Fig. 4: The effect of solute trapping on the solidification behaviours and crack susceptibility.

a Distribution of γ′ forming elements in the heat-affected zone (HAZ). b Composition deviation of γ′ forming elements (Al, Ta, and Ti) from the nominal one (the plane of composition deviation = 0) in the HAZ. c Schematic diagram of the characteristics of microstructure and segregation pattern. d Comparison of the freezing range (FR) and segregation range (SR) in the phase diagrams under equilibrium and rapid solidification conditions. The outer area depicts the equilibrium solidification process, and the inner one stands for the quasi-solute trapping effect under the rapid solidification condition. The projection on the vertical axis is the freezing range, and the one on the horizontal axis is the segregation range. ml and ms are slopes of liquidus and solidus, respectively. Subscript e and v indicate the equilibrium state and the rapid solidification condition, respectively. e–g Suppression of the crack propagation by the solute trapping observed in the AM of CM247LC⁴⁷ (e), Hastelloy X¹⁸ (f) and Inconel 738LC⁴⁸ (g). *Fig. 4e is adapted from Ghoussoub, J.N., Tang, Y.T., Dick-Cleland, W.J.B. et al. On the Influence of Alloy Composition on the Additive Manufacturability of Ni-Based Superalloys. Metall. Mater. Trans. A 53, 962-983, Copyright Springer Nature (2022). https://doi.org/10.1007/s11661-021-06568-z. Figure 4f is adapted from Harrison, N. J., Todd, I. & Mumtaz, K. Reduction of micro-cracking in nickel superalloys processed by Selective Laser Melting: A fundamental alloy design approach. Acta Mater. 94, 59–68, Copyright Elsevier (2015). https://doi.org/10.1016/j.actamat.2015.04.035. Figure 4g is adapted from Vilanova, M., Taboada, M.C., Martinez-Amesti, A., Niklas, A., San Sebastian, M., Guraya, T. Influence of Minor Alloying Element Additions on the Crack Susceptibility of a Nickel Based Superalloy Manufactured by LPBF. Materials, 14, 5702, Copyright MDPI (2021). https://doi.org/10.3390/ma14195702.