Simple stress criterion for navigating phase transformations

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Scientific Achievement

Lattice instability criterion is linear in stresses for any stress state in a material.

Significance and Impact

Reveals new processing routes in solid-solid phase transformations. Enables navigating phase transformation to access novel states or high-pressure phases at lower stresses and pressures.

Research Details

  • High-throughput calculations were performed to sample a multidimensional space of deformations in materials with varied stress states.
  • Properties were computed versus complex stress and strain states; and lattice instabilities were found.
  • Instability criterion was analyzed using tensor algebra: Linearity vs. stress component was identified.
  • Competition of instabilities serves for phase selection, not free-energy minima in usual processing.

Nikolai A. Zarkevich, H. Chen, V.I. Levitas, and Duane D. Johnson, Phys. Rev. Lett. 121, 165701 (2018). DOI: 10.1103/PhysRevLett.121.165701