Clara Johanna Pacheco

Magnetomechanical behavior of a directly solidified Fe-Al-B alloy

Textural analysis of a Fe–Al–B alloy obtained by directional solidification indicates an average direction of solidification of 〈310〉, close to 〈100〉. The magnetomechanical behavior is characterized by the sensing and actuation sensitivities and respectively. The Fe2B phase does not act as a pinning center against domain wall movement, proved by the achieved reversible thermodynamic condition. This phase also does not degrade the saturation magnetization of the alloy, because it has a high saturation magnetization of 1.5 T. Relatively high sensitivities of 13 kA m−1 MPa−1 were obtained for very low fields of ~4 kA m−1, the same magnitude as that obtained in rare earth based materials, but for much lower fields. The good formability and machining properties of the Fe–Al–B alloy are also of benefit compared to rare earth based materials.

Evaluation of Non-destructive Techniques (Thermography, Ultrasound and Eddy Current) for Detection of Failures in Metallic Substrates with Composite Anticorrosive Coatings

The aim of this study is to evaluate the ability of three nondestructive techniques—ultrasound, thermography and eddy current—for the detection of defects that can occur in metallic substrate with anticorrosive coating and compare the results regarding the advantages and disadvantages of each one of these inspection techniques. For this study, samples were made from a metallic substrate in which a composite anticorrosive coating and two types of defects were introduced: localized corrosion (defects of different geometries and depths inserted into the metallic substrate) and adhesion failure between the coating and the substrate. According to the results, all three techniques showed to be able to detect defects simulating localized corrosion on the substrate. However, the adhesion failure was only effectively detected by thermography and ultrasound and a high correlation between these two techniques was observed.