Harmonic heterostructured pure Ti fabricated by laser powder bed fusion for excellent wear resistance via strength-plasticity synergy

Titanium (Ti) is a promising candidate for biomedical implants due to lightweight, superior corrosion resistance and biocompatibility. Nevertheless, pure Ti is confronted with poor wear resistance which poses a profound bottleneck for orthopedic implant applications. In this work, a novel and feasible route of mechanical milling (MM) and laser powder bed fusion (LPBF) was first developed for architecting highly tunable heterostructure in pure Ti, aiming to overcome wear resistance dilemma. During MM process, a spatial core-shell heterostructure within Ti particle was triggered by manipulating gradient and intense plastic deformation, accompanied with pre-existing dislocations. In subsequent LPBF process, the highly transient-melting kinetics and localized nature effectively perpetuated grain heterogeneity, hence creating a harmonic heterostructure within consolidated pure Ti. Consequently, the heterostructured Ti exhibited an excellent enhanced wear resistance (33.7%) compared to the homogeneous counterpart, which was attributed to a marvelous strength-plasticity synergy motivated by the hetero-deformation induced strengthening and strain-hardening. Furthermore, back-stress caused by geometrical necessary dislocation pile-ups offset partial wear shear-stress, also contributing to wear resistance enhancement. This study not only provides a manoeuvrable and paradigm route to fabricate Ti with conspicuous strength-plasticity synergy and wear resistance, but also sheds light on developing and extending cutting-edge biomedical implant applications.