BSTRACTRecent molecular dynamics simulations for phase transformations (PTs) Si ISi II under multiaxial loading revealed that lattice instability criteria for Si ISi II PTs are linear in the stresses normal to the

cubic faces; instability stress depends on and is independent of shears; for some stresses

the instability stresses are the same for direct and reverse PTs; at critical stress

the first-order PTs are substituted with the second-order PT. We demonstrated that these features can be qualitatively reproduced using the simplest model with quadratic elastic energy in terms of Lagrangian strain.

IMPACT STATEMENT

Various nontrivial features of the martensitic transformation and lattice instability under complex loading in silicon are reproduced using the simplest model with quadratic elastic energy in terms of Lagrangian strain.