A series of isovelocity experiments was performed to investigate the interface morphology evolution during the solid-state ferrite-austenite transformation of the Fe-Mn-Al alloy, and a quantitative relationship between cellular spacing and growth velocity had been measured. The corresponding cellular spacing of the product phase decreases with the growth velocity increasing. Theoretical model modified from directional solidification process was also applied to study the relationship between cellular spacing and growth velocity, and the theoretical prediction corresponds well with the measured results. (C) 2009 Elsevier B.V. All rights reserved.