Extended Data Fig. 9. Finite temperature GB phase transformations under stress.

MD simulations of GB phase transformations and equilibrium coexistence at 500K under a, b ambient conditions c tensile stress and d shear stress. To avoid hysteresis due to nucleation barrier we start with a two phase state shown in a and monitor the direction of the GB phase junction migration. b, At ambient conditions pearl phase grows and the junctions moves to the left. c, Under tensile stress of 3.95 GPa domino becomes thermodynamically more stable, it grows at the expense of pearl and the junction moves to the right. d, Under shear stress of 342 MPa parallel to the GB plane in the direction parallel to the tilt axis domino phase also becomes more stable and grows. The back arrow indicates the initial position of the GB phase junction, while the green line shows the final position. We performed similar simulations at different tensile and shear stresses and conclude that in the model the equilibrium coexistence between pearl and domino phases at this temperature of 500K can be achieved around 3.3 GPa tension or 200-350 MPa interval of shear stress. The simulations of equilibrium coexistence confirm that pearl and domino are examples of GB phases. The MD simulations ran for 200 to 400 ns.