LOCAL ORDER, PHASE-DIAGRAMS AND ANTIPHASE BOUNDARIES IN ALLOYS

The recent results obtained at ONERA concerning the physics of alloys are described. First the experimental and theoretical analyses of the local or short-range order are presented. They provide us with chemica l interatomic pair interactions. Ni-V and Pt-V alloys are more specifi cally considered. Once the interactions are known, predictions about p hase diagrams can be made. Applications to pseudo-binary and ternary a lloys are presented. Then, the behaviour of antiphase boundaries in or dered alloys close to the order-disorder transition is discussed, in t he case of first order (wetting phenomenon) as well as in the case of second order transitions (critical broadening). Roughening effects are also described. Finally the possibility of handling more complex effe cts: Atomic displacements, elastic effects, ordering kinetics, is brie fly discussed.