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.