Temperature (°C) Qu.5 A copper-nickel alloy (Figure 2) of composition 80 wt% Ni - 20 wt% Cu is slowly heated from a temperature of 1100 °C. (a) At what temperature does the first liquid phase form? (b) What is the composition of this liquid phase? (c) At what temperature does complete melting of the alloy occur? (d) What is the composition of the last solid remaining prior to complete melting? Composition (at% Ni) 20 40 1600 1500 1400 Liquid 60 80 100 2800 1453°C 2600 Liquidus line Solidus line 2400 1300 +L B 1200 2200 a 1100 1085C 1000 0 (Cu) T 20 40 60 Composition (wt% Ni) 80 100 (Ni) Figure 2: Phase Diagram of a Cu - Ni System 2000