Friday, December 7, 2012

1212.1250 (Kumar Ankit et al.)

Computational study of pearlite growth in diffusion controlled regime    [PDF]

Kumar Ankit, Abhik Choudhury, Cheng Qin, Sebastian Schulz, Malte McDaniel, Britta Nestler
We investigate the lamellar growth of pearlite at the expense of austenite during the eutectoid transformation in steel. To begin with, we extend the Jackson-Hunt-type calculation, done previously for eutectic transformation, to eutectoid transformation by accounting for diffusion in austenite as well as ferrite. It is predicted, that growth from austenite as well ferrite leads to the formation of tapered cementite along with an overall increase in the transformation kinetics as compared to growth from austenite (only). The difference in the dynamics is described by a factor '\rho' which comprises of the ratio of the diffusivities of the bulk and the growing phases, along with the ratios of the slopes of the phase co-existence lines. Next, we carry out phase-field simulations to test the accuracy of analytically derived growth velocity as a function of lamellar spacing at constant undercooling. It is found that the derived velocity for pearlite growth by Jackson-Hunt-type analysis is in reasonable agreement with the phase-field results.
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