Ab-initio Simulations of Molten Ni Alloys

Abstract

Convective instabilities responsible for misoriented grains in directionally solidified turbine airfoils are produced by variations in liquid-metal density with composition and temperature across the solidification zone. Here, fundamental properties of molten Ni-based alloys, required for modeling these instabilities, are calculated using ab-initio molecular dynamics simulations. Equations of state are derived from constant number-volume-temperature ensembles at 1830 and 1750 K for elemental, binary (Ni-X, X= Al, W, Re, and Ta) and ternary (Ni-Al-X, X= W, Re, and Ta) Ni alloys. Calculated molar volumes agree to within 0.6-1.8% of available measurements. Predictions are used to investigate the range of accuracy of a parameterization of molar volumes with composition and temperature based on measurements of binary alloys. Structural analysis reveals a pronounced tendency for icosahedral short-range order for Ni-W and Ni-Re alloys and the calculations provide estimates of diffusion rates and their dependence on compositions and temperature.

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Document Details

Document Type
Technical Report
Publication Date
Apr 01, 2010
Accession Number
ADA523968

Entities

People

  • Christopher Woodward
  • Dallas R. Trinkle
  • James Lill
  • Mark Asta
  • Stefano Angioletti-uberti

Organizations

  • Air Force Research Laboratory

Tags

Communities of Interest

  • Air Platforms
  • Ground and Sea Platforms

DTIC Thesaurus Topics

  • Accuracy
  • Air Force
  • Binary Alloys
  • Chemistry
  • Computational Science
  • Dynamics
  • Engineering
  • Equations
  • Equations Of State
  • Liquid Metals
  • Materials
  • Materials Engineering
  • Materials Science
  • Mathematical Models
  • Measurement
  • Molecular Dynamics
  • Simulations

Fields of Study

  • Materials science
  • Physics

Readers

  • Materials Science and Engineering.
  • Powder metallurgy of Titanium alloys.