Solidification: Phase Formation
A conventional Scheil simulation provides an upper boundary for how far a solidification can deviate from equilibrium, therefore a real solidification is expected to occur between the equilibrium simulation and the Scheil simulation. In Thermo‑Calc performing a Scheil simulation always triggers an equilibrium simulation.
Read more about Scheil Solidification Simulations on our website, including how to select the right model for your simulation. If you are in Thermo‑Calc, press F1 to search the help to learn about using Scheil.
A206 Alloy
Figure 1: Scheil solidification of an A206 alloy (Al-4.58Cu-0.28Mg-0.51Fe-0.07Si-0.003Mn, wt.%) with the Al13Fe4 and Al6Mn phases suspended. According Liu et al. [2012Liu], the metastable AlmFe (modeled as Al4Fe) Fe phase formed after (Al) during the solidification. The phase formation sequence and phase transformation temperatures can be well accounted for with this calculation.
Alloy AA7075
Figure 2: Equilibrium solidification and Scheil solidification simulations of alloy AA7075, compared with experimental results [1990Bac]. (Al), Al13Fe4, Mg2Si, T-Phase and V-Phase (MgZn2) are found in the microstructure as predicted from the calculation. Al45Cr7 forms primarily as a Cr-bearing phase, which may have been overlooked in experimental investigation due to its small amount. S-Phase was shown at the late stage of the Scheil solidification and its amount is small. Al2Cu was experimentally observed but not shown in the calculation.
References
[1990Bac] L. Backerud, G. Chai, J. Tamminen, Solidification Characteristics of Aluminum Alloys in Foundry Alloys, Volume 1 and 2 (American Foundrymen’s Society, Inc., 1990), p. 266.
[2012Liu] K. Liu, X. Cao, X. G. Chen, A New Iron-Rich Intermetallic-Al m Fe Phase in Al-4.6Cu-0.5Fe Cast Alloy. Metall. Mater. Trans. A. 43, 1097–1101 (2012).