Ternary Phase Diagrams of Aluminum with Alkaline-Earth Metals

• Published in: Metal science and heat treatment 2002-09, Vol.44 (9-10), p.413-413
• Main Authors: Ganiev, I N, Vakhobov, A V, Khakdodov, M M, Nazarov, Kh M
• Format: Article
• Language: English
• ISSN: 0026-0673; 1573-8973
• DOI: 10.1023/A:1021919721030

The absence of phase diagrams, which are the basis for choosing alloy compositions, has hindered the use of alloys of barium, strontium, and alkaline-earth metals. We used x-ray phase, microscopic diffraction, differential thermal, and potentiodynamic methods of analysis for plotting ternary phase diagrams with alkaline-earth metals (AEM). We studied the Al-Cu-Sr(Ba), Al-Ca-(Sr,Ba), Al-Si-Sr(Ba), and Al-Ge-Sr(Ba) systems. In the Al-Si(Ge)-Sr(Ba) system we confirmed the presence of MSiAl2, M(Al,Si)2, MGe2Al2, and M(Al,Ge)2 intermetallic compounds. For the first time we determined the existence of Sr3Al2Ge2 and Sr57Al30Ge13 intermetallics in the Sr-Al-Ge system. We plotted the projection of the liquidus surfaces. The aluminum solid solution was shown to be in equilibrium with SrAl2Si2 and Sr2Al2Ge2 intermetallics. These aluminum compounds form phase diagrams of eutectic type. In the Al-Cu-Sr(Ba) system we confirmed the presence of a ternary intermetallic with a variable composition that crystallized over the isoconcentration of 7.1 at.% of the alkaline-earth metal. We plotted projections of liquidus surfaces and a part of the phase diagram adjoining the binary Al-Cu system. The ternary intermetallic with a variable composition was shown to melt congruently and to form an eutectic phase diagram with aluminum and SrAl4 and BaAl4 compounds. We did not determine the existence of ternary intermetallic compounds in the Al-Li-Ca(Sr,Ba) system. All the Al-AEM binary compounds were in double equilibrium with the lithium-base solid solution.