Multiscale modelling of damage occurrence of eutectic phase in Al-Ni-Mn alloy

Aluminum-nickel binary alloys exhibit good thermal stability. However, by adding Mn microstructures of the alloy are largely changed and resulting mechanical properties could be significantly affected. A microstructure based approach coupled with damage criteria was proposed for investigating local stress, strain developments and damage mechanisms on the micro-scale of Al-4Ni-1Mn with Sc and Zr alloy. For the model, flow curves of each constituent phase were determined using both experiments and dislocation theory. Tensile test results of the alloy showed that damage mostly initiated within alpha-Al matrix and afterwards propagated to eutectic phase region. Therefore, the Hosford-Coulomb ductile damage model was employed for describing failure evolution of the Al matrix. The representative volume element (RVE) model fairly demonstrated microstructure deformation of a mini-tensile sample. Then, effects of different phase morphologies on local damage onset of the examined alloy were analyzed. It was found that eutectic particles with aspect ratio higher than 7 and oriented in parallel to loading direction were the most critical sites of cracking. This result was in accordance with experimental fracture analyses.