Additive Manufacturing (AM) has been extensively used for 3D printing of metallic structures consisting of single alloys. In the recent years, increasing interest has been observed in Multimaterial Additive Manufacturing, as the freeform fabrication and the ability to control compositional changes within a few hundred micrometers, have constituted AM as a choice for bimetal structures fabrication [1,2]. One of the major challenges of this technique is the presence of porosity, because of either insufficient melting or gas entrapment, the latter due to the presence of a protective atmosphere (usually argon or nitrogen) during the melting-based 3D printing process. Another point of concern is the appearance of cracks due to a mismatch in physical, thermal, and elastic properties between the two printed materials, especially in the proximity of the interface, which combined with porosity and the presence of brittle intermetallic phases, can deteriorate the final mechanical performance of the structures and consequently reduce their potential technical applications.

Here we will present the high-resolution neutron tomography characterization of 316L/CuCrZr and Ni/CuCrZr composites built by different manufacturing processes. The samples comprise lattice structures of the higher melting point alloy embedded within a matrix of the second alloy with the same geometry, printed using Multimaterial Laser Powder Bed Fusion (LPBF) and a hybrid process of LPBF and Induction melting, where LPBF is used for the fabrication of lattice structures (316L or Ni) and induction casting is used for the fabrication of the matrix (CuCrZr).