Numerical analysis of AZ61 magnesium alloy extrusion process by modified equal channel angular extrusion (ECAE) method

The paper presents the results of numerical modelling of AZ61 magnesium alloy hot deformation using modified ECAE method. The temperature-velocity conditions were analysed using FEM. The extrusion process was realised using the die with modified angular channel containing horizontal contracting zone in the material exit direction. The channels were arranged at right angle relatively to each other. The main aim of the numerical research was to determine the most favourable parameters of the extrusion that allow obtaining the products with good mechanical properties. The final product is a round rod that could be used as a material charge to further plastic deformation process

On the surface critical behaviour in Ising strips: density-matrix renormalization-group study

Using the density-matrix renormalization-group method we study the surface critical behaviour of the magnetization in Ising strips in the subcritical region. Our results support the prediction that the surface magnetization in the two phases along the pseudo-coexistence curve also behaves as for the ordinary transition below the wetting temperature for the finite value of the surface field.Comment: 15 pages, 9 figure

Analysis of the Thermal and Magnetic Properties of Amorphous Fe 61Co10Zr2.5Hf2.5Me2W2B20 (Where Me = Mo, Nb, Ni Or Y) Ribbons

The paper presents the results of structural and magnetic properties and thermal stability for a group of functional materials based on Fe61Co10Zr2.5Hf2.5Me2W2B20 (where Me = Mo, Nb, Ni or Y). Samples were obtained in the form of ribbons using melt-spinning method. The X-ray diffraction patterns of investigated samples confirmed their amorphous structure. Based on the analysis of DSC curves characteristic temperatures: glass forming temperature (Tg), crystallization temperature (Tx) and temperature range of the supercooled liquid ΔTx were determined. Small addition of transition metals elements has strong influence on magnetic and thermal parameters of studied materials. The comprehensive studies revealed that in terms of magnetic properties the Ni-addition resulted in highest reduction in coercivity and anisotropy field

AusTraits, a curated plant trait database for the Australian flora

We introduce the AusTraits database - a compilation of values of plant traits for taxa in the Australian flora (hereafter AusTraits). AusTraits synthesises data on 448 traits across 28,640 taxa from field campaigns, published literature, taxonomic monographs, and individual taxon descriptions. Traits vary in scope from physiological measures of performance (e.g. photosynthetic gas exchange, water-use efficiency) to morphological attributes (e.g. leaf area, seed mass, plant height) which link to aspects of ecological variation. AusTraits contains curated and harmonised individual- and species-level measurements coupled to, where available, contextual information on site properties and experimental conditions. This article provides information on version 3.0.2 of AusTraits which contains data for 997,808 trait-by-taxon combinations. We envision AusTraits as an ongoing collaborative initiative for easily archiving and sharing trait data, which also provides a template for other national or regional initiatives globally to fill persistent gaps in trait knowledge

Effect of structural relaxations within the amorphous structure on the magnetic properties of amorphous tapes from FeCoB family

The paper presents the research results for the Fe78Co2Si9B11 amorphous alloy, and after the process of annealing resulting only in the relaxation of the material. The structure relaxations occurring in the volume of test samples lead to the changes in their magnetic and mechanic properties. Therefore the studies on the effect of the structure defects on the properties of these type of materials are important. Understanding the processes occurring during the magnetizing of amorphous alloys can be helpful in the design of modern functional materials for special purposes. The main purpose of this elaboration was to determine the effect of the amorphous structure defects in the state after solidification and after heat treatment on the changes in the magnetizing process and in such parameters as the saturation magnetization and the coercivity field

Wpływ nieznacznego dodatku kobaltu na właściwości magnetyczne oraz źródła naprężeń wewnętrznych w postaci wolnych objętości oraz pseudodyslokacyjnych dipoli w stopach Fe78CoXSi11-XB11 (x = 0 Or 2)

Amorphous materials in the form of tapes, despite being discovered more than half a century ago, are still the object of interest for materials engineers and electro-technical industry. They possess a great application potential, and are constantly studied for new variations. Due to the different structure from the commonly manufactured textured FeSi sheets, FeCoB based amorphous alloys demonstrate very good, so called soft magnetic properties. This paper presents the results of studying the structure and magnetic properties of tapes of Fe78CoxSi11-xB11 (X = 0 or 2) alloys of amorphous structure. In addition, the effect of Co alloy addition on the type of structural defects in the area of ferromagnetic saturation approach was examined. It was found that a small addition of Co affects the increase of saturation magnetization value, as well as the distribution of magnetization vectors within the stresses sources in form of structure defects.Materiały amorficzne w postaci taśm pomimo, że zostały odkryte już ponad pól wieku temu cały czas są obiektem zainteresowania inżynierów materiałowych i przemysłu elektrotechnicznego. Posiadają one ogromny potencjał aplikacyjny i stale poszukiwane są nowe ich odmiany. Ze względu na odmienną strukturę, niż w powszechnie produkowanych teksturowanych blachach FeSi, stopy amorficzne na bazie FeCoB posiadają bardzo dobre tzw. właściwości magnetycznie miękkie. W pracy przedstawiono wyniki badań struktury oraz właściwości magnetycznych dla taśm stopów Fe78CoxSi11-xB11 (x = 0 lub 2) o strukturze amorficznej. Ponadto, zbadano wpływ dodatku stopowego Co na rodzaj defektów strukturalnych w obszarze podejścia do ferromagnetycznego nasycenia. Stwierdzono, że niewielki dodatek Co wpływa na podniesienie wartości magnetyzacji nasycenia oraz rozkład wektorów magnetyzacji w obrębie źródeł naprężeń w postaci defektów struktury

