A new method to elucidate fracture mechanism and microstructure evolution in titanium during dissimilar friction stir welding of aluminum and titanium

In the friction stir welding (FSW) of dissimilar materials, weld nugget exhibits composite properties and is composed hard particles (high-strength material) distributed in a soft matrix material. The distribution these influences weld. Therefore, it useful to characterize deformation fragmentation high-strength material from which they originate. current study, FSW aluminum (Al) titanium (Ti) was performed new technique introduced remove Al post-weld sample Ti nugget. showed that were inhomogeneously distributed. It understood plastic depends on its location A detailed investigation revealed number fracture zones titanium. systematic analysis evolution twins thermos-mechanically affected zone (TMAZ), whereas no-twins recrystallized grains noticed flake consolidated X-ray computed tomography (XCT) flakes subjected bending. Furthermore, width not identical along their length broken at middle region into two parts. can be concluded Ti, interface as flakes, severe lower homologous temperature leads formation adiabatic shear bands (ASBs). local within ASBs much higher than general temperature, leading recrystallization interface. Moreover, are prone crack nucleation propagation; hence, with different morphology sizes zone. inhomogeneous due variation particle size complex mechanical mixing. varied across homogeneous mixing center flow finer particles. With this understanding mechanism during possible engineer developed composites and/or nuggets materials achieve required combination properties. Graphical abstract • FSW, containing method by dissolving WN used elucidate Ti. Evolution identified. Inhomogeneous bending noticed. Deformation correlated process condition ASB formation.