Role of volume fraction of second phase particles, dislocation-twin and twin-twin interactions in the reduced tension-compression yield asymmetry

Highlights: • Basal poles tilt from the normal direction to rolling direction for both hot rolled TZA521 and TZA1021 alloy. • The volume fraction of Mg₂Sn phase contributes little to reduced tension-compression yield asymmetry. • Grain subdivision by $\left(10\bar{1}2\right)$ twins and dislocation-twin interactions reduce yield asymmetry of a slip dominated deformation. • Twin-twin interactions account for the reduced yield asymmetry of a twinning dominated deformation. In the present study, TZA521 alloy and TZA1021 alloy were designed and subjected to extrusion process as well as extrusion followed by rolling process to uncover the role of volume fraction of second phase particles (Mg₂Sn phase in this work), dislocation-twin and twin-twin interactions in the reduced tension-compression yield asymmetry. Our results show that yield asymmetry is only weakly dependent on the volume fraction of Mg₂Sn phase, owing to the presence of some coarse Mg₂Sn phases and relatively large inter-particle spacing. Grain subdivision by $\left(10\bar{1}2\right)$ twins and dislocation-twin interactions are found to reduce the tension-compression yield asymmetry of a slip predominant deformation, i.e. tension along the rolling direction in the extrusion followed by rolling condition, while twin-twin interactions mainly account for the reduced tension-compression yield asymmetry during compression along the rolling direction for both alloys in the rolling following extrusion condition. The relevant mechanisms are discussed.