ISSN:
1573-4803
Source:
Springer Online Journal Archives 1860-2000
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Abstract Microstructures of melt-spun Ni–Al alloys with compositions from 61–85 at% Ni were studied by means of transmission electron microscopy, X-ray diffraction analysis and optical microscopy. The microstructures of as-quenched ribbons exposed to cooling rates of the order of 106 K s-1 reflect the transition from primary β-NiAl to γ-Ni solidification with increasing nickel content. In 70 at% Ni alloy ribbons, martensitic NiAl grains were detected near the wheel-side surface contrasting with anomalous and lamellar eutectic microstructure in the top part. Directly ordered Ni3Al grains with single (or large) antiphase domains (APDs) and a minor eutectic fraction were observed in 75 at% Ni alloy ribbons. Samples containing 80 at% Ni exhibit mainly single-phase Ni3Al grains with 10–20 nm sized APDs indicating sequential ordering. Weak L12 ordering was even detected in 85 at% Ni ribbons which displayed ordered antiphase zones of 1 nm size. Disordered γ-(Ni) films on grain boundaries can be discounted for 80 at% Ni ribbons, but occurred near the top of 85 at% Ni samples. The results are explained in terms of the reassessed Ni–Al phase diagram employing recent corrections near to the Ni3Al composition and new results on phase formation in undercooled Ni–Al melts. © 1998 Kluwer Academic Publishers
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1004432931315
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