Microstructural evaluation of Ti-6Al-4V with widmanstatten structure and thermal barrier coating

The affinity of titanium alloys by oxygen is one of the main factors that limit their application as structural material at high temperatures. Coatings become important due to the needs to develop materials that can be used in more aggressive conditions. The aim of this work is to evaluate the microstructure after creep test of Ti-6Al-4V with Widmanstatten structure with thermal barrier coating (CoNiCrAlY + ZrO(2)), applied by thermal spray. Creep tests were performed at 600 degree C, and stress conditions of 125, 250 and 319 MPa at constant load. After creep test the material was analyzed by optical microscopy and scanning electron microscopy. The micro structural analysis shows that the material had ductile fracture characterized by the formation and coalescence of microcavities with different shape and sizes. The quantity and form of the microcavities are influenced by stress applied during creep tests.