Constellation, le dépôt institutionnel de l'Université du Québec à Chicoutimi

Résumé

A series of lightweight Al-based entropy alloys containing Cu, Zn, Cr, V, Ti and Fe has been designed for elevated temperature applications. The microstructure, mechanical properties at room and elevated temperatures, and the thermal stability of six entropy alloys (Al93Cu4Zn1Cr1Fe1, Al85Cu11Zn2Cr1Fe1, Al85Cu11Zn1Cr2V1, Al78Cu18Zn2Cr1Fe1, Al78Cu18Zn1Cr2Ti1, and Al78Cu18Zn1Cr2V1) were investigated. Owing to the large chemical difference and high negative enthalpy between Al and the alloying elements, the generation of a large quantity of intermetallic compounds (ICs) was inevitable. With increasing Cu content, the volume fraction of ICs increased significantly. The three high-Cu alloys (Al78Cu18Zn2Cr1Fe1, Al78Cu18Zn1Cr2Ti1, and Al78Cu18Zn1Cr2V1) exhibited high yield strengths of more than 200 MPa and excellent thermal stability at 300 °C. These values are considerably superior to those of most conventional aluminum alloys. The strengthening mechanisms at room and elevated temperatures have been discussed. The favorable thermal stability and good mechanical properties of the high-Cu alloys up to 450 °C indicate their significant potential for high temperature applications.