Microstructure and degradation behavior of forged Fe–Mn–Si alloys

Abstract

This work presents a comparative study of a series of Fe – Mn – Si alloys proposed as degradable biomaterials for medical applications. Five Fe -28wt.% Mn -x Si (where x = 0 to 8 wt.%) alloys were fabricated by an arc-melting method. All the as-cast alloys were subsequently subjected to homogenization treatment and hot forging. The microstructure and phase constituents were investigated. It is found that the grain size of the as-forged alloys ranged approximately from 30 to 50 μm. The as-forged Fe – Mn – Si alloys containing Si from 2 to 6 wt.% was comprised of duplex martensitic ε and austenitic γ phases; however, the Si -free and 8 wt.% Si alloys only consisted of a single γ phase. After 30 days of static immersion test in a simulated body fluid (SBF) medium, it is found that pitting and general corrosion occur on the sample surfaces. Potentiodynamic analysis reveals that the degradation rate of the Fe – Mn – Si alloys increased gradually with Si content up to 6 wt.%, beyond which the degradation slows down.