Research

Processing materials to optimize microstructure so as to achieve desired performance standards is central to the materials-by-design paradigm. My research focuses on fundamental physics in two areas that underlie this approach: (1) phase transformation during materials processing, and (2) the defect-controlled mechanical properties of microstructures.  By deploying large-scale and parallel simulations at the atomic scale, I work to elucidate the thermally activated, non-equilibrium defect-driven processes that control these phenomena. For a full list of my publications, please see Google Scholar Profile or Researchgate.

I. Fundamentals of nucleation and crystallization processes

Nucleation is the controlling step for a wide range of phase transition processes.  It normally proceeds in very short time and length scales, under which conditions computer simulation methods provide a very powerful alternative to experimental methods.  Classical nucleation theory has been widely used for over 50 years, and few ground breaking improvement has been made.  Some of the interesting problems in nucleation theory are interface free energy calculation, nucleation path, and nucleation in non-uniform system.

  • Peng Yi, DH Ruan, TP Weihs, ML Falk, J. Phys. Chem., C. (2020) (link)
  • Peng Yi, ML Falk, TP Weihs, J. Appl. Phys. (2018) (link)
  • Peng Yi, ML Falk, TP Weihs, J. Chem. Phys. (2017) (link)
  • Peng Yi, GC Rutledge, Annual Review of Chemical and Biomolecular Engineering, 3, 157-182 (2012)

II. Crystal nucleation from polymer melts

The complexity of topological structure and length and time scales in polymer systems offer intriguing platform for processing glassy and semi-crystalline materials.

  • Peng Yi, C. Rebecca Locker, Gregory C. Rutledge, Macromolecules, 46, 4723-4733 (2013)
  • Peng Yi, Gregory C. Rutledge, Journal of Chemical Physics, 135, 024903 (2011)
  • Peng Yi, Gregory C. Rutledge, Journal of Chemical Physics, 131, 134902 (2009)

III. Binary alloys precipitation under deformation

It is well known that precipitation depends on thermal treatment conditions.  How the deformation affect the formation rate and morphology of precipitates are not well understood.  Fundamental understand of the elementary mechanism controlling deformation facilitated precipitate is important in multi-scale modeling and prediction of materials properties. 

  • Peng Yi, Michael L. Falk, “Dislocation assisted precipitate nucleation in Mg/Al alloys”, Physical Review Letter (submitted) 
  • S. Eswarappa Prameela, Peng Yi, B. Medeiros, V. Liu, L. J. Kecskes, M. L. Falk, T. P. Weihs, “Effect of Second Phase Particle Size on the Recrystallized Microstructure of Mg–Al Alloys Following ECAE Processing”, Magnesium Technology, pp167-173 (2020)
  • S. Eswarappa Prameela, Peng Yi, B. Medeiros, V. Liu, L. J. Kecskes, M. L. Falk, T. P. Weihs, “Deformation assisted nucleation of continuous nanoprecipitates in Mg-Al alloys”, Materialia, 9, 100583 (2020)
  • X. Ma, S. Eswarappa Prameela, Peng Yi, M. Fernandez, N. M. Krywopusk, L. J. Kecskes, T. Sano, M. L. Falk, T. P. Weihs, “Dynamic Precipitation and Recrystallization in Mg-9wt.%Al During Equal Channel Angular Extrusion: A Comparative Study to Conventional Ageing”, Acta Materialia, 172, 185-199 (2019)

IV. Dislocation- and twin- mediated crystal plasticity in magnesium alloys

Magnesium as a lightweight materials has drawn increasing interests for its applications in automobile, aerospace, and defense industries.  One of the challenge to its wide application is its low room temperature ductility, and low strength.  Alloying has shown potential to improve its room temperature ductility but the most effective alloying elements are rare earth elements, which are expensive.

  • Peng Yi, Scripta Materialia, (2020) (in revision)
  • Peng Yi, Michael L. Falk, Scripta Materialia, 162, 195-199 (2019)
  • Peng Yi, Robert C. Cammarata, Michael L. Falk, MSMSE, 25, 085001 (2017)
  • Peng Yi, Robert C. Cammarata, Michael L. Falk, Acta Materialia, 105, 378-389 (2016)

V. Mechanical properties in glassy materials

  • YZ He, P Yi, ML Falk, “Critical Analysis of an FeP Empirical Potential Employed to Study Fracture of Metallic Glasses”,Physics Review Letters, 122, 035501 (2019)