CHARACTERIATION AND THE CORROSION BEHAVIOR OF THE BIORESORBABLE MG-1CA ALLOY

Abstract

In recent years, the field of magnesium-based biomaterials has become popular again, owing to advances in technologies that improve corrosion control. This paper presents a comprehensive study of the effect of severe plastic deformation (SPD) on the corrosion behavior of a bioresorbable magnesium alloy in Ringer's solution. This alloy was studied in three states: the initial homogenized state, the SPD-processed state, and the state after SPD processing and subsequent annealing at 250 °C. It is shown that SPD processing leads to a very strong grain refinement in the alloy to an average grain size of about 210 nm, but the corrosion resistance values of the SPD-processed samples differ significantlyfrom those in the homogenized state (by an order of magnitude). Using the SEM method, the surface of the samples was analyzed after exposure in Ringer's saline solution. It can be seen from the surface structure that in the homogenized state a large corrosion pit emerges at the site of the eutectics and is the result of microgalvanic corrosion caused by the α-Mg-Mg2Ca interaction. For the surface of the HPT-processed sample, which demonstrated the best corrosion resistance, characteristic is the formation of specific grooves on the surface, as well as small pits in the places where the Mg2Ca particleswere located. The conducted precision studies by TEM and XRD show that such a difference in the corrosion behavior is due to the difference in the morphology and origin of the nanosized particles of second phases, as well as in the use of the electrochemical properties of the “particle – α-Mg” pair.