Development of GBD (grain boundary diffusion) processes for coercivity enhancement of rare-earth permanent magnets

• Grant number: 14/27196-5
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: August 01, 2015
• End date: February 15, 2016
• Field of knowledge: Engineering - Materials and Metallurgical Engineering - Physical Metallurgy
• Agreement: Coordination of Improvement of Higher Education Personnel (CAPES)
• Principal Investigator: Hidetoshi Takiishi
• Grantee: Leonardo Ulian Lopes
• Host Institution: Instituto de Pesquisas Energéticas e Nucleares (IPEN). Secretaria de Desenvolvimento Econômico (São Paulo - Estado). São Paulo , SP, Brazil

Abstract

Rare earth-based supermagnets require significant additions of the element Dy (dysprosium) for applications at elevated temperatures, e.g. in hybrid and electric vehicles. The high price and scarcity of this element motivate the search for new addition techniques to minimize its content in magnets, while keeping their magnetic characteristics. The development of new processes for introducing Dy via Gain Boundary Diffusion (GBD) has been suggested in the literature as a promising method, but the current diffusion technique - starting from the magnet's surface - presents technical limitations regarding the microstructural modification depth. The aim of this research project is to investigate new techniques that promote the GBD process through internal diffusion, which pursues to introduce Dy during the conventional magnet manufacturing process, mixed with the main alloy powder and making use of heat treatments to control the diffusion. What is proposed here would provide major benefits such as facilitated industrial implementation and the possibility of producing thicker magnets, bypassing limitations imposed by the reduced depth of diffusion of GBD techniques previously reported in the literature. (AU)