Péter János Szabó

High pressure torsion of amorphous Cu60Zr30Ti10 alloy

High pressure torsion was applied to produce a disk-shaped specimen of Cu60Zr30Ti10 composition. The dependence of the morphology, microstructure, and thermal behavior on the applied shear strain was monitored by scanning and transmission electron microscopies, synchrotron x-ray diffraction, and calorimetry. The disk consists of a gradient microstructure ranging from large homogeneous blocks (about 20 μm) to finely dispersed nanocrystals (about 20 nm) of two stable hexagonal phases and continuously decreasing amorphous content with increasing strain. The evolution of such microstructure was interpreted by using a model based on heat conduction generated by the extensive shear deformation.

Bimodal Grain Size Distribution Enhances Strength and Ductility Simultaneously in a Low-Carbon Low-Alloy Steel

Low-carbon low-alloy steel specimens were quenched, then cold rolled, and finally annealed. Electron backscatter diffraction (EBSD) micrographs revealed a bimodal grain structure where ultra-fine grain structures with low-angle grain boundaries are alternating with regions of larger grains. The average total dislocation density was measured by X-ray line profile analysis, whereas the geometrically necessary dislocation density was obtained from the analysis of EBSD data. Using the combination of the Hall–Petch and Taylor equations, a good correlation was found between the total dislocation density and the measured flow stress in the different states of the alloy. The difference in evolutions of the total and the geometrically necessary component of the dislocation densities is discussed in terms of the successive processes of quenching, rolling, and annealing of the alloy.

EDS-Analysis of Intermetallic Precipitation in Thermally Aged SAF 2507 Type Superduplex Stainless Steel

Due to thermal ageing several precipitation and segregation processes occur in austenitic-ferritic superduplex stainless steel. During phase transformation processes mostly intermetallic compounds, and-due to the high solved nitrogen content-nitrides appear. These changes in microstructure influence the two original phases (the ferrite and austenite) in different way. Thermal ageing was performed on SAF 2507 steel in a broad thermal interval. Changes in microstructure were followed by scanning electron microscopy and energy-dispersive X-ray spectroscopy. The concentration of small particles was determined by successively decreasing of accelerating voltage, corrected by a factor, which was determined by large-area measurements.

Radon and thoron levels, their spatial and seasonal variations in adobe dwellings – a case study at the great Hungarian plain

Radon and thoron isotopes are responsible for approximately half of the average annual effective dose to humans. Although the half-life of thoron is short, it can potentially enter indoor air from adobe walls. Adobe was a traditional construction material in the Great Hungarian Plain. Its major raw materials are the alluvial sediments of the area. Here, seasonal radon and thoron activity concentrations were measured in 53 adobe dwellings in 7 settlements by pairs of etched track detectors. The results show that the annual average radon and thoron activity concentrations are elevated in these dwellings and that the proportions with values higher than 300 Bq m−3 are 14–17 and 29–32% for radon and thoron, respectively. The calculated radon inhalation dose is significantly higher than the world average value, exceeding 10 mSv y−1 in 7% of the dwellings of this study. Thoron also can be a significant contributor to the inhalation dose with about 30% in the total inhalation dose. The changes of weather conditions seem to be more relevant in the variation of measurement results than the differences in the local sedimentary geology. Still, the highest values were detected on clay. Through the year, radon follows the average temperature changes and is affected by the ventilation, whereas thoron rather seems to follow the amount of precipitation.

Effect of grain orientation on chemical etching

The effect of grain orientation on the effectiveness of pre-etching before color etching was investigated by the help of electron back scattering diffraction and atomic force microscopy in case of cast iron. Strong correlation was found between the angle between the specimen normal and the [001] orientation of the ferrite grains and the depth of the etching. If the angle between the specimen normal and the [001] direction of the ferritic grain is small, then the speed of the etching is low, but the lateral variation of the etching speed within the grain is larger.

Correlation between the Grain Orientation Dependence of Color Etching and Chemical Etching

A gray cast iron specimen was investigated by color and chemical etching with optical and atomic force microscopy, and the effect of grain orientation on the effectiveness of etching was examined. It was proven that the grain orientation dependence of chemical and color etching is just the opposite, and that the specimen surface after color etching is not uniformly smooth. Explanation for the layer structure of the color etched iron specimen is given.

High pressure torsion of Cu-based metallic glasses

Cu-Zr-Ti metallic glass was subjected to high pressure torsion applying different revolution times (180s, 120s, 60s). Both deformation and deformation rate dependent microstructural and thermal properties were characterized by scanning electron microscopy, X-ray diffraction and calorimetry, respectively. In order to estimate the temperature rise in the metallic glass during high pressure torsion, quasi three-dimensional heat conduction equation with a source term was considered. Solutions indicate that the saturation temperature strongly depends on the revolution time, i. e. on the deformation rate.

Improving the ISO prolog standard by analyzing compliance test results

Part 1 of the ISO Prolog standard (ISO/IEC 13211) published in 1995 covers the core of Prolog, including syntax, operational semantics, streams and some built-in predicates. Libraries, DCGs, and global mutables are current standardization topics. Most Prolog implementations provide an ISO mode in which they adhere to the standard. Our goal is to improve parts of the Prolog standard already published by finding and fixing ambiguities and missing details. To do so, we have compiled a suite of more than 1000 test cases covering part 1, and ran it on several free and commercial Prolog implementations. In this study we summarize the reasons of the test case failures, and discuss which of these indicate possible flaws in the standard. We also discuss test framework and test case development issues specific to Prolog, as well as some portability issues encountered.

EDS Investigation of Fe–Al intermetallic compounds

Steels are often coated with other metallic materials to obtain better surface properties. In several cases this layer is made by hot dip methods. ()wing to the concentration gradient between the base metal and the layer, phase transformations occur in the diffusive interface layer. These phase transformations, of course, influence the kinetics of the coating process and the properties of the coating itself. The aim of this work was to clarify the characteristic features of the aluminium coating process in connection with the phase transformations in the diffusive interface layer. The development of the compound layer, its microstructure and phases were investigated in order to determine the effect of the carbon content of the base metal.

Correlation between microstructural evolution during high-pressure torsion and isothermal heat treatment of amorphous Al85Gd8Ni5Co2 alloy

þ a-Al phase mixture to primary a-Al by increasing the annealingtemperature above 555 K. This thermal sensitivity predestinates the composition toidentify the controversial thermal contribution of the plastic deformation in metallicglasses. Thermal stability and structure of the partially devitrified samples weresystematically analyzed and compared by calorimetry, x-ray diffraction, and electronmicroscopy. It seems that the effect of severe deformation cannot be singled out by asimple isothermal heat treatment; i.e., high-pressure torsion acts as a spectrum of heattreatments performed at different annealing temperatures.I. INTRODUCTIONAmorphous Al-based aluminum–transition-metal–rare-earth alloys (Al–TM–RE) have successfully beensynthesized over a wide composition range in the lastdecades.