Unveiling the effect of ECAP on the passive film stability, surface chemistry and corrosion resistance of the β-type Ti-29Nb-13Ta-4Mo alloy

Autor(es)

Ribeiro, Alexandre Neves ; da Silva, Luis Marcelo Garcia ; Filho, Anibal de Andrade Mendes ; Antunes, Renato Altobelli ; Santos, Sydney Ferreira

• Tipo de documento: Artigo Científico
• Fonte: Applied Surface Science; v. 706, p. 16-pg., 2025-10-15.

Resumo

This study investigates the effect of equal channel angular pressing (ECAP) on the passive film stability, surface chemistry, and corrosion resistance of the beta-type Ti-29Nb-13Ta-4Mo (TNTM) alloy. Up to eight ECAP passes was performed at 350 degrees C in a 120 degrees die. The microstructural evolution was analyzed using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The surface chemical composition was assessed by X-ray photoelectron spectroscopy (XPS), while the corrosion behavior was evaluated through electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization tests in phosphate-buffered saline (PBS). The electronic properties of the passive films were examined using the Mott-Schottky approach. The as-received TNTM alloy exhibited an equiaxed beta-phase grain structure, which became elongated after two ECAP passes. After four passes, grain boundaries were no longer discernible, and after six passes, the most refined microstructure was observed, accompanied by the formation of a metastable alpha'' phase. The passive films of both as-received and ECAPprocessed samples primarily consisted of Ti, Nb, Ta, and Mo oxides. However, after six passes, the oxide layer was entirely composed of Ti oxides, predominantly TiO2. Corrosion resistance was significantly influenced by the number of ECAP passes, reaching its highest level after six passes. The study discusses the corrosion mechanisms in relation to the microstructural evolution and deformation induced phase transformations, passive film composition, and semiconducting properties of the oxide layers, highlighting the role of ECAP in enhancing the electrochemical stability of TNTM alloys. (AU)

• Processo FAPESP: 19/22183-6 - Electrocatálise VI: aspectos fundamentais e aplicados em problemas emergentes e clássicos em conversão eletroquímica de energia
• Beneficiário: Edson Antonio Ticianelli
• Modalidade de apoio: Auxílio à Pesquisa - Temático