Sage Journals: Discover world-class research

Abstract

The system Ni₃Ta-Ni₃Al, a superalloy, has been of interest recently for use as a high temperature material. Uses are suggested as a reinforced eutectoid composite. The phase diagram of this alloy is unknown but is believed to be similar to that of the Ni₃Al-Ni₃Nb. A computer method is applied utilizing a suitable program to evaluate the temperatures and compositions around the experimental T_e of 1633 K. The results of such a simulation show that the equilibrium composition of NiAl undergoes a substantial variation about this temperature, however the edge solutions differ from the theoretical stoichiometry possibly due to depletion of one or more components at the matrix-ppt (γ', δ") interface which could result in misalignment of the phase boundaries. Addition of quaternary elements may improve this and also the corrosion resistance at elevated temperatures.

Get full access to this article

View all access options for this article.

References

F.D. Lemkey and G. McCarthy , NASA CR-134678, NASA Washington, DC, USA, 1975. 2. L. Kaufman and H. Nesor , Canadian Met. Qtly, 14, 3, 221 (1975).

J.C. Hubert , W. Kurz et al, Jnl. Crystal growth, 13/14, 757 (1972).

J.C. Hubert , F.R. Mollard et al, Proc. Conf. on in situ Composites, V2, NMAB 308.II p. 323, (National Academy of Sciences , Washington, DC, USA) 1973.

E.R. Thompson and F.D. Lemkey , Trans ASM, 62, 140, (1969 ).

L. Kaufman and H. Bernstein , 'Computer calculatons of phase diagrams,' Academic Press , N.Y.C. 1970.

C.J. Smithells , 'Metals Reference Book,' 5th ed. Butterworths, Boston, 1976.

R. Hultgren et al, 'Selected Values of the Thermodynamic Properties of Binary Alloys ,' John Wiley, NYC, (1965).

Computer Estimation of the Eutectic Point for Ni3Ta - Ni3Al

Abstract

Get full access to this article

References