Effects of pore-forming agents on microstructure and properties of biomedical porous Ti/16Mg composites

The biomedical porous Ti/16Mg composite materials with the elastic modulus close to that of human bone and the strength meeting the requirements of human implants were prepared by powder metallurgy combined with microwave sintering method in this paper. The effects of particle size and addition amount (mass fraction) of NH₄HCO₃ pore-forming agents on the microstructure, mechanical properties, and corrosion resistance of the composites were investigated by scanning electron microscopy, X-ray diffraction, metallography, compression test, and corrosion resistance test. The results show that NH₄HCO₃ has no significant effect on the phase composition of porous Ti/16Mg composites. The pore size increases with the increase of NH₄HCO₃ particle size, and the porosity increases from 16.64% to 33.09% with the increase of NH₄HCO₃ mass fraction. When the particle size of NH₄HCO₃ is 165~198 μm and the mass fraction is 18%, the elastic modulus of the porous Ti/16Mg composites is 6.49 GPa and the compressive strength is 115 MPa, which can meet the mechanical property requirements of human implants. Particle size of NH₄HCO₃ has little effect on the corrosion resistance of the porous Ti/16Mg composites. With the same particle size, the corrosion resistance of the porous Ti/16Mg composites decreases slightly and the polarization resistance decreases from 574.528Ω·cm^‒2 to 139.236Ω·cm^‒2 with the mass fraction of NH₄HCO₃ increasing from 0 to 24%.