Phase-Field Simulations and Analysis of Effect of Dispersed Particles on Migration of Delta to Gamma Transformation Interface

Abstract

Retardation effect of dispersed inert particles on delta-gamma interface migration in carbon steels during isothermal delta to gamma transformation is analyzed by two-dimensional phase-field simulations. The effect is systematically investigated for different values of particle radius, r, particle spacing, l, and initial carbon concentration of delta phase. The retardation effect becomes stronger when the pinning parameter described by r/l 2 is larger and the carbon concentration of delta phase is higher, indicating that delta to gamma transformation kinetics can be retarded in a similar way to the pinning effect on grain growth kinetics.

A role of interfacial energy balance in delta to gamma transformation kinetics in carbon steel with dispersed second phase particles analyzed by phase-field simulation

“…The existence of the retardation effect was found in our previous study on isothermal d to c transformation by a diffusion-couple experiment [3]. In addition, two-dimensional phase-field simulations were carried out to investigate the details of this retardation effect [3,4]. It was shown that the retardation effect becomes stronger with the increase in a parameter, r/l 2 , where r is the size and l is the spacing of the particles.…”

“…The detailed explanation of this model can be found in several articles [13][14][15] and our previous paper [4]. We will briefly explain the model here.…”

“…In our previous studies, we proposed a new way for lowering T c [3,4]. It is based on a retardation effect due to second-phase particles on the migration of d-c interface [3,4].…”

“…In our previous studies, we proposed a new way for lowering T c [3,4]. It is based on a retardation effect due to second-phase particles on the migration of d-c interface [3,4]. If the second-phase particles exist in d phase, these particles are expected to retard the migration of d-c interface as is similar to the pinning effect on the grain growth [5][6][7][8][9] and accordingly T c should be lowered.…”

“…The balance of these interfacial energies denoted by r Pd , r Pc and r dc should affect the magnitude of the retardation effect. In our previous study [4], the simulations were conducted for the condition that all the interfacial energies, r dc , r Pc and r Pd , are equal. However, the different two matrix phases, d and c, have different crystal structures and hence r Pd and r Pc are basically different in reality.…”