The small serrated flow, severe Portevin Le Chatelier phenomenon and abnormal strain-rate sensitivity were observed from the tensile curves of extruded Mg–5Li–3Al–1.5Zn–2RE alloy. The serrated curves were investigated by optical microscopy, step-tensile test and transmission electron microscopy. The small serrated flow was due to the traditional dynamic strain ageing. The positive strain-rate sensitivity was caused by dynamic strain ageing. The severe Portevin Le Chatelier phenomenon and the negative strain-rate sensitivity were attributed to a larger number of twins. Transmission electron microscope diffraction pattern revealed the {10•2} twin and {10•1} twins.

The Twin Mechanism of Portevin Le Chatelier in Mg–5Li–3Al–1.5Zn–2RE Alloy. T.Q.Li, Y.B.Liu, Z.Y.Cao, R.Z.Wu, M.L.Zhang, L.R.Cheng, D.M.Jiang: Journal of Alloys and Compounds, 2011, 509[28], 7607-10