The Cu-Ni-Y (Copper-Nickel-Yttrium) System

Abstract

The Cu-Ni system [Massalski2] (Fig. 1) is a simple isomorphous system with a continuous liquid solution separated by a narrow two-phase region from a continuous solid solution. The face centered cubic (fcc) solid solution of Cu and Ni (c), however, undergoes a short range order transformation at temperatures less than 300 C. The Cu-Y system [Massalski2] (Fig. 2) has five intermediate phases, Cu6YðgÞ;Cu4YðdÞ;Cu7Y2ðhÞ;Cu2YðiÞ; and CuYðt1Þ; of which the d; i; and t1 phases melt congruently at 975, 935, and 935 C, respectively. The g and h phases form through peritectic reactions L + dM g at 910 C and L + dM h at 920 C. Four eutectic reactions: L $ c þ g; L $ h þ i;L $ i þ t1; and L M c + e occur at 860, 840, 830, and 770 C, respectively. e is the terminal solid solution (aY). A metastable phase of composition Cu5Y was found to form through rapid quenching of a liquid alloy. The h; i; and t1 phases are of invariant compositions. The Ni-Y system [1991Nas] (Fig. 3) has nine intermediate phases: Ni17Y2(f), Ni5Y(x), Ni4Y(j), Ni7Y2(q), Ni3Y(p), Ni2Y(k), NiY(s), Ni2Y3(w), and NiY3(n). The Ni5Y(x) and NiY(s) phases melt congruently at 1430 and 1070 C, respectively. All the other phases form through peritectic reactions: L + x M f at 1350 C, L + x M j at 1340 C, L + j M q at 1298 C, L + q M p at 1237 C, L + p M k at 1106 C, L + s M w at 820 C, and L + e M n at 902 C, where e is the terminal solid solution (Y). All the intermediate phases are of invariant compositions. Three eutectic reactions L M f + c, L M k + s, and L M w + n occur at 1085, 950, and 805 C, respectively.