Thermal Expansion of Ni ₃ Al Intermetallic Compound: Experiment and Simulation

Abstract

The thermal expansion of Ni3Al intermetallic compound is determined by a thermal dilatometer and simulated by the molecular dynamics method. The results of the linear thermal expansion coefficients are presented from 200 K up to the maximum temperature of 1600 K. The single phase of Ni3Al intermetallic compound is confirmed by x-ray diffraction together with DSC melting and solidification peaks, from which the solidus and the liquidus temperatures are obtained to be 1660 and 1695 K, respectively. The measured linear thermal expansion coefficient increases from 1.5 × 10 −5 to 2.7 × 10 −5 K −1 in the experimental temperature range, in good agreement with the data obtained by the molecular dynamics simulation, just a slight difference from the temperature dependence coefficient. Furthermore, the atomic structure and position are presented to reveal the atom distribution change during thermal expansion of Ni3Al compound.

First‐principles calculations of thermodynamic properties and planar fault energies in Co3X and Ni3X L12 compounds

“…Our results are in good agreement with the quasi harmonic phonon calculations . Between RT and 1000 K, the differences between our results and the experimental data are 0.19% and 0.47% , not very different from the difference between the experimental data themselves (0.26%). At 1400 K, the difference between our data (non‐SP) and the experimental data increases to 0.31%.…”

“…Between RT and 1000 K, the differences between our results and the experimental data are 0.19% and 0.47% , not very different from the difference between the experimental data themselves (0.26%). At 1400 K, the difference between our data (non‐SP) and the experimental data increases to 0.31%. This relative increase, in spite of its small magnitude, can be explained by the fact that at high temperatures, there is a dramatic increment due to anharmonicity which is not accounted for in Debye model.…”

“…This relative increase, in spite of its small magnitude, can be explained by the fact that at high temperatures, there is a dramatic increment due to anharmonicity which is not accounted for in Debye model. it is worth noting that at high temperatures our SP and non‐SP lattice parameters diverge, where the non‐SP data are closer to the available experimental data . We find the maximum increase (non‐SP) in the lattice parameter due to thermal expansion between RT and 1400 K to be 2% comparing to 1.88% experimental increase .…”

“…(a)), our SP ANNI results are in accordance with the SP quasiharmonic phonon supercell method values , while the SP ANNNI results greatly disagree. We have as well calculated the SISF at the experimental volumes , this technique has shown to produce values close to the experiment . Unfortunately, there is no experimental data to compare with.…”

“…Concerning Al, it is a weak itinerant ferromagnet with very low Curie temperature (= 41.5 K) and it retains an ordered structure until it melts (1660 K ). Our results are in good agreement with the quasi harmonic phonon calculations .…”