Coupled elastoplasticity and plastic strain-induced phase transformation under high pressure and large strains: Formulation and application to BN sample compressed in a diamond anvil cell

摘要: Abstract In order to study high-pressure phase transformations (PTs), high static pressure is produced by compressing a thin sample within strength gasket in diamond anvil cell (DAC). However, since PT occurs during plastic flow, it classified and treated here as strain-induced PT. A thermodynamically consistent system of equations for combined flow PTs formulated large elastic, plastic, transformation strains. The Murnaghan elasticity law, pressure-dependent J2 plasticity (both dependent the concentration phase), kinetics are utilized. computational algorithm finite element method (FEM) presented implemented user material subroutine (UMAT) FEM code ABAQUS. Combined from highly-disordered hexagonal boron nitride (hBN) superhard wurtzitic wBN simulated rhenium pressures up 50 GPa. evolution fields stresses strains, well phases obtained discussed detail. Stress-strain well. An unexpected shape deformed with almost complete external part that penetrated was found. Obtained results demonstrated difference between behavior which often confused experimentalists. Thus, while may start (and end) at straining slightly above 6.7 GPa, not visible below 12 GPa. It becomes detectable 21 GPa completed everywhere even maximum Due strong gradient much smaller than strain, therefore distribution mostly determined strain field instead field. Possible misinterpretation experimental data characterization discussed. developed model will allow design experiments synthesis phases.