Thermodynamic Properties of Ni-Ti-Si Ternary Alloy and Calculation of Amorphous Formation Range
The formation enthalpy △H,excess entropy SE,excess Gibbs free energy GE,and activity of each constituent element of Ni-Ti-Si ternary alloy at 1 273 K is calculated based on Chou model,and the formation enthalpies of 8 intermetallic compounds of the Ni-Ti-Si ternary alloy are calculated.The amorphous formation range of Ni-Ti-Si ternary alloy at 1 273 K is predicted based on Toop model.The calculated results show that when xNi=0.39,xTi=0.25,and xSi=0.36,the Ni-Ti-Si ter-nary alloy has the minimum △H,SE and GE,and △Hmin=-56.25 kJ/mol,SEmin=-6.38 J/mol,and GEmin=-48.14 kJ/mol.Of the 8 intermetallic compounds,the △H of the intermetallic compound τ1 is the most negative,indicating that its phase stability is the highest.It is the first to precipitate,τ2,τ6,τ7 and T8 are the next,and τ3,τ4 and τ5 are the last.Ni-Ti-Si ternary sys-tem has a very large negative deviation between the activity values of each constituent element and the ideal melt.Amorphous can be formed in the Ni-Ti-Si ternary alloy,and the amorphous formation range is very large,mainly in the composition range of xTi=20％～80％and xNi=15％～90％.The calculated range of intermetallic compounds and amorphous formation range of Ni-Ti-Si ternary alloy are in good agreement with the experimental results.
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