Unveiling microstructure evolution and governing factors for mechanical and magnetic response in electron beam powder bed fusion processed Zr-based biomedical alloys

Zirconium (Zr)-based alloys are promising for biomedical implants due to their excellent biocompatibility, corrosion resistance and low magnetic susceptibility, critical for magnetic resonance imaging (MRI) compatibility. However, the relationship between additive manufacturing parameters, microstructure and functional properties of Zr-based alloys remains underexplored. Herein, Zr -2.5Nb alloy parts were fabricated via electron beam powder bed fusion (EB-PBF) using 40 distinct parameter sets with energy densities ranging from 25 to 230 J·mm−3. The effects of processing parameters on densification, microstructural evolution, mechanical properties and MRI compatibility were systematically investigated. Multiscale and phase-field simulations revealed the mechanisms of melt pool dynamics, thermal history and spinodal decomposition during EB-PBF. A convolutional neural network (CNN) was employed as a supplementary data-analysis approach to reveal the relative influence of coupled microstructural descriptors on magnetic susceptibility. Energy density significantly influences phase composition, microstructure and texture, dictating mechanical strength and magnetic response. Optimal parameters yielded near-full densification, a balanced tensile strength of 621.7 MPa with 23.6% elongation and a 58% reduction in MRI artefact volume compared to Ti -6Al -4V. This work provides a comprehensive framework for tailoring microstructure and multi-performance of the EB-PBF-processed Zr -2.5Nb alloys, advancing their application in the next-generation MRI-compatible implants.