Influence of mechanical activation and heat treatment on surface development and oxide layer thickness of Ti6Al4V ELI alloy

Purpose: The paper presents the results of mechanical activation of the surface on oxide layer thickness after heat treatment of TU6Al14V ELI alloy. Design/methodology/approach: Specimens were made from 5 mm diameter rod cut into semicircular slices. The samples were mechanically activated throughout mechanical treatment of the surface: one sandblasted with glass beads during 5 minutes and other ground with sandpaper grit 40, 180, 220 and 800 during 7.5 and 15 minutes. Findings: Then microstructure of specimens etched with Kroll solution was observed using an optical microscope and roughness parameters of the surface were measured. Research limitations/implications: Afterwards heat treatment (550°C, 5 hours) was conducted, then roughness parameters and thickness of the oxide layer were measured by means of a scanning microscope. Practical implications: The conducted research showed up that mechanical activation of the surface which cause an increase of surface development results in greater thickness of the oxide layer which is formed during heat treatment. Nevertheless, mechanical activation that results in a decrease of surface development, such as polishing, results in a decrease of oxide layer thickness. Originality/value: The results of the research can be used to obtain the desired thickness of the oxide layer in the production of the elements that require increased wear and corrosion resistance

Influence of preparation method and storage of samples for evaluation of pozzolanic and hydraulic activity of fly ash

W artykule przedstawiono wyniki badań aktywności hydraulicznej popiołów lotnych wapniowych oraz aktywności pucolanowej popiołów lotnych krzemionkowych, stosowanych do spoiw drogowych i mieszanek związanych spoiwem hydraulicznym, określonych w normie PN-EN 14227-4. Badaniom poddane były wybrane popioły reprezentujące konwencjonalne popioły lotne ze spalania węgla kamiennego i brunatnego. Określony został wpływ sposobu przygotowania i przechowywania prób na urabialność mieszanki oraz na uzyskane wartości wytrzymałości na ściskanie (aktywność hydrauliczna lub pucolanowa).Article describes research result of hydraulic activity of calcareous fly ash and pozzolanic activity of siliceous fly ash used for hydraulically bound mixtures specified in norm PN-EN 14227-4. The conventional fly ashes from the combustion of coal and lignite were tested. The impact of the methods of preparation and storage of the samples, on the workability of the mixture and the resulting compressive strength values (hydraulic activity or pozzolanic activity) were determined

Ocena struktury oraz właściwości magnetycznych stopów amorficznych Fe73Me5Y3B19 (gdzie Me = Ti lub Nb)

The results of microstructure and magnetic properties studies of the amorphous Fe73Me5Y3B19 (where Me = Ti or Nb) alloys are presented The samples of the investigated alloys were produced in the form of ribbons with thickness of approximately 30 um by unidirectional cooling of the liquid material on a rotating copper wheel. Both investigated alloys, in the as-quenched state, were fully amorphous which was verified using a ‘Bruker’ X-ray diffractometer. Static hysteresis loops, measured using ‘LakeShore’ vibrating sample magnetometer (VSM), were typical as for soft magnetic ferromagnets. The Fe73Nb5Y3B19 and Fe73Ti5Y3B19 alloys were characterized by relatively high values of saturation of the magnetization (1.25 T and 1.26 T, respectively) and low coercivity field (16 A/m and 47 A/m, respectively). The core losses obtained for the investigated alloys were significantly lower than for commercially used FeSi transformer steels. Both alloys also exhibited excellent time and temperature stability of the magnetic properties (within the investigated temperature range), as confirmed by measurements of magnetic susceptibility and its disaccommodation.Celem pracy było zbadanie mikrostruktury oraz właściwości magnetycznych czteroskładnikowych stopów Fe73Me5Y3B19 (gdzie Me = Ti lub Nb) o strukturze amorficznej, otrzymanych techniką ultraszybkiego zestalania ciekłego stopu na miedzianym obracającym się bębnie. Strukturę odlanych taśm badano za pomocą dyfraktometru rentgenowskiego firmy "Bruker". Z pomiarów tych wynika, że obydwa czteroskładnikowe stopy w stanie po odlaniu były amorficzne. Statyczne pętle histerezy zmierzone przy użyciu magnetometru wibracyjnego (VSM) firmy "LeakeSchore", były typowe jak dla ferromagnetyków magnetycznie miękkich, a wytworzone stopy Fe73Nb5Y3B19 i Fe73Ti5Y3B19 cechowały się względnie wysoką magnetyzacją nasycenia (odpowiednio: 1.25 T i 1.26 T) i małym polem koercji (odpowiednio: 16 A/m i 47 A/m). Straty energii potrzebnej na jeden cykl przemagnesowania dla obydwu badanych stopów były znacznie mniejsze niż dla komercyjnie produkowanych stali transformatorowych FeSi. Wytworzone stopy wykazywały dobrą stabilność czasową oraz temperaturową właściwości magnetycznych (w wyznaczonym zakresie temperatur), któwą określono na podstawie pomiarów podatności magnetycznej i jej dezakomodacji