Local atomic arrangements in the solid solution Al-1.7 at.% Cu, at 793 K
✍ Scribed by E. Matsubara; J.B. Cohen
- Publisher
- Elsevier Science
- Year
- 1983
- Weight
- 892 KB
- Volume
- 31
- Category
- Article
- ISSN
- 0001-6160
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✦ Synopsis
The absolute diffuse X-ray intensity, scattered from a crystal of Al-l .7 at.% Cu, was measured in the solid solution region at 793 K. This intensity was separated into terms associated with local order, and those due to displacements of atoms from the sites of the average lattice. Computer simulations with the measured short-range order parameters and for a pseudo-random alloy were compared. The actual alloy has few isolated Cu atoms, compared to the random ~n~guration. Instead the Cu is present in small composition fluctuations; more than half the solute content is in tiny plate-like regions which resemble the larger 0.P. zones that form upon quenching and aging. Also, the density of these embryonic regions is similar to the zone density for short aging times. Therefore, there is no apparent nucleation barrier for zone formation. The electrical resistivity immediately after quenching can be calculated from the cluster popufation, and the resuit agrees with experiment. The pair potentials in the system were determined from the X-my scattering. MA'JSUHARA an4 C'OI1EN: LOC'AL ATOMIC ARRANGEMENTS IN SOLID SOLUTIONS MAT!w~.JAR,.?, and COHEN: LOCAL ATOMI(.' ~\Kl~hN<iIlRlI:S~I'S IN SOi.l!) SOLUTIONS 2131