RheoMan: a five-year, ERC-funded (Advanced Grant), project to model the rheology of the Earth's mantle

Mar 2, 2017 Modeling MgO plasticity Results

For the first time, the mechanical properties of MgO can be derived from numerical modeling in the whole temperature range (from low temperature plasticity to High temperature creep) without any adjustable parameter


We applied the newly developed 2.5D dislocation dynamics modeling tool to MgO, in order to capture its deformation behavior under different temperatures. We first use the 2.5D-DD method to describe the plasticity of MgO in the low (T ≤600 K) and intermediate (T =1000 K) temperature regimes, where only dislocation glide is active. This allows to bench-mark our 2.5D approach against previous 3D-DD simulations and experimental data. This demonstrates that we are able to reproduce the key features of deformation in these two temperature regimes.

 

 


This allowed us to do a step further and introduce dislocation climb at high temperatures (1500≤ T ≤1800 K), where this mechanism has a relevant role on creep of MgO crystals. This was not feasible in previous 3D-DD formulations, due to the computational complexity of coupling phenomena occurring on very different time scales (such as dislocation glide and climb). Results in this regime mirror the available experimental data on high temperature power-law creep of MgO, providing the framework to investigate plasticity of this phase under lower mantle conditions.

 

 

 

R. Reali, F. Boioli, K. Gouriet, P. Carrez, B. Devincre & P. Cordier (2017) Modeling plasticity of MgO by 2.5D dislocation dynamics simulations. Material Science & Engeneering A, 690, 52-61, http://dx.doi.org/10.1016/j.msea.2017.02.092 . Open access.