Study of the elaboration of high entropy material from powder by laser additive manufacturing

Abstract If Stellite® 6 is a cobalt base alloy with a hard coating well known for its good wear resistance, its use is not desirable for nuclear installations due to the activation of cobalt under neutron flux which makes maintenances more delicate as, later, decommissioning. If several studies have led to propose certain hard coatings without cobalt, for the moment, none equals the wear properties of Stellite® 6. The present research aims to explore the recent research area on high entropy alloys or concentrated composition alloys (HEA/CCA) as a new path for the development of innovative hard coatings. The study is based on the use of thermodynamics simulations with CALPHAD in order to predict the compositions of a large number of alloys, after an initial selection of the acceptable elements (NiFeCrMoTi in this study). Then, Laser Metal Deposition (LMD) is used for manufacture walls of graded compositions for a rapid screening of compositions and coatings for later wear tests. The metallurgical analyses of the elaborated samples allow selecting the most promising ones on which wear pin-on-disk tests are finally conducted. The wear tests have evidenced promising behavior for the selected HEA/CCAs.