An austempering study of ductile iron alloyed with copper

Austempered ductile iron (ADI) has proved to be an excellent material as it possesses attractive properties: high strength, ductility and toughness are combined with good wear resistance and machinability. These properties can be achieved upon adequate heat treatment which yields the optimum microstructure for a given chemical composition. In this paper the results of an investigation the austempering of ADI alloyed with 0.45 % Cu for a range of times and temperatures are reported. The microstructure and fracture mode developed throughout these treatments have been identified by means of light and scanning electron microscopy and X-ray diffraction analysis. It was shown that the strength, elongation and impact energy strongly depend on the amounts of bainitic ferrite and retained austenite. Based on these results, and optimal processing window was established

Label-free smartphone quantitation of bacteria by darkfield imaging of light scattering in fluoropolymer micro capillary film allows portable detection of bacteriophage lysis

Conventional methods for the detection and quantitation of bacteria are slow, laborious and require a laboratory. Microfluidic systems offer faster and portable testing, and smartphone cameras can record colorimetric or fluorometric bioassays, but this requires dye addition. Here, we demonstrate for the first time label-free smartphone detection of bacterial light scattering by darkfield microfluidic imaging to measure bacteria and bacteriophage lysis. A single LED and portable 3D printed imaging box allowed bacterial concentration and growth to be measured by direct imaging of bacterial light scattering. Bacteriophage lysis was detected within a 10-channel microfluidic device made from melt-extruded fluoropolymer micro capillary film, allowing rapid detection of host specificity. Elimination of unwanted reflections and optimising illumination angle are critical for successful darkfield bacterial imaging, with 15° giving maximal intensity. Bacterial sedimentation was directly observed within microfluidic devices, and detection sensitivity significantly increased by allowing bacteria to sediment for 30 min. With this simple, low-cost, 3D printed system bacterial concentrations down to an optical density of 0.1 could be measured corresponding to 8 × 104 colony forming units (CFU) per microdevice, approaching the sensitivity of conventional spectrophotometers. Bacteriophage lysis could be detected at a range of starting cell concentrations. With a low starting cell concentration, the increase in light scatter signal with incubation was prevented in the presence of bacteriophage. Conversely, with high starting cell concentration, the light scatter signal detected at the start was clearly eliminated when phage were added, indicating this simple system allows direct visualisation of bacteriophage eliminating light scattering by lysis

Austempering study of unalloyed and alloyed ductile irons

Austempered ductile iron (ADI) proved to be an advanced material as it possesses remarkable combination of high strength, ductility and toughness with good wear resistance and machinability. These properties can be achieved upon adequate heat treatment which yields optimum microstructure for a given chemical composition. In the present paper, an investigation has been conducted on unalloyed ADI and alloyed with 0.47%Cu and 1.6%Cu + 1.5%Ni, austempered at 350 degrees C for the time up to the 6 h. The microstructure and fracture mode developed throughout these treatments have been studied by means of light, transmission and scanning electron microscopy, as well as X-ray diffraction. It was shown that the strength, elongation and impact energy strongly depend on amount of ausferritic ferrite and stable, high carbon enriched retained, reacted austenite. Based on the results, optimal processing windows for alloyed ductile irons used, have been established. In addition, for alloyed ADIs with maximum amount of reacted, retained austenite, transition temperature was also obtained

The austempering study of alloyed ductile iron

Austempered ductile iron (ADI) proved to be an excellent material as it possesses attractive properties: high strength, ductility and toughness are combined with good wear resistance and machinability. These properties can be achieved upon adequate heat treatment which yields optimum microstructure for a given chemical composition. In this paper an investigation has been conducted on ADI alloyed with 0.45%Cu and austempered in a range of times and temperatures. The microstructure and fracture mode developed throughout these treatments have been identified by means of light and scanning electron microscopy and X-ray diffraction analysis. It was shown that strength, elongation and impact energy strongly depend on amounts of bainitic ferrite and retained austenite. Based on these results an optimal processing window has been established. (C) 2004 Elsevier Ltd. All rights reserved

Solutions of Critical Raw Materials Issues Regarding Iron-Based Alloys.

