Investigation of tension–compression asymmetry of magnesium by use of the acoustic emission technique

The acoustic emission (AE) technique has been applied to in situ investigations of deformation processes of polycrystalline magnesium with various grain sizes in tension and compression from 20 to 300 °C. The AE signal of twin nucleation exhibited an asymmetry corresponding to the tension–compression flow stress asymmetry due to easier { 1   0   1 ¯   2 } twinning in compression. A maximum in the AE signal is observed at 200 °C and is interpreted as a consequence of the synergetic effect of twinning and greater slip activity at higher temperatures. A larger grain size (600 μm) facilitated twinning.