Shape memory alloys

Claim 2

A shape memory alloy of the beta-brass type structure consisting essentially of, by weight ratio, 2 to 15% aluminium, 0.01 to 3% beryllium and the balance being substantially copper, with impurities being inevitably present in the process of preparation, said alloy having a composition range encircled by a closed line ACEFA in FIG. 1 where, by weight ratio, A: 2% aluminium, 3% beryllium, the balance copper; C: 9.0% aluminium, 0.01% beryllium, the balance copper; E: 15% aluminium, 0.01% beryllium, the balance copper; and F: 13.5% aluminium, 1.25% beryllium, the balance copper.

Claim 3

A shape memory alloy of the beta-brass type structure consisting essentially of, by weight ratio, 2 to 15% aluminium, 0.01 to 3% beryllium, and 0.05 to 15% zinc and the balance being substantially copper, with impurities being inevitably present in the process of preparation, said alloy having a composition range encircled by a hexahedron defined by vertices IJKLMNOP in the quaternary system of Cu-Al-Be-Zn of FIG. 2 where, by weight ratio, I: 2% aluminium, 3% beryllium, 0.05% zinc, the balance copper; J: 9% aluminium, 0.01% beryllium, 0.05% zinc, the balance copper; K: 15% aluminium, 0.01% beryllium, 0.05% zinc, the balance copper; L: 13.5% aluminium, 1.25% beryllium, 0.05% zinc, the balance copper; M: 1.7% aluminium, 2.6% beryllium, 15% zinc, the balance copper; N: 3.4% aluminium, 0.01% beryllium, 15% zinc, the balance copper; O: 13.0% aluminium, 0.01% beryllium, 15% zinc, the balance copper; and P: 11.5% aluminium, 1.1% beryllium, 15% zinc, the balance copper.

Claim 4

A shape memory alloy of the beta-brass type structure consisting essentially of, by weight ratio, 2 to 15% aluminium, 0.01 to 3% beryllium, and 0.05 to 15% zinc and the balance being substantially copper, with impurities being inevitably present in the process of preparation, said alloy having a composition range encircled by a hexahedron defined by vertices IJKLMNOP in the quaternary system of Cu-Al-Be-Zn of FIG. 2 where, by weight ratio, I: 2% aluminium, 3% beryllium, 0.05% zinc, the balance copper; J: 9% aluminium, 0.01% beryllium, 0.05% zinc, the balance copper; K: 15% aluminium, 0.01% beryllium, 0.05% zinc, the balance copper; L: 13.5% aluminium, 1.25% beryllium, 0.05% zinc, the balance copper; M: 1.7% aluminium, 2.6% beryllium, 15% zinc, the balance copper; N: 3.4% aluminium, 0.01% beryllium, 15% zinc, the balance copper; O: 13.0% aluminium, 0.01% beryllium, 15% zinc, the balance copper; and P: 11.5% aluminium, 1.1% beryllium, 15% zinc, the balance copper.

Claim 5

The alloy as recited in claim 1, which can be cold-worked, and has a composition range encircled by a closed line BCDGHB of FIG. 1 where, by weight ratio, B: 6% aluminium, 1.3% beryllium, the balance copper; D: 12% aluminium, 0.01% beryllium, the balance copper; G: 7.5% aluminium, 2.15% beryllium, the balance copper; and H: 6% aluminium, 2.4% beryllium, the balance copper.

Claim 6

The alloy as recited in claim 1 or 2, in which said inevitable impurities are contained in an amount of at most 0.5% by weight.

Claim 7

The alloy as recited in claim 4, in which said inevitable impurities are silicon, iron, cobalt, magnesium, aluminium, manganese or nickel or a mixture of two or more of these elements.

Claim 8

The alloy as recited in claim 2, which can be cold-worked, and has a composition range encircled by a heptahedron defined by vertices RJSTQNUVW in the quaternary system of FIG. 2 where, by weight ratio, R: 6% aluminium, 1.3% beryllium, 0.05% zinc, the balance copper; S: 12% aluminium, 0.01% beryllium, 0.05% zinc, the balance copper; T: 7.5% aluminium, 2.15% beryllium, 0.05% zinc, the balance copper; Q: 6% aluminium, 2.4% beryllium, 0.05% zinc, the balance copper; U: 10.2% aluminium, 2.1% beryllium, 15% zinc, the balance copper; V: 6.4% aluminium, 1.9% beryllium, 15% zinc, the balance copper; and W: 3.4% aluminium, 2.3% beryllium, 15% zinc, the balance copper.