Microstructure, mechanical properties, degradation behavior, and biocompatibility of porous Fe-Mn alloys fabricated by sponge impregnation and sintering techniques

In this study, porous iron (Fe)–manganese (Mn) alloys with high porosity were successfully prepared by sponge impregnation and sintering (SIS). The compositions of the porous Fe–Mn alloys were strongly dependent on the sintering temperature, and the Mn content was ~44, 30, and 12 wt.% for alloys sintered at 1100, 1150, and 1200 °C, respectively. The porous Fe–Mn alloys exhibited a well-interconnected porous structure with ~85% porosity and average pore size ranging from 375 to 500 um. The porous Fe-44Mn and Fe-30Mn alloys were mainly composed of a γ-austenite phase, while the porous Fe-12Mn was composed of an α-ferrite phase. The yield strength and elastic modulus of the porous Fe–Mn alloys ranged from 6 to 10 MPa and from 0.12 to 0.37 GPa, respectively, similar to those of cancellous bone. The degradation rate of the porous Fe–Mn alloys decreased over time during immersion in simulated body fluid (SBF), and was 1.0 mm/year for Fe-44Mn, 0.81 mm/year for Fe-30Mn, 0.41 mm/year for Fe-12Mn, and 0.33 mm/year for pure Fe after 14 d SBF immersion. Moreover, the porous Fe–Mn alloys exhibited good biocompatibility with clearly enhanced cell proliferation after direct culturing of osteoblastic MC3T3-E1 cells for 7 d. Thus, these porous Fe–Mn alloys can be anticipated to be promising biodegradable implant materials. Statement of Significance: This work reports on porous Fe-Mn alloys with high porosity, suitable mechanical properties and degradation rate, and good biocompatibility. The porous alloys prepared by sponge impregnation and sintering exhibited a well-interconnected porous structure with ~85% porosity and average pore size ranging from 375 to 500 um. The yield strength and elastic modulus of the porous alloys ranged from 6 to 10 MPa and from 0.12 to 0.37 GPa, respectively, similar to those of cancellous bone. The degradation rates in simulated body fluid (SBF) were ~1.0 mm/year for Fe-44Mn, 0.81 mm/year for Fe-30Mn, and 0.41 mm/year for Fe-12Mn, respectively. Moreover, the porous Fe-Mn alloys exhibited good biocompatibility with enhanced cell proliferation after direct culturing of osteoblastic MC3T3-E1 cells