Ab Initio Monte Carlo Simulations of the Acidic Dissolution of Stainless Steels: Further Insights into the Mechanisms

Abstract

Using Ab initio based Monte Carlo simulation techniques (AbMC), dissolution kinetics in acidic media was evaluated for different stainless steels (SS) as a function of their chemical composition, with particular attention paid to the role of transition metals series (TM). The elementary dissolution events at the atomic scale were treated as stochastic processes, from which dissolution probabilities were deduced. Two determining factors emerge as critical for the control of dissolution kinetics: the bonding energy of an alloying element in the SS matrix and its standard electrochemical potential. The first reflects the ability of an element to form stronger (Mo, Nb, Ni etc.) or weaker (Cr, Cu, Sn etc.) bonding than Fe, and the second refers to its facility to dissolve under an applied potential. High bonding energies and high standard potentials lead to a strong dissolution resistance (Mo), whereas low bonding energies and low standard potentials induce high dissolution kinetics (Sn). The intermediate situations: high-bonding energy and low standard potential (Nb) or low bonding energy and high standard potential (Cu) usually lead to moderate dissolution regimes with a strong impact on the dissolution mechanisms.