Oxygen influence evaluation in crystalline phases induction in amorphous metal alloys

• Grant number: 16/17444-7
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: November 01, 2016
• End date: October 31, 2017
• Field of knowledge: Engineering - Materials and Metallurgical Engineering - Transformation Metallurgy
• Principal Investigator: Marcelo Falcão de Oliveira
• Grantee: Wesley Marques de Paula
• Host Institution: Escola de Engenharia de São Carlos (EESC). Universidade de São Paulo (USP). São Carlos , SP, Brazil

Abstract

Bulk metallic glasses have gained more attention as promising materials due to their properties, which, in many cases, are superior to the same ones in traditional crystalline alloys. However, some difficulties to produce them that complicate the obtainment of alloys longer than a few centimeters still exist, limiting their application and enhancing their cost of production. The latests studies aimed to improve the glass forming ability of these alloys, in order to make possible obtain BMGs using lower cooling rates. It was observed that the GFA is highly dependent on the alloy composition and on the atmosphere in which the melting process occur as well. This dependency is evidenced when the influence of oxygen content is studied. It is known that oxygen cause induce crystalline phase nucleation, in other words, it decreases the GFA, in most cases. In this perspective, this project has the objective of producing samples of Zr and Ti based alloys, containing different percentages of oxygen content and samples with the addition of rare earth metals. Their influence will be evaluated by measuring the maximum amorphous fraction found in the samples and the addition of the rare earth elements will be correlated with the different levels of oxygen contamination. The samples will be produced in the system developed on the project subsidized by FAPESP, process number 2006/00675-4. This system is composed by an electric arc furnace, whose atmosphere can be controlled by using a vacuum pump and argon injections. The alloys will be impelled into casting molds, with different geometries by pressure drop. The samples characterization will be done by X-ray diffraction, optical microscopy and scanning electron microscopy, and by EDS. For that purpose, the samples will first suffer the proper metallographic preparation. (AU)