Kinetics of MnS precipitate coarsening in 3pct Si-Fe sheet

Abstract

The growth kinetics of MnS in a 3 pct Si-Fe matrix containing excess manganese were characterized at temperatures of 925°, 975°, and 1025°C by an electron microscopy extraction replica technique. The average radius of coarsened particles at timet, •rt, exhibited Greenwood’s predicted dependence for diffusion-controlled coarsening; namely, r3t= r3 0+kt where r-o is the critical radius for growth andk is the rate constant. Growth rates compared favorably to those calculated from diffusion-controlled coarsening theories assuming that growth was controlled by the diffusion of sulfur. The experimentally determined activation for coarsening, ~67 kcal, was attributed to the sum of the activation for the dissolution of MnS, ~24 kcal, and for the diffusion of sulfur, ~49 kcal.