CRYSTALLOGRAPHIC TEXTURE-DEPENDENT DISSOLUTION OF THERMOMECHANICALLY PROCESSED BIODEGRADABLE PURE IRON

Abstract

Low in vivo dissolution rate is a major setback in the use of pure iron (Fe) as a biodegradable metallic implant material. Many methods employed to overcome this major limitation modify microstructure, which in turn moderate dissolution kinetics. Crystallographic texture is one of such microstructural parameters. This work demonstrates a relationship between the texture strength of crystallographic planes and the in vitro dissolution rate of pure Fe in simulated body fluid (Hanks’ solution). Pure Fe samples were subjected to thermomechanical processing-cold rolling and recrystallization annealing. The developed crystallographic textures were characterized with X-ray diffractometer (XRD). The corrosion rates were determined in Hank’s solution using Potentiodynamic polarization test. The result indicated that the deformation textures which were predominantly {200}, reverted to different intensities of {110}, {200} and {211} after recrystallization annealing. (110), (200) and (211) textures had significant effects on the corrosion current density. Corrosion current increased as the texture strengths of (110) and (211) increased, but decreased as the texture strength of (200) increased. For enhanced dissolution rate, a processing technique that would lead to increase and decrease in texture strengths of (110) and (200) respectively in pure iron should be sought.