Hot-deformation characteristics and extrusion of copper–nickel alloys

Abstract

Plane-strain compression tests have been carried out over the temperature range 700–1000°C on three Cu–Ni alloys containing 34, 43, and 68%Ni. The stress-strain curves at strain rates of 1 and 10 s⁻¹ all show a peak in flow stress, followed by a fall to a steady–state value, which is characteristic of the occurrence of dynamic recrystallization; the extent of the fall is, however, significantly increased by deformational heating. At 900°C and above, static recrystallization occurs in times of ≲ 1 s, leading to dislocation-free grain structures, even in quenched samples. Lubricated hot extrusion of the alloys gives pressure–distance curves similar in form to those obtained for steels. Running pressures can be calculated with reasonable accuracy using data on heat-transfer and friction conditions derived previously from hot-extrusion studies on steels.