Surface and bulk order-disorder transitions
Abstract
Interrelation of surface an bulk order-disorder transitions in binary alloys A xB 1- x is discussed within the framework of the Bragg-Williams approximation, using the fcc (100) and bcc (110) surfaces as an example. In an fcc alloy with a (100) surface, layers parallel to the surface undergo alternately second-order transitions. On the other hand, the bulk fee alloy reveals a first-order transition from the disordered phase to a mixture of the disordered and the AB 3- (or A 3B-) type ordered phases except for X = 0.5. The origin of the bulk first-order transition is discussed by taking into account order-disorder transitions in the surface region. For comparison, the bulk second-order transition in a bcc alloy is also discussed.
- Publication:
-
Surface Science
- Pub Date:
- September 1991
- DOI:
- 10.1016/0039-6028(91)90676-J
- Bibcode:
- 1991SurSc.255L.579T