Optimization of the piezomagnetic properties of Fe-Al-B alloys for use in the force actuators and sensors

Author(s)

Mateus Botani de Souza Dias

• Document type: Doctoral Thesis
• Press: Lorena.
• Institution: Universidade de São Paulo (USP). Escola de Engenharia de Lorena
• Defense date: 18 set. 2017

Examining board members

Cristina Bormio Nunes; Antonio Jefferson da Silva Machado; Clara Johanna Pacheco; Antonio Domingues dos Santos

• Advisor: Cristina Bormio Nunes

Abstract

Magnetostrictive materials, like TERFENOL-D (Tb0.27-0.30Dy0.73-0.70Fe2) and GALFENOL (Fe72-82Ga18-28), are applied in several types of sensors, actuators and energy harvesting. Nevertheless, there is the necessity of new materials that are cheaper, environmentally friendly and with good mechanical properties. For that reason, the Fe-Al alloys are an alternative, since the aluminum is more abundant in nature and is seven times cheaper than gallium. The goal of this work is to study the influence of two thermomechanical proceeding at magnetic properties of the (Fe1- xAlx)98.4B1.6 alloys, which x = 0.18; 0.13 e 0.21. At the first proceeding, the alloys were submitted to a stress annealing to introduce an extrinsic magnetocrystalline anisotropy. Up to 180 MPa of compression stress, stress annealed alloys have magnetostriction and piezomagnetic coefficient values higher than the alloys without annealing. In other words, this proceeding increased the alloys sensibility to be applied like actuators (d33) and sensors (d33 *). At the second thermomechanical proceeding, samples with sheet format were rolled and annealed to induce an abnormal grain growth and, consequently, a texture. Although the annealing not produced an abnormal grain growth, the magnetostriction values are higher than for the as-cast samples. Both proceedings were efficient to improve the magnetic properties and the (Fe0.87Al0.13)98.4B1.6 alloy achieved the higher values of magnetostriction and piezomagnetic coefficient. In another words, between the studied alloys, this composition was the most promising to be applied like actuators and sensors. (AU)

• FAPESP's process: 14/16872-0 - Optimization of the piezomagnetic properties of Fe-Al-B alloys for use in the force sensors
• Grantee: Mateus Botani de Souza Dias
• Support type: Scholarships in Brazil - Doctorate