Solidification paths and eutectic intermetallic phases in Mg–Al–Ca ternary alloys

The solidification of Mg–Al–Ca ternary alloys in the α-Mg solidification region was investigated by microstructural and thermal analysis, and the liquidus projection was determined. The liquidus temperature decreases with additions of Al and Ca. Solidification is terminated with the formation of C14...

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Bibliographic Details
Published in:Acta materialia 2005-05, Vol.53 (9), p.2823-2834
Main Authors: Suzuki, A., Saddock, N.D., Jones, J.W., Pollock, T.M.
Format: Article
Language:English
Subjects:
Aluminum
Applied sciences
Eutectic temperature
Exact sciences and technology
Invariants
Laves phases
Liquidus
Liquidus projection
Magnesium alloys
Magnesium base alloys
Metals. Metallurgy
Phase transformations
Solidification
TEM
Ternary alloys
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Summary:The solidification of Mg–Al–Ca ternary alloys in the α-Mg solidification region was investigated by microstructural and thermal analysis, and the liquidus projection was determined. The liquidus temperature decreases with additions of Al and Ca. Solidification is terminated with the formation of C14 (Mg 2Ca), C36 ((Mg,Al) 2Ca) or A12 (β-Mg 17Al 12) eutectic compounds, in the order of increasing Al content. The L → α + C36 eutectic has a saddle point at 807 K, and with decreasing temperature, two ternary invariant transformations, L → α + C14 + C36 (787 K) and L + C36 → α + A12 (725 K) are observed. The stability of the intermetallic C36 phase during annealing at 573 K was examined in die-cast Mg–5Al–3Ca based alloys. The C36 phase transformed to the C15 (Al 2Ca) phase by a shear-assisted mechanism.
ISSN:1359-6454
1873-2453
DOI:10.1016/j.actamat.2005.03.001