Elastic and thermodynamic properties of the Ni–B system studied by first-principles calculations and experimental measurements

The elastic and thermodynamic properties of NiB, Ni2B, Ni3B, orthorhombic Ni4B3(O–Ni4B3), monoclinic Ni4B3(M–Ni4B3), and Ni23B6, are calculated via first-principles method for the Ni–B system. The ground state energies, the full sets of elastic constants and the associated macroscopic elastic parameters of these Ni–B alloys are computed for the first time. Taking contributions from lattice vibrations and thermally excited electrons into account, thermodynamic properties at finite temperatures are then predicted. In addition, we measure the molar heat capacity at constant pressure for NiB and compare the results with the theoretical predictions. Various calculations demonstrate that the first-principles calculation can be used to clarify the diverse experimental data, and provide reliable thermodynamic data.