Understanding Strain Localization in Magnesium Alloy AZ31 and ZEK100 Through High-Resolution Digital Image Correlation (HRDIC) and Simulation

High-resolution digital image correlation (HRDIC) has been used to compare strain localization in conventional AZ31 and dilute rare-earth containing commercial ZEK100 magnesium alloys. The materials were processed to obtain a similar grain structure but have a different texture. It is demonstrated that whilst both alloys show strong concentration of strain in grain boundary regions, this is much more intense in AZ31 than ZEK100. Basal slip is observed to dominate in both AZ31 and ZEK100, although non-basal modes are also more active in the later case. Crystal plasticity simulations have been used to help explain the results. The predictions suggest that the higher local strains observed in AZ31 compared to ZEK100 can be reproduced through the texture difference between the materials alone, at least at the low plastic strains studied here. Other differences between the alloys, such as the ease of activating non-basal slip or grain boundary segregation, are expected but are therefore not essential to produce the difference in strain localization behaviour. These results are consistent with the hypothesis that the improved formability of ZEK100 compared to AZ31 is predominantly a texture effect.