Layer-by-Layer Synthesis of Functionally Graded Amorphous-Nanocrystalline Cobalt-Based Alloy via Selective Laser Melting

Investigations layer-by-layer synthesis of amorphous-nanocrystalline material with gradient microstructure from cobalt-based powder alloy 86KGSR was carried out by using the selective laser melting technology. The factor of formation of the gradient microstructure of the material was the use of two different powder layer laser scanning strategies: linear scanning and chessboard scanning. The paper presents the results of the study of the gradient microstructure and phase composition of the compact 86KGSR alloy. The possibility of obtaining cobalt-based material with gradient microstructure via selective laser melting has been demonstrated for the first time. In general, the structure of the samples obtained is characterized by the presence of macroscopic cracks, as well as intermetallic phases precipitations in the heat affected zone. Maximum degree of amorphization of the structure estimated with image analysis turned out to be about 37% in chessboard scanning zone, when linear scanning zone demonstrated only 25%. The other major effect of changing the scanning strategy from linear to chessboard revealed itself in halving of the crack length. The results of the study can be used for further research and development of technology for obtaining amorphous-nanocrystalline soft-magnetic cobalt-based materials using selective laser melting.