Fig. 1. BSE images showing (a) the spherical morphology and (b) surface of the prealloyed powders, (c) cross section of micrometer-sized dendrites with random orientations (d) and (e) particle size distribution measured by using a laser granulometry and the average size is calculated to be 50.7 μm.

Fig. 2. BSE images showing (a) the melt pools and (b) columnar dendrites on the XZ plane. In both images (a, b), the melt pool boundaries were indicated by white arrows. BSE images revealing (c) the laser scanning traces with a rotation angle of 67° and (d) honeycomb-like domains (cell structure) on the XY plane. The insert in (d) is a high magnification BSE image. (e) SEM image exhibiting the inter- and intragranular precipitates in PM alloy. The insert image in (e) is a BSE image showing the carbides located on the grain boundaries. (f) High magnification image for intragranular γ’ phase.

Fig. 3. BSE image revealing the influence of melt pool boundaries on the growth of dendrites.

Fig. 4. EBSD IPF maps (a-c), grain boundary maps (d-f) and KAM maps (g-i) for the SLM and PM alloys. (a, d, g) are observed from the XY plane while (b, e, h) are from XZ plane of the SLM alloy. (c, f, i) Corresponding images of the PM alloy.

Fig. 5. Pole figures for (a) SLM alloy and (b) PM alloy. Note that the pole figure corresponding to SLM alloy is obtained from the XY plane.

Fig. 6. (a) BSE image showing a solidification crack, (b) overlapped image with IPF and band contrast maps, (c) relative to the first point misorientation marked as line 1 and line 2 and (d) solidification cracks originate from closed or semi-opened shrinkage cavities, the insert showing the occurrence of crack healing.

Fig. 7. (a) BSE image showing a typical liquation crack and (b) composition corresponding to liquid film within the clack and γ matrix, respectively.

Fig. 8. Thermodynamic calculations for the solidification path based on the equilibrium and non-equilibrium (Scheil model) condition.

Fig. 9. (a, b) Bonding defects and (c) pore in SLM alloy.

Fig. 10. Microstructures in SLM and PM alloys after heat treatment: (a, b) the γ’ precipitates for SLM and PM alloys; (c, d) EBSD IPF maps obtained on the XY and XZ planes in SLM alloy; (e) EBSD IPF map for PM counterpart.

Fig. 11. Recrystallization maps prior to heat treatment: XY plane for (a) SLM alloy and (b) PM alloy; (c) corresponding fraction distribution of recrystallized, substructured and deformed microstructures for SLM and PM alloys.