Abstract Over the years, the demand for high engine efficiency has resulted in the development of new generation superalloys with improved elevated temperature properties, especially creep resistance. This study aimed to evaluate creep and mechanical behavior of Inconel 718 superalloy. Creep tests were performed at temperature range of 650 to 700 °C and stress range of 625 to 814 MPa. Hot tensile and oxidation tests were performed and the characterization techniques used in this study were scanning electron microscopy (SEM) for microstructural and fracture surface analysis, transmission electron microscopy (TEM) for precipitates analysis; grazing X-ray diffraction for analysis of oxide formation and Vickers microhardness. The analyze of stress exponent value (n = 36.48) and activation energy (Qc = 512.97 kJ/mol), suggested that creep mechanism at 650 °C was the climb dislocation mechanism. The Inconel 718 presented ductile fracture at 650 and 700 °C and intergranular fracture to 675 °C.

RESUMO A aplicação de um filme de SiC/Cr em liga Ti-6Al-4V para indústria aeroespacial visa a proteção química a ação do oxigênio na liga de titânio, e aumento do tempo de vida em fluência e do tempo de fratura e a diminuição da taxa de fluência da liga a deformação plástica em relação a liga sem proteção. O objetivo deste trabalho foi investigar e avaliar a evolução microestrutural, textura e as correlações cristalinas da liga Ti-6Al-4V recoberta com filme de SiC/Cr via High Power Impulse Magnetron Sputtering (HiPIMS) antes e após os ensaios de fluência. Os ensaios de fluência foram executados em temperaturas de 500, 600 e 650 °C, na modalidade de carga constante, e nas tensões de 125, 250 e 319 MPa. As análises das amostras foram realizadas por meio de microscopia eletrônica de varredura (MEV) utilizando a técnica de difração de elétrons retroespalhados (EBSD) e espectroscopia de raios X por dispersão em energia (EDS). Os resultados na liga Ti-6Al-4V a partir de EBSD identificaram que houve mudanças microestruturais e da textura para um conjunto de direções preferencias à medida em que aumentou a tensão do ensaio de fluência, aumentou a texturização das fases Ti-α e Ti-β.

ABSTRACT The application of a SiC/Cr film in Ti-6Al-4V alloy for the aerospace industry aims to chemically protect the action of oxygen in the titanium alloy, and to increase the creep life and fracture time and reduce the creep rate of plastic deformation alloy compared to unprotected alloy. The objective of this work was to investigate and evaluate the microstructural evolution, texture and crystal correlations of the Ti-6Al-4V alloy coated with SiC/Cr film by High Power Impulse Magnetron Sputtering (HiPIMS) before and after creep tests. The creep tests performed at temperatures of 500, 600 and 650 °C, in constant load mode stresses of 125, 250 and 319 MPa. The analyses of the samples were carried out by means of scanning electron microscopy (SEM) using the technique of backscattered electron diffraction (EBSD) and energy dispersion X-ray spectroscopy (EDS). The EBSD results on Ti-6Al-4V alloy were identified that there were microstructural changes and texture for a set of preferred orientations that with increased the creep test load stresses, the Ti-α and Ti-β phases texturization increases.

AbstractIn this paper, chrome (Cr) thin films were deposited and used as interlayer between SiC films and Ti-6Al-4V substrates. Films and interlayers were obtained by using HiPIMS (High Power Impulse Magnetron Sputtering) technique. Interlayers were growth for 5, 30, and 60 minutes. The films were analyzed with respect to morphology, stoichiometry, thickness, roughness, and adhesion. The results showed that the HiPIMS technique was efficient to produce dense thin films and that the adhesion increased with Cr thickness.