| A mathematical approach using the phenomenological theory, originally developed by Kajiwara for Cubased shape memory alloys, has been applied to the bcc-to-9R martensitic transformation in Fe-0.15C-1.5Mn-1.5Si-1.0Cu alloy. Analytical equations for the lattice invariant shear and habit plane were derived, and the calculated values of the lattice invariant shear and habit plane were g`=0.09669 and (0.34179, ±0.80472, 0.48539)_bcc, respectively. The orientation relationship between the ferrite matrix and 9R precipitate was calculated using the transformation matrix as follows: [110]_9R//[1.00131, -1.00379, 1.00186]_bcc and (114)_9R//(0.07769, 1.07566, 1,00008)_bcc The deviation angles of orientation relationship between the calculated and the measured by HRTEM were found to be 0.06071 in direction and 3.67590 in plane, respectively. The present model successfully predicted the crystallographic features of bcc-to-9R martensitic transformation in ferritic steels. |
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