Precipitation and Ostwald ripening in dilute Al base-Zr-V alloys

Technical Report · Mon Dec 01 04:00:00 EST 1986

OSTI ID:6326417

Zedalis, M S; Fine, M E

The coarsening rates of both cubic and tetragonal aluminum zirconium precipitates in aluminum were measured. The tetragonal Al/sub 3/Zr coarsened 16 times faster than the cubic modification in keeping with the fact that the latter is coherent and coplanar with the matrix while the former forms a semi-coherent interface with the matrix giving a larger interfacial energy. Partial substitution of vanadium zirconium reduced the precipitate-matrix mismatch for both phases and slowed both coarsening rates as well as retarded the cubic-to-tetragonal transformation. Reducing strain and interfacial energy no doubt is the origin of this effect. Since the cubic particles are spherical, their volume fraction is small and the coherency strains are small: this would appear to be an ideal system for testing the Lifshitz-Sylozov-Wagner theory of diffusion-controlled Ostwald ripening. While the theory seems to hold, the calculated diffusivity of Zr in Al is much higher than the value reported in the literature. Because of the low coarsening rates of the dispersed particles, the aluminum-zirconium-vanadium system shows promise as the basis for a high-temperature Al alloy.

• Research Organization: Northwestern Univ., Evanston, IL (USA). Dept. of Materials Science and Engineering
• OSTI ID: 6326417
• Report Number(s): AD-A-179808/1/XAB
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102* -- Metals & Alloys-- Structure & Phase Studies
ALLOYS
ALUMINIUM ALLOYS
ALUMINIUM BASE ALLOYS
DIFFUSION
DILUTION
DISPERSIONS
HIGH TEMPERATURE
INTERFACES
MIXTURES
PHASE STUDIES
PRECIPITATION
SEPARATION PROCESSES
SOLID SOLUTIONS
SOLUTIONS
SURFACE PROPERTIES
THERMODYNAMICS
VANADIUM ALLOYS
ZIRCONIUM ALLOYS