TY - JOUR

T1 - Domain walls in bcc to hcp reconstructive phase transformations

AU - Saxena, Avadh

AU - Sanati, Mahdi

AU - Albers, R. C.

N1 - Funding Information:
The authors thank G.R. Barsch for providing invaluable input and useful references as well as for very insightful discussions. This work was supported by the US Department of Energy.

PY - 1999/12/15

Y1 - 1999/12/15

N2 - The bcc (body-centered cubic) phase to hcp (hexagonal closed pack) phase transformation in certain elements (e.g. Ti) and alloys is induced either by quenching or application of pressure. To study domain walls in these materials we have extended the Landau model of Lindgård and Mouritsen by including a spatial gradient (Ginzburg) term of the scalar order parameter. Through first-principles calculations, we show that the bcc structure is unstable with respect to the shuffle of atoms rather than the shear. Therefore, we can reduce the multiple (two) order parameter (OP) Landau free energy (LFE) to an effective one OP (shuffle) potential, which is a reasonable approximation. In general, the effective LFE is a triple-well potential. From the variational derivative of the total free energy we obtain a static equilibrium condition. By solving this equation for different physical parameters and boundary conditions, we obtain different quasi-one-dimensional soliton-like solutions which correspond to four types of domain walls between the bcc phase and the hcp phase.

AB - The bcc (body-centered cubic) phase to hcp (hexagonal closed pack) phase transformation in certain elements (e.g. Ti) and alloys is induced either by quenching or application of pressure. To study domain walls in these materials we have extended the Landau model of Lindgård and Mouritsen by including a spatial gradient (Ginzburg) term of the scalar order parameter. Through first-principles calculations, we show that the bcc structure is unstable with respect to the shuffle of atoms rather than the shear. Therefore, we can reduce the multiple (two) order parameter (OP) Landau free energy (LFE) to an effective one OP (shuffle) potential, which is a reasonable approximation. In general, the effective LFE is a triple-well potential. From the variational derivative of the total free energy we obtain a static equilibrium condition. By solving this equation for different physical parameters and boundary conditions, we obtain different quasi-one-dimensional soliton-like solutions which correspond to four types of domain walls between the bcc phase and the hcp phase.

KW - Bcc/hcp

KW - Domain walls

KW - Landau-Ginzburg model

KW - Reconstructive phase transformations

KW - Shear/shuffle

UR - http://www.scopus.com/inward/record.url?scp=0004408864&partnerID=8YFLogxK

U2 - 10.1016/s0921-5093(99)00376-7

DO - 10.1016/s0921-5093(99)00376-7

M3 - Article

AN - SCOPUS:0004408864

VL - 273-275

SP - 226

EP - 230

JO - Materials Science and Engineering A

JF - Materials Science and Engineering A

SN - 0921-5093

ER -