Development of ductile long-range ordered alloys for fusion reactor systems

A series of iron-base long-range ordered (LRO) alloys with compositions (Fe,Ni,Co) ₃V are being developed for fusion reactor applications. The alloys form a cubic ordered structure similar to AuCu₃ below their critical ordering temperature. The alloys in the ordered state are ductile, with tensile elongation in excess of 35% at room temperature. Tensile tests of the ordered alloys at elevated temperatures indicate an unusually attractive mechanical behavior. Their strength, Instead of decreasing as with conventional alloys, increases with temperature because of ordering. As a result, the ordered alloys. are much stronger than type 316 stainless steel, particularly at elevated temperatures. The ordered alloys also exhibit excellent creep strength; their creep rate is lower than that of type 316 stainless steel by 3 orders of magnitude at 650°C. A combination of excellent strength and adequate ductility makes the ironbase LRO alloys uniquely attractive for high-temperature structural applications. © 1979.