FeB and FeBC-based multicomponent alloys coatings with optimized compositions and microstructures for corrosion and wear resistance.

• Grant number: 24/22545-3
• Support Opportunities: Regular Research Grants
• Start date: July 01, 2025
• End date: June 30, 2028
• Field of knowledge: Engineering - Materials and Metallurgical Engineering - Physical Metallurgy
• Principal Investigator: Walter José Botta Filho
• Grantee: Walter José Botta Filho
• Host Institution: Centro de Ciências Exatas e de Tecnologia (CCET). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil
• Associated researchers: Guilherme Yuuki Koga ; Guilherme Zepon ; Lucas Barcelos Otani

Abstract

FeB and Fe(BC)-based amorphous alloys and the microstructures resulting from partial crystallization of these alloys, can present a unique combination of properties of great interest for applications in coatings that simultaneously require high resistance to corrosion and wear, as in the case of numerous components in the chemical and petrochemical industry. Among the various Fe systems that have alloys with good glass forming ability, the Fe-Cr-Nb-B system had a special interest in our group, since several amorphous alloys with excellent corrosion resistance can be produced from commercial precursors. However, in alloys containing Fe-B, the desired increase in wear resistance with the controlled crystallization for borides formation is accompanied by deterioration of the good corrosion properties associated with the amorphous phases. The optimization of corrosion and wear properties in the condition of partial crystallization depends on the understanding of the crystallization mechanisms as a function of the alloy composition, mainly trying to avoid excessive partitioning of solute during the initial stages of crystallization. Such a situation has already been observed in new families of multicomponent alloys, where the formation of borides is inhibited with the initial formation of a solid solution with a composition close to the amorphous matrix, avoiding the intense redistribution of solute and the formation of Cr-depleted zones, thus reducing the degradation of corrosion properties. The unique microstructure, composed of an amorphous matrix containing multicomponent nanometric crystals, ccc or cfc solid solutions, basically of the same composition as the matrix, ensures the compromise and optimization of the tribological and electrochemical properties, desired in coatings subjected to severe corrosion and wear conditions. In this project we will use alloys of the Fe-Cr-Nb-M-B and Fe-Cr-Nb-M-BC systems, being M one or combination of the elements Mo, Mn, Co, Ni, W and Y, with compositions already studied in our group, and eventually to be optimized, to produce coatings by thermal spray and laser cladding. The alloys and coatings will be evaluated in all stages of alloy production and processing, with calorimetric, structural and microstructural characterization. Also, the mechanical, corrosion and wear properties will be evaluated by traditional electrochemical and tribological techniques. (AU)