Mechanical, electrochemical and permeability behaviour of Ti6Al–4V scaffolds fabricated by electron beam powder bed fusion for orthopedic implant applications: The role of cell type and cell size

Abstract

Ti–6Al–4V scaffolds have attracted much attention for biomedical applications owing to their bone-mimicking mechanical properties and better bone tissue in-growth and additive manufacturing can be employed to fabricate complex geometry scaffolds. The present study aimed to investigate the effects of scaffold architecture on the mechanical, electrochemical, and permeability behaviour of Ti–6Al–4V scaffolds fabricated by electron beam powder bed fusion (EB-PBF). For this, scaffolds with diamond and rhombic dodecahedron cell types, having various cell sizes, were designed and successfully fabricated. Chemical etching minimized the surface defects and improved the geometric fidelity of the scaffolds compared to the original designs. The larger the cell size, the coarser the dual α/β phase microstructure due to the higher heat accumulation in thicker struts. The scaffold architecture proved significant effects on the mechanical properties, where all scaffolds were mechanically comparable with human bone. Short/long-term electrochemical corrosion tests indicated that the corrosion performance significantly improved with an increase in cell size, irrespective of the cell type; this was attributed to the lower exposure of surface area to the electrolyte, coarse microstructure and a higher fraction of β phase. This study recommended that the EB-PBF Ti–6Al–4V scaffolds are promising candidates for orthopaedic implant applications from mechanical and electrochemical points of view.