Nishiyama

Nishiyama Kand Fujihira M 1988 Cis-trans reversible photoisomerization of an amphiphilio azobenzene derivative in its pure LB film prepared as polyion oomplexes with polyallylamine Chem. Lett. 1257-60... 

R. Nishiyama and co-workers, Yuki Gosei Kagaku Kyokai Shi 23, 515, 521 (1965). 

H. Nagase, K. Matsumoto, and H. Nishiyama, Yuki Gosei Kagaku Kyokaishi 54,1055 (1996). 

MI14 M. Alvarez, R. Robey, V. Sandor, K. Nishiyama, Y. Matsumoto,... 

We found that without any exception in all of our simulations Bain s lattice correspondence actually applies, i.e. one set of (110) planes of the bcc structure corresponds to a set of fee (111) planes, while the bcc [001] direction lying in these planes is transformed into the [110] direction of the fee phase. Moreover, these directions are exactly parallel to each other. This would correspond to a Nishiyama-Wassermann orientational relationship if the (110) and (111) planes would also be parallel to each other. But this is not the case. These planes are rotated around [001] by an angle between 0 and 9 during the transformation. This angle differs between the simulations in a non-systematic way. 

The orientational relationships between the martensite and austenite lattice which we observe are partially in accordance with experimental results In experiments a Nishiyama-Wasserman relationship is found for those systems which we have simulated. We think that the additional rotation of the (lll)f< c planes in the simulations is an effect of boundary conditions. Experimentally bcc and fee structure coexist and the plane of contact, the habit plane, is undistorted. In our simulations we have no coexistence of these structures. But the periodic boundary conditions play a similar role like the habit plane in the real crystals. Under these considerations the fact that we find the same invariant direction as it is observed experimentally shows, that our calculations simulate the same transition process as it takes place in experiments. The same is true for the inhomogeneous shear system which we see in our simulations. 

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