I. Bednarczyk

Study of Microstructure of the Al-Fe Alloys After Hot Rolling Deformation

The aim of the paper is a microstructure analysis of alloys from the Al-Fe system after hot rolling tests, conducted by using a scanning transmission electron microscopy STEM and scanning electron microscope equipped with EBSD detector. Hot rolling was carried out at Technical University of Ostrava, Faculty of Metallurgy and Material Engineering, Institute of Modelling and Control of Forming Processes. The samples were heated to a temperature of \(1200\,^{\circ }\)C. The EBSD and STEM techniques have been applied in order to determine the influence of chemical composition and deformation parameters on structural changes. The microstructure analysis has included parameters such us: grain/sub-grain size, area fraction of grains/subgrains, misorientation angles, grains/subgrains shape aspect ratio and dislocations structure. The research structure techniques in scanning-transmission electron microscopy revealed numerous FeAl28 alloy phase separations of secondary nucleating sites favoured energetically, which are the boundary of grains/subgrains and dislocations. These changes in the structure of the test results have been confirmed by EBSD, which revealed the presence of grains/subgrains misorientation angle boundaries above \(15^{\circ }\).

The influence of thermo-mechanical treatment on the structure and plasticity of FeAl intermetallic phase–base alloy

Alloys based on intermetallic phases from the Fe-Al system they belong to a group of high-temperature creep resisting materials of advantageous physicochemical and mechanical properties at an elevated and high temperature. In general, limitation on the capacity for a broad application of intermetals from the Fe-Al system, e.g. as an alternative to expensive alloy steels of specific properties, is their insufficient plasticity, which is a factor inhibiting further their development as constructional materials. Under this study, research has been conducted on the capacity for forming alloys based on intermetallic phases from the Fe-Al system, via thermo-mechanical processing. In the present work, the possibility of forming Fe-Al-intermetallic-phase-based alloys in thermo-mechanical treatment (TMT) has been studied. After casting and annealing, alloy specimens were subjected to axial-symmetric compression in the Gleeble 3800 simulator in the range of 700–1200 °C at 0.01, 0.1, 1.0, 10 s −1 strain rates. In order to analyze the processes which take place during deformation, the specimens after deformation were intensely cooled with water. Structural examination was carried out using light and electron microscopy. The impact of hot rolling process parameters on the structure of intermetallic-phase-based FeAl alloys and properties has been determined. The results will constitute the basis for modelling the structural changes in FeAl intermetallic alloy.

Sonochemical growth of nanomaterials in carbon nanotube

HighlightsParameters of sonochemical encapsulation of SbSI and SbSeI in CNTs.SbSI@CNTs and SbSeI@CNTs bonded ultrasonically with microelectrodes.200% increase of conductance due to ultrasonic bonding of filled CNTs to Au.SbSI@CNTs and SbSeI@CNTs gas sensors do not require heating system for recovery.SbSI@CNTs structures applied to detect carbon dioxide. ABSTRACT Recent achievements in investigations of carbon nanotubes (CNTs) filled with ternary chalcohalides (antimony sulfoiodide (SbSI) and antimony selenoiodide (SbSeI)) are presented. Parameters of sonochemical encapsulation of nanocrystalline semiconducting ferroelectric SbSI‐type materials in CNTs are reported. This low temperature technology is convenient, fast, efficient and environmentally friendly route for producing novel type of hybrid materials useful for nanodevices. Structure as well as optical and electrical properties of SbSI@CNTs and SbSeI@CNTs are described. Advantages of ultrasonic joining of such filled CNTs with metal microelectrodes are emphasized. The possible applications of these nanomaterials as gas sensors are shown.

