Processing effects on biocompatibility and corrosion kinetics of additively manufactured Zr-based bulk metallic glass

This study assesses in vitro biocompatibility, corrosion kinetics, electrochemical passivation, and hardness of laser powder bed fusion (LPBF)-fabricated AMLOY-ZR01 (Zr59.3Cu28.8Al10.4Nb1.5 at%) bulk metallic glass (BMG) across a systematic processing matrix - laser power 33-80 W; scan speeds 75-710 mm s−1; normalized enthalpy parameter (ΔH) = 34, 44, and 54, and volumetric energy density (VED) ≈ 28-112 J mm−3. The novelty lies in integrating cyclic polarization, potentiostatic electrochemical impedance spectroscopy with equivalent-circuit modeling (R(Q(RW)) (QR)), microhardness mapping, and comprehensive Saos-2 assays (Live/Dead, Alamar Blue, scanning electron microscopy, and confocal laser scanning microscopy) to create a process-structure-bio response map for a Zr-based BMG. The methodology combined quantitative electrochemistry (Jcorr, Ecorr, ηpit, ηrp), EIS-derived film/bulk-material resistances, capacitances, and Warburg impedance, and cell metabolic/proliferation metrics to link passive-film robustness with early osteoblastic activity. Results identify an optimal normalized enthalpy ΔH = 34 and 44, VED window (≈70-90 J mm−3) that minimizes porosity (∼0.02-0.05%) and Jcorr while maximizing day-3 metabolic activity (∼26-28 a.u.). Representative outcomes include the lowest annual corrosion rate below 1 mpy, the largest pitting margin (ηpit = 424 mV), and hardness spanning ∼504-564 HV0.2. EIS parameters (R1, R2) delineate ranges of ≈0.87-827 Ω cm2 and 0.41-84.5 Ω cm2, respectively, linking film resistance to cell response. Qualitatively, LPBF AMLOY-ZR01 processed within the optimal window shows passivation and cytocompatibility comparable to or better than crystalline/as-cast references.