Issue 50

V. Kytopoulos et alii, Frattura ed Integrità Strutturale, 50 (2019) 414-422; DOI: 10.3221/IGF-ESIS.50.35 414 Focused on the research activities of the Greek Society of Experimental Mechanics of Materials A SEM-X-Ray assisted experimental approach for the determination of mechanical and thermal load – induced damage in MMCs Victor N. Kytopoulos, Emilios Sideridis, John Venetis, Chrysoula Riga Department of Mechanics, National Technical University of Athens, 5 Heroes of Polytechnion Avenue, Athens, Greece victor@central.ntua.gr Alexandros Altzoumailis School of Chemical Engineering, National Technical University of Athens, 5 Heroes of Polytechnion Avenue, Athens, Greece ajumaily@central.ntua.gr A BSTRACT . An experimental technique is presented to evaluate mechanical and thermal load-induced microstructural damage, based on the Electron Probe Micro-Analysis (EPMA) principle, by which certain analytical potentialities of Scanning Electron Microscopy (SEM) are used. The aim of the study is to apply this technique in the case of metal matrix composites (MMCs). Based on earlier findings it is shown that by this technique the damage-controlled micro- structural integrity distribution ahead of an edge-notch under tension is deter- mined with sufficient reliability. To demonstrate this fact two MMCs were tested. Dog-bone specimens with an edge notch were subjected to slow tension up to their ultimate stress, the loading process was terminated and the EPMA technique was applied. The procedure was also applied after sudden cooling of the specimens by immersion in liquid hydrogen. It is shown that the MMC with larger differences between the elastic and plastic constants of the inclusion and the matrix exhibit increased proneness to mechanical and thermal load-induced damage. The findings obtained are discussed on the basis of the dominating combined influence of macro-microscopic mechanical and thermo-elastic stress concentration processes on the matrix-particle interfacial fracture strength. K EYWORDS . (Micro)-damage; X rays; MMCs; Thermal shock-stress; Process zone; Microstructural integrity. Citation: Kytopoulos, V.N., Sideridis, E. Venetis, J., Riga, Ch.., Altzoumailis, A., A SEM- X-Ray assisted experimental approach for the determination of mechanical and thermal load - induced damage in metal matrix composites, Frattura ed Integrità Strutturale, 50 (2019) 414- 422. Received: 24.01.2019 Accepted: 28.05.2019 Published: 01.10.2019 Copyright: © 2019 This is an open access article under the terms of the CC-BY 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. I NTRODUCTION odern materials such as aluminum-alloy-based Metal Matrix Composites are the new candidates for a variety of engineering applications. Aluminum and its alloys have been used as the main constituent due to their wide application in advanced structural, automotive, aviation, aerospace, marine and defense sectors. The mechan- M