Prototyping Ti₂Cu intermetallic grain growth heterogeneously in Ti6Al4V matrix through laser additive manufacturing

The Ti₂Cu intermetallics compound possessing an ability to release Cu²⁺ ions has promising antibacterial properties. This research integrates experimental and computational techniques to delve into the interfacial intermetallic (IMC) formation within the Ti6Al4V/Cu system. Heat transfer analysis is performed to numerically outline the thermal history within the microstructure during laser surface alloying (power = 1000 W and scan speed = 200 mm/s), while the phase field method is employed to describe the Ti₂Cu IMC grain growth in the Ti6Al4V matrix. As the IMC and the matrix phases respectively have free energy minima of -68.52 and -61.35 kJ/mol at T_average=1250.0 K, the growth of Ti₂Cu IMC grains at the Ti6Al4V matrix located around the depth of 5 μm from the top surface is thermodynamically favorable. Laser processing can cause the nucleation of IMC precipitates of irregular sizes and curvature profiles, in which case the curvature driven effects between the adjacent grains can additionally affect their growth kinetics. Furthermore, microbiological assays underscore the superior antibacterial efficacy of the Ti6Al4V+Ti₂Cu heterostructures as compared to the control (Ti6Al4V) counterpart.