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Re-investigation of phase equilibria in the system Al-Cu and structural analysis of the high-temperature phase η₁-Al_1-δCu.

ABSTRACT: The phase equilibria and reaction temperatures in the system Al-Cu were re-investigated by a combination of optical microscopy, powder X-ray diffraction (XRD) at ambient and elevated temperature, differential thermal analysis (DTA) and scanning electron microscopy (SEM). A full description of the phase diagram is given. The phase equilibria and invariant reactions in the Cu-poor part of the phase diagram could be confirmed. The Cu-rich part shows some differences in phase equilibria and invariant reactions compared to the known phase diagram. A two phase field was found between the high temperature phase η₁ and the low temperature phase η₂ thus indicating a first order transition. In the ζ₁/ζ₂ region of the phase diagram recent findings on the thermal stability could be widely confirmed. Contrary to previous results, the two phase field between δ and γ₁ is very narrow. The results of the current work indicate the absence of the high temperature β₀ phase as well as the absence of a two phase field between γ₁ and γ₀ suggesting a higher order transition between γ₁ and γ₀. The structure of γ₀ (I-43m, Cu₅Zn₈-type) was confirmed by means of high-temperature XRD. Powder XRD was also used to determine the structure of the high temperature phase η₁-Al_1-δCu. The phase is orthorhombic (space group Cmmm) and the lattice parameters are a = 4.1450(1) Å, b = 12.3004(4) Å and c = 8.720(1) Å; atomic coordinates are given.

SUBMITTER: Ponweiser N

PROVIDER: S-EPMC4825592 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Re-investigation of phase equilibria in the system Al-Cu and structural analysis of the high-temperature phase η₁-Al_1-δCu.

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Re-investigation of phase equilibria in the system Al-Cu and structural analysis of the high-temperature phase η1-Al1-δCu.

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Re-investigation of phase equilibria in the system Al-Cu and structural analysis of the high-temperature phase η₁-Al_1-δCu.