Laser powder-bed fusion (LPBF) of multi-material components is a rapidly growing field with a range of potential applications. To realize this potential, a comprehensive understanding of the phase evolution during the process, especially at the interfaces, is necessary. Processability of a given alloy combination highly depends on understanding the solidification and phase transformation routes and their manipulation using the process parameters during LPBF. This study investigates the phase evolution during multi-material laser powder-bed fusion of 316L and 17-4 PH stainless steels, Inconel 625 nickel-based superalloy, and CuCrZr copper alloy, with a focus on the interfacial regions. The materials were printed in different combinations and configurations and operando synchrotron X-ray diffraction measurements were conducted. X-ray diffraction patterns were collected over successive layers around the interfaces during melting and solidification. A single phase FCC structure has been observed at the Inconel 625/316L interface whereas an FCC-BCC mixture has been observed at the Inconel 625/17-4 PH interface as expected.  On the other hand, while the alloying elements did not produce any detrimental intermetallics, phase separation and formation of a new matrix phase have been observed at the CuCrZr/316L, CuCrZr/17-4PH and CuCrZr/Inconel 625 interfaces upon solidification. These results provide a deeper understanding of the solidification behavior of multi-material combinations involving these alloys during laser powder-bed fusion and hold promise for the improvement and optimization of multi-material components in future applications.