Speaker
Description
Keywords: CASTEP, Ni-Al, Ni-Cr, phase stability, mechanical properties
The structural properties, phase stability and elastic properties of Ni-Al and Ni-Cr compounds were systemically investigated using first principle calculations based on density functional theory. The calculations were calculated using CASTEP supercell approach with ultrasoft pseudopotential. The structures comprised of 16 and 32 atoms built using 2x2x2 BCC and FCC unit cells, respectively, were geometry optimized using cut-off energy of 500 eV with k-points of 8 x 8 x 8. The resulting predicted lattice constants were found to be in agreement with experimental trends and in accordance with the Vegard’s law for binary solid solutions in both Ni-Al and Ni-Cr systems. The calculated heat of formation for binary FCC Ni-Al solid solutions revealed higher thermodynamic stability (alloying ability) as Al concentration increased whereas the solubility of Cr in Ni was less favourable and limited to less than 25 at.% at 0K. The elastic constants of these binary solid solutions were also calculated, from which elastic moduli associated with mechanical properties were determined.
CHCP content
• Structural properties, mechanical properties and phase stability of Ni-Cr and Ni-Al compounds were achieved using CASTEP code (supercell approach) on CHPC environment.
• Code used: Materials studio (CASTEP)
• Number of atoms:16, 32
• Core count= 48
• Challenges: To track the effects of small compositional variation on the structural properties, the supercell approach was deployed. However there was long queuing time for most calculations
