Phase Formation and Texture Evolution of 316L-CuCrZr Multi-Material Structures

316L-CuCrZr Laser Powder Bed Fusion multi-material structures have attracted research interest due to their promising material combination however they pose significant issues related to cracking phenomena and hence poor structural integrity. In this study, we propose a compositional modification approach to mitigate cracking by introducing carefully selected premixture layers between 316L and CuCrZr, designed to promote ferrite formation that resists cracking. To characterize such chemically graded materials, advanced characterization methods are required. The presence of ferrite in these multi-material structures is confirmed using Polarization Contrast Neutron Analysis (PNI), while its temporal evolution is investigated via in-situ annealing Synchrotron X-ray diffraction. Neutron Bragg Edge Imaging reveals that the phase transformation from austenite to ferrite correlates with significant texture evolution and a concurrent reduction in the Coefficient of Thermal Expansion, as revealed by in-situ annealing neutron diffraction. The melt pool morphology for different premixture compositions is examined using in-situ radiographic analysis, complemented by in-situ acoustic emission monitoring. Additionally, high-speed imaging enables the estimation of temperature distribution and the solidification behavior of the various compositional steps in the multi-material structures. Post-mortem microstructure characterization, employing EBSD, TKD and STEM-EDS analysis provides a valuable tool to elucidate the mechanism of ferrite formation, while the overall mechanical behavior of the structure is evaluated using nano-indentation mapping.