Banca de QUALIFICAÇÃO: PÂMELLA RAFFAELA DANTAS DE FREITAS

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
STUDENT : PÂMELLA RAFFAELA DANTAS DE FREITAS
DATE: 18/05/2023
TIME: 10:00
LOCAL: Sala de Reuniões – LIME, 2° Piso
TITLE:

Sn-Ag-Sb Alloys: Analysis of Solidification and Market Scenario

KEY WORDS:

Solidification; Sn-Ag-Sb alloys; Microstructure; Thermal Parameters; marketing scenario.

PAGES: 131
BIG AREA: Engenharias
AREA: Engenharia de Materiais e Metalúrgica
SUBÁREA: Metalurgia Física
SPECIALTY: Transformação de Fases
SUMMARY:

The use of lead-containing alloys (Pb) in electronic microcomponents is a technological and environmental issue that requires urgent and attention. In this context, the development of new alloys with similar or superior properties to Pb-containing alloys is an alternative. Furthermore, the Fourth Industrial Revolution brought new production possibilities, with the creation of new materials improving properties such as lightweight, better mechanical properties, adaptability and with recyclability characteristics. The 4.0 paradigm demands eco-friendly solutions and the new lead-free alloys are the best alternatives to meet this new window of opportunity. The Sn-Ag alloys have promising properties such as good mechanical strength and creep resistance, but they have low toughness, problems with silver segregation and low wetting on metallic substrates. In this context, the present study aims to analyze the effect of antimony (Sb) additions (0.2 and 2.0% in weight) on the microstructure, thermal parameters of solidification (cooling rate-Ṫ_L and growth rate-V_L), phase transformation temperatures, macrosegregation, mechanical properties and fracture modes in the hypoeutectic Sn-2.0wt.%Ag alloy directionally solidified under transient conditions. The microstructural and mechanical characterization occurred through the use of techniques such as Optical Microscopy (OM), Scanning Electron Microscopy (SEM), X-Ray Fluorescence (XRF), X-Ray Diffraction (XRD), Vickers microhardness and tensile tests. Thermodynamic calculations were performed by Thermocalc software, in order to study the evolution of phase fractions and solidification paths. In addition, an analysis of the market scenario in which the Sn-Ag-Sb alloys are inserted was carried out, through prospects on the Espacenet platform and desk research. The microstructures of Sn-Ag-Sb alloys are completely dendritic with an Sn-rich matrix (β-Sn) surrounded by a eutectic mixture, β-Sn+Ag₃Sn+SbSn. The Sb additions promoted a microstructural refinement and a slight increase in liquidus and solidus temperatures, when compared to the binary alloy Sn-2wt.%Ag. Ag exhibited a constant and higher than nominal macrosegregation profile, while Sb changed from a constant profile to an inverse type with increasing Sb content. The Ag₃Sn intermetallic displayed two morphologies, fibrous and spherical, with prevalence of the latter for Ṫ_L>5.10 °C/s and 2.90 °C/s for the alloys with 0.2wt.%Sb and 2wt.%Sb, respectively. Sb promoted an increase in the Vickers microhardness of both Sn-Ag-Sb alloys, with a higher value for the 2wt.%Sb content. In the market context, Sn-Ag-Sb alloys have high potential for application in nanotechnology, autonomous robots and artificial intelligence.

COMMITTEE MEMBERS:
Presidente - 2345599 - BISMARCK LUIZ SILVA
Externo ao Programa - 1753123 - CARLOS ALEXANDRE CAMARGO DE ABREU - UFRNExterna ao Programa - 1753896 - ZULMARA VIRGINIA DE CARVALHO - UFRNExterna à Instituição - SUYLAN LOURDES DE ARAÚJO DANTAS