First-principles investigation of activity and solubility of Si in Mo solid solution

Abstract

The activity and solubility of Si in Mo solid solution were studied by the first-principles calculations and quasi-harmonic approximation. The lattice constants, bulk modulus, and formation enthalpies of Mo-Si intermetallics were investigated, and the thermodynamic properties of Mo were also calculated. The Si activity coefficient [Formula: see text] is approximately 10[Formula: see text] at 100 K, while it increases by about 15 orders of magnitude over the investigated temperature range (100–2000 K). It is clear that Si activity coefficient in Mo solid solution increased rapidly with the increasing temperature, which should be ascribed to the Si–Mo interaction being evidently stronger than Mo–Mo interaction. According to the calculated thermodynamic properties, the solubility curve of Si in Mo solid solution was also predicted. The solubility limit of Si in Mo solid solution is [Formula: see text]5.5 at.%, which agrees well with the other experiment and assessed results.

Effect of Alloying Elements on the Mechanical Properties of Mo3Si

“…The electronic configurations of elements were: Mo 4p 6 4d 5 5s 1 , Si 3s 2 3p 2 , Cr 3d 5 4s 1 , Nb 4s 2 4p 6 4d 4 5s 1 , V 3p 6 3d 4 4s 1 , W 5p 6 5d 4 6s 2 , Al 3s 2 3p 1 , Ga 3d 10 4s 2 4p 1 , and Ge 3d 10 4s 2 4p 2 . The energy cut-off was 420 eV, which was considered enough in our early research [18,20].…”

“…However, the alloying influences on the mechanical behaviors of Mo3Si are still limited, especially these neighboring elements of silicon in the periodic table. Only these lattice constants [20] and some thermodynamic properties [20,21] of Mo3Si have been investigated using first-principles calculations. This work analyzed the elastic properties of Mo3Si alloyed with different concentrations of Cr, Nb, V, W, Al, Ga, and Ge from first-principles calculations.…”