Fig. 1 Schematic illustration of FSW a illustration of sample preparation for tensile test b

Fig. 2 Cross-sectional morphologies of the FSW joint: a AM60/AZ31 joint; b AZ31/AM60 joint

Fig. 3 Inverse pole figures of various regions of the AM60/AZ31 joint

Fig. 4 Grain size distributions of the AM60/AZ31 joint a; force diagram of TMAZ during FSW b

Fig. 5 AZ31 metal a; AM60 metal b of the AZ31/AM60 joint

Fig. 6 Grain boundary maps, misorientation angle distributions and grain morphology maps of BMs: a AM60; b AZ31

Fig. 7 Grain boundary maps, misorientation angle distributions and grain morphology maps of TMAZs: a AS; b RS

Fig. 8 Grain boundary maps, misorientation angle distributions and grain morphology maps of NZ: a NZ side of AS; b NZ side of RS; c NZ center

Fig. 9 Schematics of the welding process: a schematic illustration of the FSW process in NZ; b schematic illustration of the shear layer formation induced by motion of the FSW tool

Fig. 10 Texture distributions in various regions of the AM60/AZ31 joint

Fig. 11 a Stress-strain curves ; b fracture morphology of the AM60/AZ31 joints

Fig. 12 Fracture morphologies of three types of tensile samples: a , d TD; b ,e 45°; c , f WD

Fig. 13 Dislocation density mapping based on the EBSD data in a AM60, b TMAZ of AS, c NZ side of AS, d AZ31, e TMAZ of RS, f NZ side of RS

Fig. 14 SFs distributions in various regions of the joint: (0001) pole figures show the calculated SF for basal slip

Fig. 15 SFs distributions in various regions of the joint: (0001) pole figures show the calculated SF for extension twinning

Fig. 16 Mean SF values in various regions for a basal slip ; b extension twinning

Fig. 17 EBSD maps of WD samples after fracture: a kernel average misorientation map; b grain boundary map

Fig. 18 OM and EBSD maps of a TD ;b 45° samples after fracture

Fig. 19 SEM images showing second phases: a AZ31 BM; b NZ; c AM60 BM

Fig. 20 a 45° samples before fracture, b OM ;c EBSD maps of joint bottom