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The additive manufacturing (AM) of nitinol (NiTi) has gained considerable attention due to the capability of this material and processing combination to produce complex structures with desired shape memory or superelastic properties. Finite element analysis models were developed in this work to simulate the load-bearing capability of Laser Powder Bed Fusion (PBF-LB) produced NiTi lattice structures. The Auricchio numerical method, with exponential hardening law, was implemented within the FEA model to take account of the martensite-austenite reorientation upon change of stress state. The strut diameter and the unit cell side length were varied which in turn varied the lattice relative density. The lattice structures were subjected to 7 % compressive strain under isothermal conditions. The highest energy absorption efficiency of 40 % was achieved from the lattice structure with a strut diameter of 2 mm, a 6 mm unit cell side length, and a relative density of 42 %; however, the highest specific peak stress was recorded within the lattice structure having a strut diameter of 2.5 mm, a 4 mm unit cell side length, and a relative density of 62 %. Transient analysis was performed by varying the compression rate from 0.25 mm/s to 1 mm/s. For all loading conditions, the energy absorption increased linearly until a stable stress plateau was reached. Moreover, for these examined compression rates, the maximum stress absorption efficiencies varied within the range of 25 %–33 %.

The present study reports the glass-forming ability, density change on crystallization and corrosion behavior of newly developed rare-earth free Cu-based metallic glasses (CBMGs). The critical casting thickness of these new CBMGs increased from 15 mm at 8 at.% Hf to 22 mm at 12 at.% Hf, reaching a maximum value of 28.5 mm at 13.5 at.% Hf. It dropped to 24 mm and 15 mm thereafter, for 15 and 20 at.% Hf, respectively. The alloys showed a monotonic increase in density going from 8 at.% Hf to 20 at.% Hf, with the density of amorphous samples increasing from 7.83 g/cm3 to 8.84 g/cm3 and crystallized samples increasing from 7.92 g/cm3 to 8.91 g/cm3. Potentiodynamic polarization tests carried out in 0.1, 0.2 and 0.5 M NaCl solution at 25 °C showed a direct correlation between corrosion resistance and Hf content in the order: 8 at.% < 13.5 at.% < 20 at.% Hf. Increase in NaCl concentration also had a significant impact on the corrosion intensity due to the chaotropic effect. Scanning electron microscopy of corroded sample surfaces showed formation and eventual merging of individual micro cracks resulting in a mud-cracking pattern. Energy-dispersive X-ray spectroscopy maps of pitted regions revealed reduction in Zr and Al concentration with increase in Hf and Cu percentage for all compositions. An increase in the O concentration along with the appearance of new peaks in the X-ray photoelectron spectroscopy results, measured post corrosion, confirmed the formation of metal oxides and oxyhydroxides in the passive layer.