Synthesis of boronized Ti6Al4V/FHA composites by microwave sintering for dental applications

Boronized Ti6Al4V/FHA composites were prepared by microwave sintering of mixed powders of Ti6Al4V, TiB 2 , and synthesized fluorine-substituted hydroxyapatite (FHA) with variable compositions at 1050 °C for 30 min. The unique “lens effect” of microwave facilitated the in-situ transformation of nanoscale TiB 2 into TiB, serving as the reinforcing phase within the composites. Increasing the theoretical fluorine substitution in FHA from 0% to 50% caused less thermal decomposition of hydroxyapatite during sintering, promoting densification and thereby mechanical properties of the composites. However, continuous fluorine substitution to 100% led to excessive grain growth and FHA agglomeration, deteriorating the composite mechanical performance. The boronized Ti6Al4V/FHA composite produced using FHA with the theoretical fluorine substitution of 50% exhibited the highest compressive strength (397.7 MPa), proper compressive modulus (10.65 GPa) and maximum microhardness (385.3 HV). Furthermore, it showed excellent hydrophilicity and good cell adhesion, confirming its superior bioactivity for dental applications.