Strengthening against {10(1)over-bar2} twinning by discontinuous and continuous precipitate in a strongly textured Mg-9Al alloy

Precipitate strengthening against {10 (1) over bar2} twinning was examined and compared with basal and prismatic slip in a strongly textured Mg-9Al extrusion plate. The plate was aged for various periods of time and mechanically tested in three orientations. The estimated critical resolved shear stresses (CRSS) for {10 (1) over bar2} twinning was increased by 54 MPa, significantly larger than the 18 MPa for basal and the 21 MPa for prismatic slip. Of the two types of precipitate responsible for the larger increment of CRSS for twinning, the discontinuous precipitate was suggested to have a stronger suppressing effect on the twin nucleation and propagation than the continuous precipitate.