The use of the fracture initiation parameter F1 to predict microcrack nucleation at grain boundaries in Mg-2%Gd alloy

Highlights: • The fracture initiation parameter F1 was used to evaluate the probability of the grain boundary microcrack nucleation • Grain boundaries with larger F1 factor are more likely to cause microcrack nucleation • Extension twinning in the larger grain sized Mg-2%Gd alloy contributed to ductility improvement Intergranular deformation anisotropy and grain boundary (GB) microcrack nucleation were studied in Mg-2%Gd alloys by in-situ microscopy during tensile tests. A predictive fracture initiation parameter (fip) F1,which correlates with dislocation activity, twinning deformation and the geometrical orientation of GB, has been modified to evaluate the probability of the microcrack nucleation at GB. The statistical results revealed that the F1 factor which has been used to evaluate microcrack initiation in TiAl alloys can also well predict the nucleation of microcracks with this following law, i.e. GBs with larger F1 factor are more likely to cause microcrack nucleation.