Using the Al-Ni binary system to explore the potentialities of first-principles quantities

S. TUMMINELLO; M. PALUMBO; T. HAMMERSCHMIDT; R. DRAUTZ; S. SOMMADOSSI; N. DUPIN; G. FRIES

Loano

Conferencia; Conference on computer coupling of phase diagram and termochemistry; 2015

Universita degli Studi di Genova , I.E.N.I, A.S.EN.

The Al-Ni binary system is the core of Ni based superalloys. It is experimentally well determined and several thermodynamic models have been used for describing the phase diagram, phase equilibria and metastabilities [1].We use this well-known system to evaluate thermodynamic properties obtained by first-principles calculations and their predicted dependence on temperature, volume and composition. Figure 1a shows the phase diagram obtained by combining formation energies at 0 K from first-principles calculations with the Bragg-Williams approximation for configurational entropy. The computed metastable fcc phases are shown in Figure 1b. For comparison, the presently accepted Al-Ni phase diagram in the TCNI6 database and the respective fcc phase diagram are shown in Figures 1c and 1d. The challenge is to find strategies to consistently include the knowledge of Figures 1a-b into the description of the experimentally assessed phase diagram. In doing so we also point out the strengths and shortcomings of the contributions from this theoretical approach [2,3].AcknowledgmentsS.T. and S.S. are grateful to the DAAD and the Argentinian Ministry of Science, Technology and Innovative Production for the financial support through a research fellowship for PhD students and the project PICT2176 RAICES, respectively.MP, JK, TH, RD, and SF acknowledge funding by the German Research Foundation (DFG) through project C1 and C6 of the collaborative research center SFB/TR 103.[1] N. Dupin et al., Calphad 25 (2001) 279.[2] M. Palumbo et al., Phys. Status Solidi B 251 (2014) 14.[3] S. G. Fries, TC Users Meeting, Aachen 2005.