3D neutron depolarization experiments on the gamma/alpha phase transformation in steel

Three-dimensional neutron depolarization experiments have been performed in order to study the isothermal phase transformation from austenite (gamma-F e) into ferrite (alpha-Fe) in medium-carbon steel. The polarization rotatio n during transmission through the sample is a measure of the ferromagnetic ferrite fraction, while the degree of depolarization determines the charact eristic length scale of the ferrite microstructure. The application of a ni ckel coating is found to suppress ferrite formation at the surface, which a llows for a direct analysis of the bulk transformation kinetics. (C) 2000 E lsevier Science B.V. All rights reserved.