ASTACIO LÓPEZ , Raquel

Se estudia la fabricación de núcleos magnéticos amorfos (destinados principalmente a motores y transformadores eléctricos) mediante una nueva técnica consistente en: (1) obtención de partículas ferromagnéticas amorfizadas mediante molienda mecánica y (2) consolidación eléctrica mediante el proceso denominado SRE de dichas partículas para...

Se ha aplicado un método novedoso para aumentar la dureza de una aleación de aluminio y titanio partiendo de polvo amorfo obtenido mediante molienda mecánica de alta energía y posterior consolidación mediante sinterización por resistencia eléctrica. Los polvos amorfos de TiAl, fabricados mediante molienda mecánica durante 75 horas, mostraron...

In this work, the obtaining of amorphized ferromagnetic particles by mechanical milling has been studied. For this purpose, the compositions Fe₇₈Si₂₂ and Fe₇₈Si₉B₁₃ have been studied and the results have been compared in order to determine the best characteristics achieved with this technique. The behavior has been studied when other elements...

In this work, the obtaining of amorphized ferromagnetic particles by mechanical milling has been studied. For this purpose, the compositions Fe₇₈Si₂₂ and Fe₇₈Si₉9B₁₃ have been studied and the results have been compared in order to determine the best characteristics achieved with this technique. The behavior has been studied when other elements...

Se ha fabricado polvo amorfo de la aleación Al75Fe25 a partir del polvo elemental cristalino de aluminio puro y hierro puro. El proceso de fabricación del polvo amorfo se ha llevado a cabo mediante molienda mecánica con una duración de hasta 100 horas. El objetivo de este trabajo consiste en determinar la evolución de la compresibilidad y de la...

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The present work aims to produce TixCu100-x (x = 90, 80, 70, and 60) amorphous alloys by using high energy ball mill. The microstructure and possible formation of amorphous phases were characterized employing laser granulometry, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The...

Capacitor electrical discharge consolidation (CEDC) is a technique that uses the heat of the Joule effect of a high intensity electric current to consolidate powders. In this study, the effect of the precompaction pressure and the number of discharges on the porosity, microstructure and hardness of the compacts is analysed. Furthermore, the...

Ti-Cu alloys are used in dental and medical applications, due to their good mechanical properties, corrosion resistance and antibacterial properties. These properties are sensitive to microstructure and can be improved by formation of intermetallic compounds or amorphization of crystalline Ti-Cu powder. This study focuses on the amorphization...

The crystallization process, both at the initial and subsequent stages, of amorphous Al88-RE4-Ni8 alloys (RE = Y, Sm and Ce) has been studied. Additionally, the consequences of adding 1 at.% Cu replacing Ni or Al were studied. The stability of the amorphous structure in melt spun ribbons was thermally studied by di erential scanning...

Medium-frequency electrical resistance sintering (MF-ERS) is a technique that uses the application of pressure and heat, heat coming from the Joule effect, simultaneously to metallic powders. In this study, this technique consolidates commercial iron powders, and the porosity distribution and hysteresis curves of the compacts were analysed....

In this paper, electrical-discharge-consolidation (EDC technique) experiments were carried out with an equipment based on the technology developed for the stud welding technology. The main advantage of the EDC technique is its high speed, on the order of milliseconds or less, which makes it particularly interesting when a high final porosity is...

In manufacturing processes using powder metallurgical methods, one of the most important and most expensive parts is consolidation and subsequent conventional sintering. Electrical discharge sintering (EDS) is a manufacturing process that converts the two steps of consolidation and conventional sintering into a single step. Additionally, the...

A commercially pure (c.p.) nickel powder was consolidated by Medium-Frequency Electrical Resistance Sintering (MF-ERS). In this consolidation technique, a pressure and the heat released by a high-intensity and low-voltage electrical current are concurrently applied to a metal powder mass. A nickel powder with a high tap porosity (86%) and a low...

The technique of sintering by electrical discharge of capacitors (SEDC) is investigated, using a commercial stud welding equipment adapted to be used in the sintering of amorphous powders. In this technique, pressure and the heat generated by the Joule effect from the high intensity electric current are applied simultaneously to a mass of...

The technique of sintering by electrical discharge of capacitors (SEDC) is investigated, using a commercial stud welding equipment adapted to be used in the sintering of amorphous powders. In this technique, pressure and the heat generated by the Joule effect from the high intensity electric current are applied simultaneously to a mass of...

The influence of the applied pressure and electrical parameters on the macrostructure of specimens consolidated by the medium-frequency electrical resistance sintering technique (MF-ERS) is analysed in this work. This technique is based on the application of pressure to a mass of conductive powder that, simultaneously, is being crossed by a...

The fabrication of soft magnetic Fe parts by the medium-frequency electrical resistance sintering (MF-ERS) technique is studied in this paper. This consolidation technique involves the simultaneous application to metallic powders of pressure and heat, the latter coming from the Joule effect of a low-voltage and high-intensity electric current....

The aim of this work is to study the viability of producing, by medium-frequency electrical resistance sintering (MF-ERS), compacts from mechanically alloyed aluminium powders. The MF-ERS process was carried out using different values of current intensity (6, 8, 10 and 11 kA) and dwelling (heating) times (400, 700 and 1000 ms). Results were...

The unique combination of hardness, toughness and wear resistance exhibited by WC-Co cemented carbides (hardmetals) has made them a preeminent material choice for extremely demanding applications, such as metal cutting/forming tools or mining bits, in which improved and consistent performance together with high reliability are required. The...

In this paper, a phenomenological model to predict the value of the electrical resistance of a compressed metal powder mass is proposed. The model, based on the experimental compressibility and resistivity-porosity curves, is useful in the field of the electrical resistance consolidation. In this area is often required to find out whether a...

Commercially pure (C.P.) iron powders with a deliberate high degree of oxidation were consolidated by medium-frequency electrical resistance sintering (MF-ERS). This is a consolidation technique where pressure, and heat coming from a low-voltage and high-intensity electrical current, are simultaneously applied to a powder mass. In this work,...

Aluminum matrix composites (AMCs) reinforced by aluminum nitride were prepared by mechanical alloying followed by a simple press and sintering method. Milling began under vacuum and after a period of between 1 and 4 h, NH3 gas flow (1 cm3/s) was incorporated until the total milling time of 5 h was reached. Results show that in addition to the...

In this paper, the process known as Electrical Resistance Sintering under Pressure is modelled, simulated and validated. This consolidation technique consists of applying a high-intensity electrical current to a metallic powder mass under compression. The Joule efect acts heating and softening the powders at the time that pressure deforms and...