Adaption of metal injection molding to quinary high entropy alloys A. Grimonprez 1, Y. Chen 1, A. Kauffmann 1, V. Piotter 1, J. Wagner 2, M. Heilmaier 1 1 Karlsruhe Institute of Technology, 2 University of Stuttgart KIT- Institute for Applied Materials 1 cm KIT - University of the State of Baden-Wuerttemberg and National Research Center of the Helmholtz Association www.kit.edu
Motivation Is it possible to produce High Entropy Alloy parts with Powder Injection Molding? Casting of HEA leads to heterogeneities (e.g. microstructure) Obtain parts with high homogeneity & density thus good mechanical properties Compare with: Casting methods Other PM processes 2 28.02.2017 A. Grimonprez - Adaption of metal injection molding to quinary high entropy alloys
High-entropy alloys (HEA) High configurational entropy Lattice distorsion Sluggish diffusion Cocktail effect possibility of new exceptional properties CoCrFeMnNi 1 Single phase with fcc crystal structure High strength & ductility Application as structural material 1 Cantor et al., Mater. Sci. Eng., A 375 (2004) 2 Wang et al., MDPI, Entropy 15 (2013) CoCrFeMnNi 2 3 28.02.2017 A. Grimonprez - Adaption of metal injection molding to quinary high entropy alloys
Powder injection molding (PIM) Big volume of parts & short time = cost-efficient Complex geometry & near-net shape = reliable Less waste & energy consumption = environmentally friendly PIM process 1 1 European Powder Metallurgy Association (2013) 4 28.02.2017 A. Grimonprez - Adaption of metal injection molding to quinary high entropy alloys
Content Arc melting Gas atomization PIM Mechanical testing 5 28.02.2017 A. Grimonprez - Adaption of metal injection molding to quinary high entropy alloys
Arc melting 8 buttons produced Each button remelted and flipped 5 times for homogeneity and drop cast as a rod Need to compensate for Mn evaporation to get the nominal composition (20 at% of each element) Arc melter AM/0.5 1 At% Co Cr Fe Mn Ni ICP-OES 2 20.4 19.7 20.3 19.2 20.4 1 Edmund Bühler GmbH 2 Courtesy of Dr. T. Bergfeldt, KIT 6 28.02.2017 A. Grimonprez - Adaption of metal injection molding to quinary high entropy alloys
Gas atomization Gas atomization principle 1 1 Courtesy of PW Technology CoCrFeMnNi rods in a crucible of a vacuum induction furnace 7 28.02.2017 A. Grimonprez - Adaption of metal injection molding to quinary high entropy alloys
Gas atomization Particle size distribution of the big receiver CoCrFeMnNi powder 12 10 8 Vol in % 6 4 2 0 1 10 100 1000 10000 diameter in µm 118 µm ( ~ 90 vol%) Sieving < 80, <50, <32 µm 500 µm 8 28.02.2017 A. Grimonprez - Adaption of metal injection molding to quinary high entropy alloys
Gas atomization CoCrFeMnNi powder Single fcc phase Spherical particles 20 µm Dendritic microstructure 9 28.02.2017 A. Grimonprez - Adaption of metal injection molding to quinary high entropy alloys
Feedstock development CoCrFeMnNi metal powder: 50 < x < 80 µm Composition of feedstock (vol%) 24 1 Trials with different amounts of metal powder 63 vol% 50 vol% 25 Metal Wax 50 PE Stearic acid 10 28.02.2017 A. Grimonprez - Adaption of metal injection molding to quinary high entropy alloys
Debinding and sintering 1 cm 1 cm 1400 1200 Temperature in C 1000 800 600 400 200 1 2 sintering debinding 50 vol% metal powder Cycle 1 Cycle 2 0 0 5 10 15 20 25 Time in h 11 28.02.2017 A. Grimonprez - Adaption of metal injection molding to quinary high entropy alloys
Microstructure of PIM sample Close porosity 5% Open porosity > 30% 50 µm 12 28.02.2017 A. Grimonprez - Adaption of metal injection molding to quinary high entropy alloys
Mechanical tests PIM MA 1 Cast 2 10 µm Hardness (HV) Standard deviation (HV) Load (g) 140 145 160 20 3 15 10 50 10 No cracks observed Ductile deformation 1 Irving et al., JOM vol 35, No 12 (2013) 2 Schuh et al., Acta Mater. 96 (2015) 13 28.02.2017 A. Grimonprez - Adaption of metal injection molding to quinary high entropy alloys
Conclusion It is possible to produce parts made out of HEA with PIM Powder particles have good homogeneity Residual porosity by PIM Low hardness & ductile behavior 14 28.02.2017 A. Grimonprez - Adaption of metal injection molding to quinary high entropy alloys
Outlooks Gas atomization Increase the yield of small particles by adjusting the parameters (e.g. atmosphere) Feedstock production Find the right ratio metal/binder Find an appropriate debinding procedure Mechanical tests Tensile and compression tests (room and high T) 15 28.02.2017 A. Grimonprez - Adaption of metal injection molding to quinary high entropy alloys
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