Evolução estrutural e estabilidade térmica do sistema Ni-Ti-Si submetido a moagem de alta energia

Abstract

This research shows the obtained results from the high energy mechanical milling of Ni, Ti and Si powders using different combinations of experimental conditions, which included the use of planetary and vibratory type mills, as well as the use o inert and emnviroment atmosphere. The structural evolution of the samples was monitored using the X-ray diffraction (XRD) technique, where all the diffractograms were quantified using the Rietveld method and the thermal stability of the samples analyzed by Exploratory Differential Calorimetry (DSC). It was possible to verify the nucleation of the ternary phase NiTiSi of orthorommbic structure, and the Ti5Si3 intermetallic compound of hexagonal structure, in all the diffractograms analyzed, regardless of the type of mill used or the atmosphere of grinding. In the sample synthesized in Vibratory mill, under inert atmosphere, at the end of 32h of grinding, it was still possible to distinguish a small portion of the elemental phase of Nickel. In the samples ground through a planetary mill, the nucleation of the high temperature austenitic phase NiTi, of cubic structure, was identified. By differential scanning calorimetry, it was found that the nanostructured samples are reasonably stable up to at least 600 oC.