Shock Induced Order-disorder Transformation in Ni3Al

Abstract

The Hugoniot of Ni3Al with L12 structure is calculated with an equation of state (EOS) based on a cluster expansion and variation method from first principles. It is found that an order-disorder transition occurs at a shock pressure of 205GPa, corresponding to 3750K in temperature. On the other hand, an unexpected high melting temperature about 6955K is obtained at the same pressure, which is completely different from the case at ambient pressure where the melting point is slightly lower than the order-disorder transition temperature, implying the high pressure phase diagram has its own characteristics. The present work also demonstrates the configurational contribution is more important than electronic excitations in alloys and mineral crystals within a large range of temperature, and an EOS model based on CVM is necessary for high pressure metallurgy and theoretical Earth model.

14 pages, 5 figures

References in corpus (3)

• The Effect of Lattice Vibrations on Substitutional Alloy Thermodynamics
• Extension of the Wu-Jing equation of state (EOS) for highly porous materials: thermoelectron based theoretical model
• First-principles equation of state and phase stability for the Ni-Al system under high pressures

Cited by in corpus (7)

• First-principles study on oxidation effects in uranium oxides and high-pressure high-temperature behavior of point defects in uranium dioxide
• Cluster Expansion of Electronic Excitations: Application to fcc Ni-Al Alloys
• Hybrid expansions for local structural relaxations
• Order-disorder Effects on Equation of State in FCC Ni-Al Alloys
• Compression and phase diagram of lithium hydrides at elevated pressures and temperatures by first-principles calculations
• A computational study of the configurational and vibrational contributions to the thermodynamics of substitutional alloys: the Ni3Al case
• Theoretical assessment on the possibility of constraining point defect energetics by pseudo-phase transition pressures