Question

(a) Design, by stating the composition, a Cu-Ni alloy that will be completely solid at 1200°C (use Fig. 9.3a). (b) Design, by stating the composition, a Cu-Ni alloy that will exist at a completely molten state at 1300°C and becomes completely solid at 1200°C (use Fig. 9.3a).

Answer 1

a) For alloy of Cu-Ni to be completely solid at 1200 C we may choose any composition from: -

( 31.25% of Ni + 68.75% of Cu ) to (100% of Ni + 0% Cu) increasing linearly.

Find point D by similar triangle concept i.e.

Composition (at% Ni) 40 60 100 80 1600 2800 1500 Liquid 1453°C 2600 1400 Solidus line Liquidus line a+L 2400 1300 B 2200 1200 A 1100 2000 1085C 1000 40 60 80 20 100 Composition (wt% Ni) (Cu) (Ni) 31-2 DD Temperature (C) 20 Temperature (F)

b) Any composition lying in the shaded area may be chose for the design (b)

Composition (at% Ni) 20 60 80 100 40 1600 2800 1500 Liquid 1453°C 2600 1400 Solidus line Liquidus line +L 2400 1300 B 2200 1200 A 1100 2000 1085C 1000 60 40 80 100 (Cu) Composition (wt% Ni) (a) (Ni) Temperature (C) 20 Temperature (F)