Phase stability and fcc/hcp martensitic transformation in Fe-Mn-Si alloys - Part I. Experimental study and systematics of the M-S and A(S) temperatures

摘要

This paper presents the first part of an experimental and thermodynamic study of the fcc/hcp relative phase stability and the fcc<->hcp Martensitic Transformation (MT) in the Fe-Mn-Si system. In the present work, the building up of an extensive experimental database is described in detail. Fe-Mn-Si alloys with 15 to 35 wt. % Mn and up to 6.5 wt.% Si are investigated. The fcc-->hcp (M-s) and the hcp-->fcc (A(s)) MT temperatures are determined using a dilatometric technique. With this new information, the composition dependence of the M-s and A(s) temperatures is established. A well defined picture of the systematics of the MT temperatures emerges from our measurements, which is critically compared with the recent calculations due to Forsberg and Agren. The need for a new assessment of the fcc/hcp relative phase stability in Fe-Mn-Si alloys is emphasized. (C) 1998 Elsevier Science S.A. All rights reserved. [References: 26]