Fe-reinforced TTCP biocermet prepared via laser melting: Microstructure, mechanical properties and bioactivity

Abstract Tetracalcium phosphate (TTCP) is considered as an ideal potential implant biomaterial due to its good biodegradability, biocompatibility and bioactivity, while the insufficient mechanical properties limit its use in loading-bearing implants. In this work, TTCP-matrix biocermet scaffolds reinforced with Fe particles contents of 15, 30, 45 and 60 vol% were fabricated by selective laser melting (SLM) technology. Experimental results indicated that the introduction of Fe significantly enhances the mechanical properties of TTCP scaffold. Among them, the 45Fe/TTCP biocermet scaffold exhibited the maximum compressive strength (354.12 ± 5.2 MPa), which was about 29.8 times higher than that of pure TTCP scaffold (11.87 ± 0.64 MPa). Meanwhile, its fracture toughness and tensile strength reached 1.88 ± 0.12 MPa m1/2 and 28 ± 2 MPa, respectively, which were higher than the 1.12 ± 0.1 MPa m1/2 and 17 ± 2.1 MPa of pure TTCP scaffold. Herein, the improvement of strength and fracture toughness under compression mode was probably accomplished by the microstructural strengthening and toughening mechanisms such as the crack deflection, crack bridging, and crack tip closure. The reinforcing mechanism under tension mode was probably due to the ductile microvoid coalescence fracture, which commonly observed in the fractured surface of pure Fe under tensile loading. Besides, the biocermet scaffold also has a good ability to induce the formation of bone-like apatite. In short, the porous Fe/TTCP biocermet scaffold with significantly enhanced mechanical properties and good bioactivity is expected to be a potential candidate for load-bearing bone implants.