The Critical Raw Materials (CRMs) list has been defined based on economic importance and supply risk by the European Commission. This review paper describes two issues regarding critical raw materials: the possibilities of their substitution in iron-based alloys and the use of iron-based alloys instead of other materials in order to save CRMs. This review covers strategies for saving chromium in stainless steel, substitution or lowering the amounts of carbide-forming elements (especially tungsten and vanadium) in tool steel and alternative iron-based CRM-free and low-CRM materials: austempered ductile cast iron, high-temperature alloys based on intermetallics of iron and sintered diamond tools with an iron-containing low-cobalt binder

Microstructural and mechanical properties of Ti3Al-based intermetallics produced by powder metallurgy

The structural and compression mechanical properties of Ti3Al-based intermetallics produced by powder metallurgy techniques have been studied. The as-milled powders were compacted by hot pressing to non-porous homogenous compacts. Prior to compression tests, all compacts were homogenized by a solution treatment at 1050 degrees C (alpha+beta region) for 1h, followed by water quenching. The compression tests were performed from room temperature to 500 degrees C in vacuum at a strain rate of 2.4 x 10(-3) s(-1). Detailed microstructural characterization was evaluated by scanning electron microscopy (SEM), followed by energy dispersive spectroscopy (EDS) and X-ray diffraction analysis.Current Research in Advanced Materials and Processes, 6th Conference of the Yugoslav-Materials-Research-Society, Sep 13-17, 2004, Herceg Novi, Montenegr

Abrasive wear behaviour of ADI material with various retained austenite content

In this paper, the wear rate of ferritic and pearlitic ductile iron, as well as three types of austempered ductile iron (ADI materials), austempered at 300, 350 and 400 degrees C is investigated. Two wear parameters were varied, wear load (0.5, 1.3, 2 kg) and grit paper abrasive grain size (P240, P500, P800). The hardness of ductile iron and stress-assisted phase transformation of retained austenite into martensite (SATRAM) phenomenon in ADI materials were found to play major roles in wear behaviour. The pronounced SATRAM phenomenon was detected for the most severe wear parameters. Another important factor in the occurrence of SATRAM phenomenon is the presence of metastable, low carbon-enriched retained austenite. As a consequence, the wear rate of ADI austempered at 400 degrees C is nearly equivalent to ADI austempered at 300 degrees C at medium and high loading with the coarsest abrasive paper grit tested (P240)

Abrasive wear behaviour of ADI material with various retained austenite content

In this paper, the wear rate of ferritic and pearlitic ductile iron, as well as three types of austempered ductile iron (ADI materials), austempered at 300, 350 and 400 degrees C is investigated. Two wear parameters were varied, wear load (0.5, 1.3, 2 kg) and grit paper abrasive grain size (P240, P500, P800). The hardness of ductile iron and stress-assisted phase transformation of retained austenite into martensite (SATRAM) phenomenon in ADI materials were found to play major roles in wear behaviour. The pronounced SATRAM phenomenon was detected for the most severe wear parameters. Another important factor in the occurrence of SATRAM phenomenon is the presence of metastable, low carbon-enriched retained austenite. As a consequence, the wear rate of ADI austempered at 400 degrees C is nearly equivalent to ADI austempered at 300 degrees C at medium and high loading with the coarsest abrasive paper grit tested (P240)

Microstructural and mechanical properties of Ti3Al-based intermetallics produced by powder metallurgy

The structural and compression mechanical properties of Ti3Al-based intermetallics produced by powder metallurgy techniques have been studied. The as-milled powders were compacted by hot pressing to non-porous homogenous compacts. Prior to compression tests, all compacts were homogenized by a solution treatment at 1050 degrees C (alpha+beta region) for 1h, followed by water quenching. The compression tests were performed from room temperature to 500 degrees C in vacuum at a strain rate of 2.4 x 10(-3) s(-1). Detailed microstructural characterization was evaluated by scanning electron microscopy (SEM), followed by energy dispersive spectroscopy (EDS) and X-ray diffraction analysis.Current Research in Advanced Materials and Processes, 6th Conference of the Yugoslav-Materials-Research-Society, Sep 13-17, 2004, Herceg Novi, Montenegr

Changes of hydrogen storage properties of MgH2 induced by heavy ion irradiation

In order to understand the influence of defect zones on desorption behavior of MgH2, Xe 120 keV ion irradiation of this material has been performed. DSC, SEM measurements, and SRIM calculations have been used to characterize induced modifications and its influence on the hydrogen desorption behavior of MgH2. We have demonstrated that the near-surface area of MgH2 plays the crucial role in hydrogen desorption kinetics. DSC analysis provides clear picture of vacancies influence on H diffusion and desorption in MgH2, and points out that there is possibility to control the thermodynamic parameters by controlled ion bombardment. (C) 2008 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved