Journal: Nature Communications

Article Title: 3D ink-extrusion additive manufacturing of CoCrFeNi high-entropy alloy micro-lattices

doi: 10.1038/s41467-019-08763-4

Figure Lengend Snippet: Creating CoCrFeNi high-entropy alloys via 3D ink-extrusion, reduction and sintering of oxide powder blends. a TGA mass loss of a loose blend of Co 3 O 4 + Cr 2 O 3 + Fe 2 O 3 + NiO as function of temperature in a H 2 atmosphere. Initial reduction of Co 3 O 4 , Fe 2 O 3 and NiO (blue shading) is followed by reduction of Cr 2 O 3 (green shading). Inset: Same data as function of time, showing ramp and 1 h hold at 1557 K, when continuous mass loss occurs due to ongoing reduction of Cr 2 O 3 until it is fully consumed. b Scanning electron micrograph of the blended oxide powder prior to TGA, showing agglomerate sizes <10 μm and sub-micron particle size. Scale bars are 5 µm and 1 µm (inset). c Combined 2D diffractograms of blended oxide prior (left) and after (right) the TGA measurement in H 2 showing the complete disappearance of all oxide-related diffraction intensities and formation of a face-centered cubic CoCrFeNi HEA. Scale bar is 20 nm –1 . d The two-step processing route first shapes the mill-mixed ink using 3D ink-extrusion into the desired architecture (a micro-lattice with 200 µm diameter struts, in the present example). In a second step, the powders in the green body are co-reduced, inter-diffused and sintered to yield a CoCrFeNi HEA micro-lattice with much smaller overall dimensions and strut diameter, without warping or cracking. Scale bars are 3 mm

Article Snippet: 2D X-ray diffraction on milled Co 3 O 4 + Cr 2 O 3 + Fe 2 O 3 + NiO feedstock powder prior and after TGA is performed on a Bruker KAPPA APEX II with a Mo source.

Techniques:

Journal: Nature Communications

Article Title: 3D ink-extrusion additive manufacturing of CoCrFeNi high-entropy alloy micro-lattices

doi: 10.1038/s41467-019-08763-4

Figure Lengend Snippet: Phase evolution upon co-reduction of 3D printed blended oxides by in-situ synchrotron XRD in H 2 . a XRD diffractograms of a 250 µm diameter filament extruded from blended Co 3 O 4 + Cr 2 O 3 + Fe 2 O 3 + NiO inks (bottom) and the inter-diffused fcc HEA filament after completion of the co-reduction step (top). Inset: full data range of the fcc HEA alloy. b Evolution of the integrated peak intensities for Co 3 O 4 , Cr 2 O 3 , Fe 2 O 3 , and NiO, demonstrating sequential reduction forming Co, Ni, Fe between 573 and 637 K, followed by reduction of Cr 2 O 3 between 1073 and 1215 K. c 2D phase evolution plot (temperature vs. the scattering vector q, with diffraction peak intensity as color map) during in situ XRD upon heating and reduction in H 2 , illustrating the complex pathway to CoCrFeNi HEA alloy formation

Article Snippet: 2D X-ray diffraction on milled Co 3 O 4 + Cr 2 O 3 + Fe 2 O 3 + NiO feedstock powder prior and after TGA is performed on a Bruker KAPPA APEX II with a Mo source.

Techniques: In Situ, Plasmid Preparation