Crack-free Laser Additive Manufacturing

LAM is a transformative technology enabling layer-by-layer fabrication of complex components. However, when this process is applied to nickel-base superalloys components, the mechanical integrity is plagued by hot-cracking. These detrimental features originate in the chemical composition imbalance at the solid-liquid interface causing the liquid and solid phases to coexist over a wide temperature range during solidification. This is further exacerbated by the volumetric shrinkage and intergranular stresses introduced by the fast-moving laser. Discovering the mechanism for hot-cracking remains challenging due to the transient nature of the process and the resulting micro- to nanoscale microstructure. Here, we will develop a correlative materials characterisation route combining 3D nano-computed tomography (with 10 nm resolution), Electron Backscatter Diffraction and Dark Field X-ray Microscopy to establish the conditions that trigger crack initiation from a LAM process.