A method for forming an austempered iron composition with a nanoscale microstructure includes a step of heating an iron-carbon-silicon alloy with silicon to a first temperature that is lower than A1 for the iron-carbon-silicon alloy. The iron-carbon-silicon alloy is then adiabatically deformed such that the temperature of the iron-carbon-silicon alloy rises to a second temperature which is sufficient to form proeutectoid ferrite and austenite. The iron-carbon-silicon alloy is cooled to a first austempering temperature. The iron-carbon-silicon alloy is then heated to a second austempering temperature that is greater than the first austempering temperature to form a dual phase microstructure. Characteristically, the dual phase microstructure includes proeutectoid ferrite and ausferrite.