14
in question. Guard and Smith (1959-1960) reported the
presence of a ternary compound at 1000 C on the Ni-rich
side of the diagram. This phase was included in a
subsequently derived equilibrium diagram by Aigeltinger et
al. (1978). No other investigator has reported the
presence of a ternary Ni-Mo-Al compound (Bagaryatski and
Ivanovskaya, 1960; Virkar & Raman, 1969; Raman and
Schubert, 1965; Pryakhina et al., 1971; Miracle et al.,
1984).
Aigeltinger et al. (1978), Loomis et al. (1972), and
recently Miracle et al. (1984), extend the maximum
solubility of Mo in N3AI to 6.0 at. % Mo, a value much
higher than that previously reported by Guard and Smith
(1959-1960), Bagaryatski and Ivanovskaya (1960), Virkar
and Raman (1969), Raman and Schubert (1965), and Pryakhina
et al. (1971). Miracle et al. (1984) also report an
additional class II reaction at 1090 C involving gamma,
gamma prime, NiMo, and Mo. This reaction brings gamma
prime, gamma, and NiMo into equilibrium at lower
temperatures. This class II reaction was previously
unreported. A 1000 C isotherm from their work is compared
with the 600 C section from Pryakhina et al. (1971) in
Figure 2.5.
2.1.2.2 Ni-Al-Ta
The Ni-rich side of this diagram has recently been
reviewed by Nash and West (1979). They confirm the