Critical evaluation and thermodynamic optimisation of the Si-RE systems: Part II. Si-RE system (RE = Gd, Tb, Dy, Ho, Er, Tm, Lu and Y)

Solidification Calculations of Precious Alloys and Al-Base Alloys for Additive Manufacturing

“…For the second case study, the quaternary Al-Mg-Si-Er system, a custom database, was developed by putting together the thermodynamic parameters of ternary systems from the literature, as outlined in Table 1. Mg-Si-Er NO (Extrapolated) YES (Mg-Si from [20], Mg-Er from [21], Si-Er from [22,24]) NO NO…”

“…This makes it possible to use the thermodynamic parameters for the binary subsystems and extrapolate them to create a database for the ternary Al-Si-Er system. However, the Si-Er binary system was assessed using a quasi-chemical model for the liquid phase [22], whereas in all other binary subsystems, a Redlich-Kister model was used [25]. For this reason, the results of the binary assessment from ref.…”

“…For this reason, the results of the binary assessment from ref. [22] cannot be directly merged into a single database and a reassessment of this binary system was carried out in this work.…”

“…The reassessment of the binary Si-Er system was carried out using the same experimental information as in ref. [22]. According to the CALPHAD method, the Gibbs energy of each phase (φ) of the system was described as:…”

“…As already introduced above, a reassessment of the binary Er-Si system was necessary in this work in order to include it in the quaternary Al-Mg-Si-Er database, as the only assessment reported in the literature (Kim et al [22]) is not compatible with the assessments of the other subsystems. The results of this re-optimization are shown below.…”