the generated three-dimensional spectra of the autocorrelation function enabled the researchers to determine the autocorrelation length (Sal) and the degree of anisotropy (Str) of the surfaces, in accordance with ISO 25178. Furthermore, the reconstructed three-dimensional images of the topography allowed us to evaluate the functional properties of the studied surfaces based on the Abbott-Firestone curve (A-F), also known as the bearing area curve. The ordinate describing the height of the profile was replaced by the percentage of surface amplitude in this method, so in effect the shares of the height of the three-dimensional topographic map profiles of various load-bearing properties were determined. In this way, both the relative height of peaks, core and recesses as well as their percentages were subsequently established

Zastosowanie funkcji autokorelacji oraz geometrii fraktalnej do analizy obrazów struktur domenowych rejestrowanych metodą MFM

Presented work is focused on the use of correlation methods for numerical analysis of magnetic stray field over the surface of materials. Obtained results extend our previous findings about application of the autocorrelation function and the fractal analysis for characterization of magnetic surfaces. Several domain images are recorded at various tip-sample gaps (i.e. the lift heights), and then their average widths were extrapolated down to the zero distance in order to estimate the width seen right on the surface. Apart from that, fractal parameters were derived from autocorrelation function, which turned out to be sensitive to the lift height, and might constitute universal measure (the critical lift height), above which the MFM signal became dominated by thermal noises and non-magnetic residual interactions.Niniejsza praca dotyczy zastosowania metod korelacyjnych do numerycznej analizy obrazów rozkładu pola magnetycznego emitowanego z obszarów spontanicznego namagnesowania. W pracy przedstawiono kontynuację badań nad zastosowaniem funkcji autokorelacji oraz metod analizy fraktalnej w badaniach struktury domenowej oraz charakterystyki emitowanego z nich pola magnetycznego. Wyniki badań wykazują zależność mierzonej metodami mikroskopii sił magnetycznych (MFM) szerokości domen od wysokości skanowania nad badaną powierzchnią, sugerując przeprowadzanie serii pomiarów na różnych wysokościach (h), ich aproksymację z następną ekstrapolacją do powierzchni (h=0). Przeprowadzona analiza fraktalna, wskazuje na możliwość jej aplikacji do charakterystyki zmian sygnału magnetycznego rejestrowanego przez MFM. Pozwala ona również na wyznaczenie wysokości krytycznej (hkr), na której sygnałem dominującym stają się nakładające się na sygnał magnetyczny pozostałości niemagnetycznych interakcji między igłą sondy i badaną powierzchnią, stanowiące rejestrowany przez MFM szum

Application of Fractal Analysis Methods for Lift Height Optimization in Magnetic Force Microscopy Measurements

The paper presents results of a research on simulation of magnetic tip-surface interaction as a function of the lift height in the magnetic force microscopy. As expected, magnetic signal monotonically decays with increasing lift height, but the question aris es, whether or not optimal lift height eventually exists. To estimate such a lift height simple procedure is proposed in the paper based on the minimization of the fractal dimension of the averaged profile of the MFM signal. In this case, the fractal dimension ser ves as a measure of distortion of a pure tip-surface magnetic coupling by various side effects, e.g. thermal noise and contribution of topographic features. Obtained simulation results apparently agree with experimental data

Wpływ procesu wytwarzania stali X2CrNiMoN25-7-4 na jej budowę strukturalną

This paper presents results of X2CrNiMoN25-7-4 steel structure investigation. Measurements were carried out in commercial state and after additional solution heat treatment. The structure analysis was carried out based on XRD measurements. Obtained results allowed for determination of structure parameters, phase's volume and lattice defects. Obtained results suggested, that applied finishing treatments didn't influent on structure parameters and the lattice defects.W pracy przedstawiono wyniki badań struktury stali X2CrNiMoN25-7-4. Badania przeprowadzono dla stanu komercyjnego materiału oraz po procesie powtórnego przesycania. Strukturę materiału analizowano na podstawie pomiarów dyfraktometrycznych. Określono parametry sieciowe składników, stopień zdefektowania struktury oraz wyznaczono udziały fazowe. Analiza wyników badań wykazała, że stosowane na etapie produkcji zabiegi wykańczające nie wpłynęły na parametry strukturalne oraz stopień zdefektowania struktury