Chromium precipitation from β-Ni(Al, Ti) and γ'-Ni3(Al, Ti) in the alloy (Ni70Al20Ti10)0.9Cr0.1

Abstract The crystallography and nucleation of the Cr phase (α) from both β-Ni(Al, Ti) and γ'-Ni3(Al, Ti) in an α-β-γ' three-phase alloy are investigated using analytical electron microscopy. The α particles in β are spherically shaped and oriented parallel with the parent phase. Those in γ' are lath-shaped with a well-defined habit plane of (121)γ'/(312)α, a growth direction close to [111]α/[101]γ', and are related to γ' by the Kurdjumov-Sachs (K-S) orientation relationship. It is shown that α particles can nucleate only from the disordered γ phase which was stabilized at higher temperatures. The heterogeneous nucleation and distribution of α particles in γ' are interpreted in terms of a transformation sequence. Modification of the microstructure by rapid solidification is also discussed.

[1]  D. G. Morris,et al.  Rapid solidification of Ni_3Al by Osprey deposition , 1991 .

[2]  R. Cahn,et al.  A microstructural study of a Ni_2AlTi–Ni(Al, Ti)–Ni_3(Al, Ti) three-phase alloy , 1991 .

[3]  M. Strangwood,et al.  Effects of chromium on crack growth and oxidation in nickel aluminide , 1990 .

[4]  L. Zhuang,et al.  Transmission electron microscopy study of the Osprey processed Cr-containing Ni3AlX intermetallic , 1990 .

[5]  D. G. Morris,et al.  Antiphase domain boundaries and their importance for dislocation behaviour in Ni3Al based alloys , 1990 .

[6]  D. Laughlin,et al.  Decomposition and ordering processes involving thermodynamically first-order order → disorder transformations , 1989 .

[7]  M. Enomoto,et al.  Analysis of γ′/γ equilibrium in Ni−Al−X alloys by the , 1989, Metallurgical and Materials Transactions A.

[8]  P. C. Clapp,et al.  Materials Research Society Symposium Proceedings Held in Boston, Massachusetts on 29 November-1 December 1988. Volume 133. High-Temperature Ordered Intermetallic Alloys III , 1988 .

[9]  G. Weatherly,et al.  The interphase boundary structure of precipitates in a Ni-Cr alloy , 1988 .

[10]  S. David,et al.  The effect of domain structure on the hot ductility of NiCr aluminides , 1988 .

[11]  R. Cahn,et al.  The order-disorder transformation in Ni3Al and Ni3AlFe alloys—I. Determination of the transition temperatures and their relation to ductility , 1987 .

[12]  G. Weatherly,et al.  The invariant line and precipitation in a Ni-45 wt% Cr alloy , 1987 .

[13]  Shyh-Chin Huang,et al.  L12-type Ni-Al-Cr alloys processed by rapid solidification , 1986 .

[14]  H. Aaronson,et al.  Application of the “0” lattice calculation to f.c.c./b.c.c. interfaces , 1986 .

[15]  A. Inoue,et al.  Microstructure and mechanical properties of rapidly quenched L11 alloys in Ni-Al-X systems , 1983 .

[16]  P. Kelly,et al.  The determination of foil thickness by scanning transmission electron microscopy , 1975 .

[17]  W. Bollmann.  O-Lattice calculation of an F.C.C.–B.C.C. interface , 1974 .