Ternary Alloy Systems

Ternary systems consist of copper and aluminium plus one other alloying element: most commonly iron, nickel, manganese or silicon. Small additions of iron are made to copper–aluminium alloys primarily as a grain refiner in order to improve toughness and to prevent the formation of the corrosion-prone γ₂ phase. Although Copper-aluminium-iron alloys with up to 1% each of nickel and manganese are strictly speaking complex alloys, their metallurgy is very similar to that of ternary copper–alummium-iron alloys. There are no ternary Copper–aluminium–nickel alloys in common use because nickel is almost always associated with iron. At a lower temperature, where there will be a significant proportion of the α-phase present, the alloy recrystallises as it recovers from hot-working and the mechanical properties cease to be anisotropic. Opinions are divided regarding the solubility of iron at room temperature; it is not likely to be more than 1%.