The structural exploration of thermodynamics and dynamics in Ti-Ni liquid by ab initio molecular dynamics simulation

Abstract

In this work, we demonstrate the atomic-level understanding of thermodynamic and dynamic properties of Ti-Ni melts via ab initio molecular dynamics simulations at 2033 K. It was found that the minimum of enthalpy of mixing reaches −43.8 kJmol−1 around 65 at. % Ni (CNi = 0.65). Such a strong chemical affinity between unlike species is also manifested by both the chemical short-range order and the medium-range order that the Ti-centered polyhedrons connecting with each other in Ni-rich melts. In addition, the self-diffusion coefficients of Ti and Ni atoms (DTi and DNi) both decline rapidly with increasing Ni concentration when CNi < 0.80, and these indice1441 and 1661 bonded-pairs are considered to be responsible for such evolution of dynamic properties. while a closely coupled behavior of DTi and DNi with an increasing trend in the composition of CNi > 0.80 is affected by both chemical short-range order and medium-range order.