Sacrificial templating offers the ability to create interconnected pores within 3D printed filaments and to control pore morphology. Beta-tricalcium phosphate (TCP) bone tissue engineering (BTE) scaffolds were fabricated with multiscale porosity: (i) macropores from direct ink writing (DIW, a material extrusion 3D printing technique), (ii) micropores from oil templating, and (iii) smaller micropores from partial sintering. The hierarchically porous scaffolds possessed a total porosity of 58-70 %, comprising 54-63 % interconnected open pores. The in vitro results demonstrated that scaffolds with macroporosity promoted human osteoblast growth more than scaffolds with only microporosity. The elongated pores from the capillary suspension filament microstructure induced greater cell spreading than the sphere-like pores from the emulsion. Overall, the hierarchically porous scaffold with capillary suspension TCP filaments provided a superior microenvironment for significantly higher cell viability and proliferation than the other scaffolds, including a poly(ε-caprolactone) (PCL) control, a material currently used clinically as porous BTE scaffolds. The cellular response was further enhanced when macropore size was in the range of 570-590 μm. Therefore, the hierarchically porous scaffolds in this study are promising as BTE scaffolds, and the reported process of DIW of oil-templated colloidal pastes is a feasible strategy with potential for further customization.

This paper presents the results of a preliminary investigation into the corrosion resistance of laser powder bed fusion (LPBF)‐produced Scalmalloy® specimens built by Boeing Space, Intelligence, and Weapons Systems (BSI&WS). The specimens were first exposed to a 5% NaCl salt fog test at 35°C, and a comparison was made with prior tests on the aluminum alloy AA7050‐T7451. The AA7050‐T7451 alloy was chosen since it is widely used in fixed‐wing aircraft, rotary‐wing aircraft, and in space structures. This preliminary study reveals that BSI&WS LPBF‐built Scalmalloy® is significantly more resistant to corrosion pitting than AA7050‐T7451. These prior exposed (Scalmalloy®) specimens were then fatigued tested, and it was shown that exposure for 28 days to a 5% salt spray fog environment at 35°C did not reduce the durability of the specimens. As such, this study, when taken in conjunction with the authors' previous report on the exceptional damage tolerance of Scalmalloy®, reveals that the BIS&WS LPBF Scalmalloy® is particularly attractive for use on a range of both fixed‐ and rotary‐wing military aircraft. It also reinforces the potential for BSI&WS LPBF Scalmalloy® to be used in building parts for attritable aircraft/drones.