Banca de DEFESA: CAMILA BOLDRINI NASCIMENTO

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : CAMILA BOLDRINI NASCIMENTO
DATE: 16/06/2023
TIME: 14:00
LOCAL: https://conferenciaweb.rnp.br/sala/renato-29
TITLE:

Characterization of the corrosion behavior of CoCrFeNi and CoCrFeNiAl high entropy alloys

PAGES: 102
BIG AREA: Engenharias
AREA: Engenharia de Materiais e Metalúrgica
SUBÁREA: Metalurgia Física
SPECIALTY: Corrosão
SUMMARY:

    In this work, CoCrFeNi and CoCrFeNiAl high entropy alloys were obtained by arc furnace melting under an argon atmosphere. The objective was to investigate the interplay between alloy microstructure, composition of the surface oxide film, electronic properties of the passive film and the corrosion behavior in 3.5 wt.% NaCl solution at room temperature. The crystalline structure of the alloys was analyzed by X-ray diffractometry. The microstructure was examined by optical microscopy and scanning electron microscopy. The surface chemical states were assessed by X-ray photoelectron spectroscopy (XPS). The corrosion behavior was evaluated by electrochemical impedance spectroscopy and potentiodynamic polarization. The samples remained immersed in the electrolyte for up to 28 days. The electronic properties of the passive film will be determined in the next steps of the project, based on Mott-Schottky plots. The results obtained so far indicate that the CoCrFeNi alloy is comprised of one single face centered cubic (FCC) crystalline phase. Aluminum addition promoted the formation of a mixed structure, comprised of two crystalline phases, one body centered cubic (BCC) and one ordered BCC phase (B2). The passive film is comprised of a complex mixture of oxides and hydroxides (chromium, iron, nickel, cobalt, and, for the CoCrFeNiAl alloy, also aluminum). The major components of the CoCrFeNi alloy surface oxide film are Cr₂O₃ and Cr(OH)₃. Aluminum addition modified the composition of the passive film, leading to a predominance of Al₂O₃ and Al(OH)₃ for the CoCrFeNiAl alloy. Pitting corrosion susceptibility was dependent on the chemical composition of the high entropy alloy. Aluminum promoted the formation of a thicker oxide film. However, it decreased the corrosion resistance with respect to the CoCrFeNi alloy.

COMMITTEE MEMBERS:
Presidente - Interno ao Programa - 1671298 - RENATO ALTOBELLI ANTUNES
Membro Titular - Examinador(a) Interno ao Programa - 1282172 - ROBERTO GOMES DE AGUIAR VEIGA
Membro Titular - Examinador(a) Externo ao Programa - 2297395 - FREDERICO AUGUSTO PIRES FERNANDES
Membro Titular - Examinador(a) Externo ao Programa - 1925199 - ANIBAL DE ANDRADE MENDES FILHO
Membro Titular - Examinador(a) Externo à Instituição - JEAN VICENTE FERRARI - USP
Membro Suplente - Examinador(a) Interno ao Programa - 1671394 - HUMBERTO NAOYUKI YOSHIMURA
Membro Suplente - Examinador(a) Interno ao Programa - 1961116 - DEMETRIO JACKSON DOS SANTOS
Membro Suplente - Examinador(a) Interno ao Programa - 1545738 - MARCIA TSUYAMA ESCOTE
Membro Suplente - Examinador(a) Externo ao Programa - 2604737 - EVERALDO CARLOS VENANCIO
Membro Suplente - Examinador(a) Externo à Instituição - RICARDO ALEXANDRE GALDINO DA SILVA - UNIFESP