Study of microstructural and mechanical anisotropy of 7075 Al deposits fabricated by cold spray additive manufacturing

In this work, microstructural and mechanical anisotropy in cold spray additively manufactured (CSAMed) 7075 Al deposits were studied in detail. For clarity, spray gun traverse direction, pass interval direction and deposition direction were defined as the X, Y and Z, respectively. Tensile tests for two different groups of samples were carried out in different orientations to study the in-plane and three-dimensional anisotropy of CSAMed 7075 Al deposits. Fracture morphology of the specimens was studied by optical microscopy (OM) and scanning electron microscopy (SEM). Transmission electron microscopy (TEM) was employed to examine particle–particle interface bonding. The results revealed that there exists a strong microstructural and mechanical anisotropy in the CSAMed deposits. The ultimate tensile strength (UTS) gradually decreased as the tensile direction changed from X/Y to Z direction. Further, crack propagation behavior was uniform in XY plane but a strong anisotropy was resulted in the planes that were perpendicular to XY plane. The underlying reason and possible mechanism related to this anisotropy was discussed in detail.