UNDOPhase: UNcertainty-DOminated Phase Transitions in Magnetic Materials
Abstract
Ferromagnetic materials are extensively used in magneto-mechanical devices, such as sensors, motors, generators, and transformers, owing to their strong permanent magnetic features. The most important physical mechanism that drastically impacts the permanent magnetic properties of ferromagnets is the phase transition from the ferromagnetic to the paramagnetic phase at the critical (Curie) temperature. However, the ferromagnetic paramagnetic phase transition is not only driven by temperature but is also driven by interactions among external fields and magnetic spins. Our experimental understanding of the phase transition is not unique because of the measurement uncertainties inherent in the external fields and ambient temperature. These uncertainties cause variations in the transition onset by propagating through the free energy and magnetization of the system. Therefore, the phase transition occurs at a range of critical external field and temperature values, which defines the transition zone. It is vital to control the transition zone to maintain the safety in critical applications of interest to the Air Force, including the design of high-technology magnets and rare-Earth element components for F-22 and F-35 fighter jets. Existing knowledge about the determination of the transition zone is based on simplified analyses, as the comprehensive effects of the long-range interactions among the magnetic spins, external parameters, and uncertainties have been neglected. The PI proposes to determine the ferromagnetic-paramagnetic phase transition onset and quantify the likelihood of the transition by examining: i) high-order interactions between the magnetic spins and external fields; ii) long-range effects including the grain boundaries and dislocations; iii) propagation of the uncertainties in external fields and temperature. With this project, the underlying physical mechanisms behind the phase transitions will be quantitatively investigated. This will lead to the robust control and design of magneto-mechanical devices in extreme environments with the elimination of the failure risks associated with the loss of permanent magnetic properties.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jan 21, 2022
- Source ID
- FA95502110120XX0
Entities
People
- Pınar Acar
Organizations
- Air Force Office of Scientific Research
- United States Air Force
- Virginia Tech