Compositional short range order

HJ. Eifert, B. Elschner, K.H.J. Buschow, Density of states, compositional short-range order, and stabihty of amorphous Zr Cu. alloys, Phys. Rev. B 25 (1982) 7441—7448. 

However, it is not yet clear why the ener es of the SISF and the twin boundary increase with increasing A1 concentration. To find a clue to the problem, it would be needed to make out the effects of the short-range ordering of A1 atoms in excess of the stoichiometric composition of the HAl phase on the energies of planar faults and the stmcture of dislocation cores in the Al-rich HAl phase. 

In order to derive activity-composition relationships for ThMgAl206 in clinopyroxene, Landwehr et al. (2001) used a mixing-on-sites model assuming complete short-range order between M and T sites. The activity of ThMgAl206 in clinopyroxene is thus given by ... 

Figure IX Variation of short-range order (sro) (a) in an f.c.c. lattice above the critical temperature, as evidenced by the specific heat predicted by various ordering m els (Kikuchi 1977) and (b) sro characteristics for b.c.c. and f.c.c. structures at the equiatomic composition (Kikuchi and Saito 1974).

Fundamentally based ordering models which consider short-range ordering phenomena are rarely incorporated in CALPHAD software, and this is another area which the authors would like to see expanded. However, before this can be done in a general fashion, it is clear that ordering models need to be made more flexible, while retaining a sound physical basis, and that vibrational entropy as well as complex compositional effects must be included. 

---