Jean-Marie Dubois

Abstract:

We draw attention to A-B-C ternary alloys, in which the elemental constituents A, B and C are chosen in such a way that B-C interactions are repulsive, but A-B and A-C are attractive in the respective binary systems. Such “push-pull alloys” are reminiscent of amplifiers designed to amplify electric signals. Push-pull alloys amplify complexity, forming complex intermetallics with tens to thousands of atoms per unit cell. Few of them lead to the ultimate degree of complexity when quasiperiodic order substitutes for crystal periodicity, which opens the way to discovering unprecedented properties such as heat insulation in Al62Cu25Fe13 (at. %). Many more compounds are known today, which share the same elemental characteristics (the picture may be extended to specific binary alloys). The case of push-pull alloys will be exemplified with data obtained on several ternary systems such as Gd-Ca-Cu and Al-Sc-Cr alloys as well as magnetic materials based on (Gd,Al)-Cu-Fe metallic glasses.