Recrystallization Behavior of Commercial Purity Aluminium Alloys

Recrystallization behavior of commercial purity aluminium alloys has been explained elaborately with different steps, process parameters and microstructural examination

Alloy Development through Rapid Solidification for Soft Magnetic Application

This chapter describes different rapidly solidified processing routes of soft magnetic alloys and their properties and applications in different areas. Section-2 explains the details of process mechanism. The functions of different alloying elements are discussed with the alloy design of soft magnetic alloys in section-3. The structure-property correlation is described in section-4. Section-5 highlights different types of rapidly solidified soft magnetic alloys, like high permeability alloys, high induction alloys, Fe-6.5 wt% Si steel and GMI alloys. In the last section-6, the applications of different types of soft magnetic alloys are mentioned

Bulk Metallic Glasses and Nanostructured Materials

There is always a requirement for materials having higher performance than the existing one without any extra cost or even paying less. Demands ofhigh performance materials are increasing to improve the efficiency oftheproducts and produce micro-components for various applications. The polycrystalline materials prepared in conventional melting casting route have almost reached to its highest perfor-mance level. Hence, newerprocessing techniques are being adopted to develop newer materials so that the component should have smooth surface finish, minimum shrinkage etc. Excellent fillability and imprintability are prime requir-ements for the production of good quality micro-precision parts. In this regard, metallic glasses have achieved much attention due to its superior properties compared to the crystalline materials of same composition. The metallic glass can be prepared through rapid solidification techni-que where liquid metal can be poured on the surface of a rapidly rotating Cu-drum. In this process the cooling rate of the materials become 106K/s and the materials are obtai-ned in the form of about 30p,m thick ribbon, which is amorphous in nature. The isotropic nature of the material becomes immediate curiosity for functional applications, in particular Fe, Co and Ni based materials for magnetic application

Accounting for the effect of heterogeneous plastic deformation on the formability of aluminium and steel sheets

Forming Limit Curves characterise ‘mean’ failure strains of sheet metals. Safety levels from the curves define the deterministic upper limit of the processing and part design window, which can be small for high strength, low formability materials. Effects of heterogeneity of plastic deformation, widely accepted to occur on the microscale, are neglected. Marciniak tests were carried out on aluminium alloys (AA6111-T4, NG5754-O), dual-phase steel (DP600) and mild steel (MS3). Digital image correlation was used to measure the effect of heterogeneity on failure. Heterogeneity, based on strain variance was modelled with the 2-component Gaussian Mixture Model and a framework was proposed to 1) identify the onset of necking and to 2) re-define formability as a probability to failure. The result were ‘forming maps’ in major-minor strain space of contours of constant probability (from probability, P=0 to P=1), which showed how failure risk increased with major strain. The contour bands indicated the unique degree of heterogeneity in each material. NG5754-O had the greatest width (0.07 strain) in plane strain and MS3 the lowest (0.03 strain). This novel characterisation will allow engineers to balance a desired forming window for a component design with the risk to failure of the material

Crystallization kinetics and giant magneto impedance behavior of FeCo based amorphous wires

The effects of Nb addition on crystallization kinetics and giant magneto impedance (GMI) properties of Fe39Co39Si8B14 amorphous wires prepared by in-water quenching system have been investigated. Thermal behaviors of the wires have been investigated by thermal electrical resistivity measurement and differential scanning calroimetry. The substitution of 4 at% Nb for Fe and Co increases crystallization temperature and merges two crystallization peaks into one peak, leading to a significant increase in thermal stability against crystallization for Fe37Co37Nb4Si8B14 wire. The formation of Fe2Nb phase due to addition of Nb increases the activation energy for crystallization from 425 to 550 kJ/mol. The GMI properties of the alloys are evaluated at driving current amplitude of 10 mA and a frequency of 400 kHz. The alloys show the single peak behavior in the GMI profile. The change in GMI properties increases from 10% at 0 at% Nb to 25% at 4 at% Nb

Microstructural evolution, recovery and recrystallization kinetics of isothermally annealed ultra low carbon steel

The recovery and recrystallization kinetics of 80%cold rolled ultra low carbon steel are investigated during isothermally annealing for temperature ranges 350–640 °C as a function of different annealing time. The recovery is assessed by magnetic coercivity (Hc),while the recrystallization is determined by mechanical hardness.At low temperature (350 to 520 °C) annealing, recovery dominates for long time (∼12 000 s),while the annealing at 550 °C/ 900s and 580 °C/ 300s causes the recrystallized nuclei formation . The recovery kinetics is introduced by differential rate equation, explaining the reduction in coercivity with the recovery progress and the variation of an activation energy from41–113 kJmol−1. The recrystallization kinetics is found faster at high annealing temperature 640 °C than 550 and 580 °C based on hardness measurement, justifying by apparent activation energy within 114–190 kJ/mol. Furthermore, the recovery and recrystallization rate increase with different annealing time, consistent to the change of microstructures and grain boundary characteristics evaluated by the orientation imaging microscopy (OIM) of electron backscattered diffraction (EBSD)

Giant Magnetoimpedance Sensor for Structural Integrity Assessment of Engineering Components

