Bonding Analysis of Cold Sprayed Single Particle High Entropy CrMnCoFeNi Alloy
Wednesday, May 26, 2021: 9:30 AM
Dr. Roghayeh Nikbakht
,
University of Ottawa, Ottawa, ON, Canada
Dr. Mohammad Saadati
,
École de Technologie Supérieure (ETS), Montreal, QC, Canada
Prof. Taek-Soo Kim
,
Korea Institute for Rare Metal, Korea Institute of Industrial Technology (KITECH), Goryeong-gun, ON, Korea, Republic of (South)
Prof. Mohammad Jahazi
,
ETS, Montreal, QC, Canada
Prof. Hyoung Seop Kim
,
Pohang University of Science and Technology (POSTECH), Pohang, Korea, Republic of (South)
Prof. Bertrand Jodoin
,
University of Ottawa (uOttawa), Ottawa, ON, Canada
The equiatomic CrMnCoFeNi high entropy alloy (HEA) represents an excellent combination of strength and ductility. These properties stem from its unique microstructural characteristics such as deformation twinning which is responsible for its excellent strain hardening rate. The transition from dislocation glide to deformation twinning requires sub-zero temperatures and/or high stresses to be activated. Therefore, cold spray (CS) consolidation, involving high strain rates, cold and severe plastic deformation is a method that can activate these mechanisms.
In this study, CS of single particles is conducted to explore macrostructure/microstructure deformation evolution of the HEA and its bonding characteristics on Ni, stainless steel and Inconel 625 substrates.
Particles in HEA/Inconel and HEA/Ni pairs show the highest flattening and penetration depth with the HEA/stainless steel and HEA/HEA being in between. EBSD and ECCI analyses of particles’ cross-sections show that particles for all severally deformed and dynamically recrystallized areas extend from sheared zones to the center and top of particles. Deformation nano-twins are formed in HEA particles with thickness of about 200 nm. HEA/HEA impacts have the highest critical velocity and the lowest quality of bonding. This is attributed to the excellent strain hardening of this alloy which potentially postpones shear localization and impedes bonding.
