Analysis of controlled-mechanism of grain growth in undercooled Fe–Cu alloy

An analysis of controlled-mechanism of grain growth in the undercooled Fe–4 at.% Cu immiscible alloy was presented. Grain growth behavior of the single-phase supersaturated granular grains prepared in Fe–Cu immiscible alloy melt was investigated by performing isothermal annealings at 500–800 °C. The thermo-kinetic model [Chen et al., Acta Mater. 57 (2009) 1466] applicable for nano-scale materials was extended to the system of micro-scale undercooled Fe–4 at.% Cu alloy. In comparison of pure kinetic model, pure thermodynamic model and the extended thermo-kinetic model, two characteristic annealing time (t1 and t2) were determined. The controlled-mechanism of grain growth in undercooled Fe–Cu alloy was proposed, including a mainly kinetic-controlled process (t ≤ t1), a transition from kinetic-mechanism to thermodynamic-mechanism (t1 < t < t2) and purely thermodynamic-controlled process (t ≥ t2).

► In terms of a thermo-kinetic model applicable for micro-scale undercooled Fe–4 at.% Cu alloy, grain growth behavior of the single-phase supersaturated granular grain was investigated.
► In comparison of pure kinetic model, pure thermodynamic model and the extended thermo-kinetic model, two characteristic annealing time were determined.
► The controlled-mechanism of grain growth in undercooled Fe–Cu alloy was proposed, including a mainly kinetic-controlled process, a transition from kinetic-mechanism to thermodynamic-mechanism and purely thermodynamic-controlled process.