Investigation is focused on the development of sensor based on giant magnetoimpedance (GMI) effect using soft magnetic Co66Fe2Si13B15Cr4 amorphous wire as sensing (core) element. The GMI property of the sensing element was utilized for fabrication of the sensor which is sensitive to the minute variation of the local magnetic field. The sensor output signal is calibrated with respect to external applied magnetic field and the sensitivity is found to be 56.11 mV/µT. The sensor shows a good linear response and its repeatability and reproducibility are observed to be satisfactory. The sensor is very much useful for detection of the localized magnetic field of service exposed engineering components within an external magnetic field using GMI sensor, and more specifically, to develop a GMI sensor for efficient monitoring of structural integrity of engineering components. The conventional non-destructive techniques like ultrasonic, eddy current, magnetic particle inspection are very useful to identify the defects or cracks. However, these methods are unsuitable for monitoring structural degradation. Since most of the structural components used in the industry are of ferromagnetic steel, the microstructural properties of the components due to their long service period influence the magnetic and mechanical properties. Therefore, the developed sensor could be used to detect the local magnetic field of the aging structure which changes with the microstructure of the component and thereby, assessing the integrity of the components

Development of GMI Based Sensing Device for Identification of Magnetic Phases in Steel

A giant magnetoimpedance (GMI) sensor based on CoFeSiBCr soft magnetic amorphous microwire of diameter 100 µm as a sensing element has been developed and the performances of the GMI sensor are carefully studied. The sensor measures the phase shift of the modulated signal in terms of voltage using balanced modulator/demodulator topology which has been calibrated in terms of localized magnetic field. The sensor shows a good linear response with the magnetic field. It has been tested at different conditions and repeatable of data has been observed. The sensitivity of the sensor has been observed to be 0.12 mV/Am-1. The sensor can be used to identify various magnetic phases in semi finished steel products. For an example, in duplex stainless steel where the material has austenite and ferrite components, the developed sensor can be utilized for the evaluation of volume fraction of each phase. Similarly, in 304 SS which undergoes stress induced martensite transformation can also be evaluated using the developed sensor

Glass forming ability and soft-magnetic properties of Fe-based glassy alloys developed using high phosphorous pig Iron

Glass forming ability (GFA) and soft-magnetic behaviour of melt-spun Fe69C5.5P11.5Mn0.4Si2.3Cr1.8Mo1B8.5 (alloy 2) and Fe68C9P12Mn1Si3Nb2B5, (alloy 3) alloys prepared using high phosphorous pig iron (h-PI, Fe80C14P2.2Mn0.4Si3.4) has been studied. The glass formation, thermo-physical and soft-magnetic properties of the alloys were analyzed for different quenching rates by varying wheel speed as 23, 26, 33, 39 and 43 m/s. The simultaneous incorporation of alloying elements (Cr, Mo, Nb) and metalloids (C, B, P, Si) transforms h-PI to complete glassy alloy, even at low quenching rates. The melt quenching rate influences the thermal parameters and Curie temperature of glassy ribbons in an opposite way. Amongst all, FeCPMnSiCrMoB glassy alloy show superior combination of higher glass transition temperature of 788 K, super cooled region of 34 K, glass Curie temperature of 552 K, coercivity less than 13 A/m and maximum saturation magnetization of 1.1 T. In addition, the annealing treatment at 758 K improves magnetic softness (1.7 A/m) of the alloy by relaxation of quenched-in stresses. The comparison of developed glassy alloy with similar Fe-glassy alloys and SENNTIX type alloys show best combination of thermo-physical and magnetic properties. The glassy alloy prepared using blast furnace high phosphorous pig iron can be used for uniformly gapped soft-magnetic cores

Corrigendum: Topical Ophthalmic Formulation of Trichostatin A and SurR9-C84A for Quick Recovery Post-alkali Burn of Corneal Haze

Alkali burn injury is a true ocular emergency of the conjunctiva and cornea that requires immediate precision. Lack of an immediate therapy can lead to a substantial damage in the ocular surface and anterior segment further causing visual impairment and disfigurement. We explored the regenerative capability of dominant negative survivin protein (SurR9-C84A) and histone deacetylase inhibitor trichostatin-A (TSA) in vivo, in a rat alkali burn model. A topical insult in rat eyes with NaOH led to degradation of the conjunctival and corneal epithelium. The integrity of the conjunctival and corneal tissue was increased by TSA and SurR9-C84A by improving the clathrin and claudin expressions. Wound healing was initiated by an increase in TGF-beta-1 and, increased endogenous survivin which inhibited apoptosis post-TSA and SurR9-C84A treatments. Protein expressions of fibronectin and alpha-integrin 5 were found to increase promoting corneal integrity. The cytokine analysis confirmed increased expressions of IL-1beta, IL-6, IL-12, IL-13, IFN-gamma, TNF-alpha, GMCSF, Rantes, and MMP-2 in injured cornea, which were found to be significantly downregulated by the combined treatment of SurR9-C84A and TSA. The ocular and systemic pharmacokinetic (PK) parameters were measured post-topical ocular administration of TSA and SurR9-C84A. The SurR9-C84A and TSA sustained relatively longer in the cornea, conjunctiva, and aqueous humor than in the tear fluid and plasma. Our results confirmed that a combination of TSA with SurR9-C8A worked in synergy and showed a promising healing and anti-inflammatory effect in a very short time against alkali burn. Therefore, a combination of TSA and SurR9-C84A can fulfill the need for an immediate response to wound healing in alkali burnt cornea. We also synthesized ultra-small chitosan nanoparticles (USC-NPs) targeted with alpha-SMA antibodies that can be used for delivery of TSA and SurR9-C84A specifically to the ocular burn site