Interaction between phase transformations and dislocation evolution: Nano- and microscale phase field approaches and experimental confirmations

Infos

Valery I. Levitas

The interaction between phase transformations (PTs) and dislocations determines transformational and elastoplastic material behavior in various technological processes, natural phenomena, and physical experiments. The following recent results on application of phase-field approaches (PFA) to modeling PTs, dislocation evolution, and their interaction will be discussed:

  • Nanoscale PFA for martensitic PTs that satisfy crystal lattice instability conditions under the action of all six components of the stress tensor obtained from the atomistic simulations. This includes new interpolation functions for transformation strain and elastic moduli. Introducing athermal interface resistance and interfacial stresses will be discussed. Multiphase PFA will be suggested with application to multivariant martensitic PTs and solid-solid PTs via intermediate melt at temperatures significantly below the thermodynamic melting temperature.
  • Nanoscale phase-field approach to dislocation evolution.
  • Nanoscale phase field approach to interaction between PTs and dislocations.
  • Scale-free PFA to martensitic PTs, which does not include gradient energy, where regularization of the problem is achieved through kinetic equations for the concentration of martensitic variants. Practical mesh independence of the solution is demonstrated in several examples.
  • Scale-free approach to evolution of discrete dislocation pileups, twins, and shear bands, which are described with the help of a contact problem in continuum mechanics.
  • Scale-free approach to the interaction between PTs and dislocations obtained as a combination of two previous approaches.
  • Large strain PFA for all the above processes.

Various problems on interaction between PTs and dislocations are solved using the finite element method and utilized to interpret experimental phenomena and results. The major application is the description of the drastic effect of plastic shear on the high-pressure PTs.  PFA to crack propagation and its interaction with PTs will be discussed if time allows.