Selective laser melting of CoCrFeNiMn high entropy alloy powder modified with nano-TiN particles for additive manufacturing and strength enhancement: Process, particle behavior and effects

Selective Laser Melting (SLM) was applied for Additive Manufacturing (AM) of CoCrFeNiMn high entropy alloy (HEA) and TiNp/CoCrFeNiMn composite, with the tailored laser parameters for as-printed bulk densification after the process optimization. The pre-alloyed HEA powder by gas-atomization was modified with nano-TiN ceramic particles on the powder surface layer and employed to fabricate HEA matrix composite with uniformly dispersed TiN reinforcements via SLM. The hierarchical microstructures with strong crystallographic textures were generated in the as-printed HEA parts. While in the TiNp/HEA composite, the remarkably refined and nearly equiaxial HEA matrix grains were produced due to the contribution of introduced TiN particles. The average ultimate tensile strength (sigma(UTS)) of as-printed composite achieved 1036 MPa with the average elongation to fracture (e(f)) as similar to 12%. By contrast, the average sigma(UTS) and e(f) of as-printed HEA were 601 MPa and similar to 30% respectively. The strengthening mechanism of the SLM-fabricated TiNp/HEA composite was further elucidated. (C) 2019 Elsevier B.V. All rights reserved.