Bulk fracture anisotropy in Cold-Sprayed Al 6061 deposits

Tensile and fracture anisotropy were studied in helium-sprayed bulk Al 6061 cold spray deposits. Tensile properties (elastic modulus, yield strength, tensile strength, and elongation at break) were measured in the two in-plane principal deposit directions (long-rastering, and stepping), and fracture toughness was characterized for six principal load/crack direction pairs defined with respect to the spray directions. No in-plane anisotropy was measured for the tensile properties, attributed to uniform in-plane microstructure. Fracture toughness was found to be mildly transversely isotropic, with equal values when crack propagation was in-plane (mean of 11.0 MPa root m) and slightly higher values when crack propagation was out-of-plane (through the deposit thickness, mean of 13.0 MPa root m). The overall fracture toughness range was 40-50% that of wrought Al 6061-T6. In-plane fracture was almost completely interparticular (fracture along particle interfaces), while out-of-plane fracture was a mixture of interparticular and trans particular (fracture through particles). A greater amount of transparticular fracture was observed in orientations with higher toughness. Overall, the low level of anisotropy was attributed to good interparticle bonding as a result of effective spray parameters and the use of helium as the accelerating gas.

Automated summary

This study investigated the tensile and fracture anisotropy in helium-sprayed bulk Al 6061 cold spray deposits. The results showed no in-plane anisotropy in tensile properties, while the fracture toughness exhibited mild transverse isotropy. The low level of anisotropy was attributed to effective spray parameters and the usage of helium gas, ensuring good interparticle bonding.