Characterization of defects and nanoestructural alterations in the Nimonic 80A superalloy by using Transmission Electron Microscopy

Abstract

In this work, TEM (Transmission Electron Microscope) samples of materials used in aeronautic applications were analyze. The main objective of this project was to study intercrystalline defects in Nimonic 80A superalloy after the heat treatment and fatigue testing of the samples. The samples were prepared for the TEM analysis in University of Siegen, Germany after they were test in very high cyclic loading conditions (1000 Hz y 20 000 Hz). These tests were performed because they simulate very closely the work conditions that these alloys must support in turbine and others aeronautic applications. The mechanical stresses generated in these kind of applications will develop many deformations and nanometric defects in this material. They are evidenced by the dislocations formation. The dislocations are possible to observe only by using very powerful microscopy technics such as Transmission Electron Microscope. The results obtained by the TEM analysis show that after the heat treatment, the samples developed very distinctive precipitations in the Nimonic 80A samples. Additionally, after the mechanical testing these samples shows the formation of representative kind of dislocations. Finally, this work shows the influence of the precipitations under the formations, stacking and movement of the dislocations in the microstructure of the tested samples.