Coupling with mechanics

Elastic stresses in solid materials originate from lattice mismatches, thermal expansion differences, or externally applied mechanical loads, leading to long-range interactions that influence grain structure, phase stability, and domain morphology. By integrating micro-elasticity, phase-field models can accurately capture these stress-induced effects on microstructure evolution, as well as their impact on material properties and response to external loading.

Model development & testing

For numerical efficiency, the width of the diffuse interfaces in phase-field models must be increased artificially by several orders of magnitude when simulating on experimentally relevant length scales. An important challenge in phase-field models incorporating micro-elasticity, is developing formulations with scalable diffuse interface width that maintain an accurate description of mechanical equilibrium and material continuity at the interface.

Precipitate and intermetallic compound growth in mechanically loaded materials

Precipitation and phase transformations in solid materials are strongly affected by long-range elastic interactions due to lattice mismatch, particularly when interfaces are coherent or semi-coherent. The phase-field method coupled to micro-elasticity and local plasticity models is well suited to study these effects and predict, for example, precipitates shape and arrangement and variant selection.

Twin nucleation and growth and evolution of precipitates in Mg and Mg-RE- alloys

This work has been performed in collaboration with Hong Liu, Shanghai Jiao Tong University.

Twinning is a deformation mechanism in which a portion of a crystal lattice reorients, creating a mirrored structure across a defined twin boundary. This process enables deformation pathways in materials with limited slip systems, such as hexagonal close-packed (HCP) metals. Twinning plays a critical role in influencing mechanical properties, texture evolution, and strain accommodation in various materials, including magnesium alloys. A phase-field approach including micro-elasticity enables the study of nucleation and morphology of deformation twins in mechanically loaded materials.

Furhter reading

Magnesium-rare-earth (Mg-RE) alloys have been extensively studied due to their lightweight nature, excellent castability, and high strength. Many of these alloys exhibit significant precipitation hardening potential. The phase-field method, combined with micro-elasticity theory, provides valuable insights into the mechanisms governing precipitate formation and growth. This approach enables the optimization of heat treatment schedules for various Mg-RE alloys, enhancing their mechanical performance.

On the evolution of beta1/beta' coupled structures in Mg-Y-Nd alloys: A simulation study (2024)

Microstructure Simulation Lab Leuven