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Microstructural characterization of welded joints in Zr-based amorphous metallic alloys

Grant number: 17/10052-9
Support type:Scholarships in Brazil - Master
Effective date (Start): September 01, 2017
Effective date (End): February 29, 2020
Field of knowledge:Engineering - Materials and Metallurgical Engineering - Physical Metallurgy
Principal Investigator:Marcelo Falcão de Oliveira
Grantee:Carolina Soares
Home Institution: Escola de Engenharia de São Carlos (EESC). Universidade de São Paulo (USP). São Carlos , SP, Brazil
Associated research grant:13/05987-8 - Processing and characterization of amorphous, metastable and nano-structured metallic alloys, AP.TEM
Associated scholarship(s):18/12960-2 - Microstructural characterization of bulk metallic glass welded interfaces by TEM, BE.EP.MS

Abstract

Some metallic alloys when solidified at the critical cooling rates show amorphous structure, instead of traditional metals, whose structure is crystalline. The first developed metallic glass required cooling rates higher than 105 K / s, for these reason only micrometer thicknesses were obtained. With the advancement of the researches, alloys with a greater tendency to glass formation were developed and thus bulk metallic glasses (BMG), whose amorphous thicknesses were greater than 1 mm, could be produced. Currently, these materials have structural, electronic, medical applications and in the aerospace and defense industries. However, there are still limitations to its use, one of which is its low weldability. In general, in the welding of the VMM the mechanical strength of the joint is impaired by the formation of crystals due to the thermal input. Thus, the study of the influence of welding parameters on the welded joints microstructure plays a fundamental role in the expansion of the BMG application. In the present project, the goal is the microstructural characterization of the welded joints and their correlation with the welding parameters used. For this, techniques such as optical microscopy, scanning electron microscopy, X-ray diffraction and differential scanning calorimetry will be used. In addition, for the most relevant samples, advanced microscopy techniques will be used, such as transmission electron microscopy with convergent beam to characterize the present phases and the focused ion beam technique in order to verify the presence of particles, Oxide or other defects that prevent effective metallurgical bonding. This stage of the work should be developed abroad (BEPE) under the co-orientation of Prof. Michael J. Kaufman of the Colorado School of Mines, a specialist in transmission electron microscopy and is already working on a partnership with the research group.