Processing and Characterization of Open–Cell Aluminum Foams Obtained through Infiltration Processes

AbstractThis work reports the fabricating of open–cell Al foams which were manufactured through infiltration processes employing a device with controlled atmosphere for the fusion and infiltration processes of the metal, which is separate from the heating furnace. The device allows controlling its internal atmosphere with an inert gas to protect the metal of the fast oxidation, avoiding the employment of a controlled atmosphere furnace (a furnace of this kind incorporate the heating and the control atmosphere systems itself). The metal used for the present study was Al in ingot form with 99.8% purity. Equiaxial NaCl granules in three ranges of particle sizes were chosen as space holder particles (SHP). The range I from 4.7 to 4.0mm, the range II from 4.0 to 3.3mm, and the range III from 3.3 to 2.0mm. The obtained foams showed a highly porous structure with interconnected cells in all cases. The maximum porosity and minimum density values resulted to be ∼73.7% and ∼0.71g/cm3, respectively. This work demonstrates that it is possible to use NaCl with different particle sizes in the manufacturing of Al foams with high porosity, low density and roughly 100% interconnected cells employing a device with controlled atmosphere and an electrical furnace, both separated from one another. The results are interpreted in terms of NaCl particle sizes and its content in the samples

Magnetization dynamics and magnetoimpedance effect of novel Fe-B-Si-M (M = Ta, Y) amorphous wires

Amorphous wires of composition Fe64Co8B 19.2Si4.8M4 (M = Ta, Y) and 140 μm of diameter were obtained by rotating-water-bath-melt-spinning technique. Saturation magnetization (Ms) and coercivity values (Hc), at room temperature, were in the range of 1 T and 31 A/m, respectively, for the Ta samples, and Ms = 1.32 T and Hc = 109 A/m, respectively, for the Y samples. The magnetic permeability as a function of frequency showed a domain wall relaxation character, with relaxation frequency, of 3.5 kHz and 9 kHz for the Ta and the Y compounds, respectively. Magnetoimpedance (MI) measurements exhibited a MI factor ΔZ/Z0 = 11% for the Ta alloys, and 41% for the Y alloys. Results are interpreted in terms of magnetoelastic coupling differences in both alloys caused by distinctive frozen-in stresses for each case during the fabrication process. Copyright © 2013 American Scientific Publishers All rights reserved.Peer Reviewe

Low-field magnetization process and complex permeability of FeCoBSiTa wires coated with hard magnetic CoNi layer

Biphase wires consisting of a soft magnetic amorphous nucleus surrounded by a hard magnetic CoNi layer of variable thickness were obtained by means of rotating water-quenching method and subsequent electroplating technique. Magnetization processes for all the biphase wires were resolved in terms of reversible bulging of magnetic domains and spin rotation by means of complex permeability measurements within the frequency range of 10 Hz-13 MHz. Results are interpreted in terms of CoNi layer effect on the magnetic anisotropy of the soft core. © Indian Academy of Sciences.Acknowledges the scholarship granted by DGEP-UNAM. (IB) acknowledges the financial support from Research Grant IN106808 PAPIIT-UNAM.Peer Reviewe