The Microstructure of AlSi7Mg Alloy in as Cast Condition

The complex microstructure of as-cast AlSi7Mg alloy has been investigated. Microstructure observations were done using light microscopy, scanning electron microscopy and transmission electron microscopy. Chemical composition of the microstructure constituents was investigated by means of energy dispersive spectrometry, conducted both during SEM and STEM investigations. Selected area diffraction was used to identify the phases in the alloy. Microstructure of the alloy in the as-cast condition consists of Al-Si eutectic and intermetallic phases in the interdendritic regions. These are: Mg2Si, α-AlFeMnS, β-AlFeSi and π-AlFeSiMg phases. What is more, number of fine precipitates were found within the α-Al dendrites. Only the occurrence of U1 (MgAl2Si2) phase has been confirmed.

Antimony Sulfoiodide as Novel Material for Photonic Crystals

Semiconducting ferroelectrics promise construction of crystals with tuned photonic band gap. Such structures were synthesized by self-assembling SiO2 spheres, followed by melt infiltration with antimony sulfoiodide and the removal of SiO2 spheres by chemical etching.

Structural Characterization of FeAl28Cr5 Alloy Deformed in the Hot Torsion Process

Current research in the field of iron aluminides are directed towards to understand the structural phenomena occurring during plastic deformation of these alloys. The obtained results of the study and collected informations will be used to determine the description of the structural changes taking place during hot deformation of Fe ̶Al alloys. The article presents the results of the study of the alloy FeAl28Cr5 deformed by hot torsion in temperature range of 800÷1100°C and a strain rate of 0.1 s-1. The analysis of the structure of the alloy FeAl28Cr5 allowed to reveal changes caused by dynamic processes of deformation. The results of torsion tests show the possibility to obtain a fine-grained structure with of parameters of the processes (T=1000°C, 1100°C) and strain of ε=40. After deformation at strain of (ε=40) the structure consists of fine grains with a misorientation angle higher than 15°, and the average grain size diameter D=28.5 micrometers. Deformation at a temperature of T=1000°C and 1100°C is accompanied by superplastic flow effect.

Plasticity and Microstructure of Hot Deformed Magnesium Alloy AZ61

The article presents the results of tests connected with the influence of strain parameters on the change of flow stress and microstructure of magnesium alloy AZ61 (symbol according to ASTM norms). Test of uniaxial hot compression were conducted in temperature range from 250 to 400°C and the strain speed from 0.01 to 1 s-1. Analysis of plastometric tests and microstructure observation allowed to establish which mechanism - slip or twinning – is dominant in particular conditions of shaping AZ61 alloy. Achieved results were compared with previous results achieved for AZ31 alloy type with lower content of aluminium.

Structure and Properties of Steel Welding after Micro-Jet Cooling Process

Welding with micro-jet cooling is an innovate technology. It is possible to get structure of weld metal deposit (WMD) with a very high amount of acicular ferrite (on the level of 70 %) that is not valuable for other processes. It corresponds with good impact toughness of weld. In the paper parameters of micro-jet cooling and mechanical structure of weld will be present and compared with welding without micro-jet cooling. Results of investigation are very optimistic. That technology should be treated for welding of other materials.

Influence of deformation parameters on the structure in selected intermetallic from Al-Fe diagram

Department of Materials Science at Silesian University of Technology since 10 years conducts researches to learn about the structural phenomena which occur during hot plastic treatment which are aimed at elaboration of a technology of heat and plastic treatment of selected alloys from Al-Fe diagram. The iron aluminides have been among the most widely studied intermetallics because their low cost, low density, good wear oxidation and corrosion resistance, to create wide prospects for their industrial applications, for components of machines working at a high temperature and in corrosive environment. The problem limiting their application is low plasticity and brittle cracking susceptibility. Consequently, the research of intermetallic-phase based alloys focuses on their plasticity. For the development of thermo-plastic treatment technology, it is necessary to determine internal variables describing the structure of an alloys being deformed is the inhomogeneity, grain size, as well as the grains misorientation angles and texture. The paper presents the course of structural changes of Fe-38Al with Zr, B Mo and C additions under the influence of hot plastic deformation with application of a few different temperatures of the process with given speed of deformation. For the structure and substructure investigations were used a light microscopy and transmission electron microscopy.