An investigation of compressive deformation behaviour for AZ91 Mg alloy containing a small volume of liquid

Deformation behavior and formability of AZ91 magnesium alloy containing a small volume of liquid were investigated by compressive tests between 703 and 803 K and by forging tests between 753 and 803 K. Partial melting occurred initially at 743 K, however, the deformation mechanism changed at 773 K. Thus, the presence of liquid does not always lead to a change in deformation mechanism. The forging tests showed that excellent formability was attained at more than 773 K. It was suggested that the liquid serves to relax the stress concentrations caused by piles of dislocations, resulting in acceleration in flow of the solid. Also, grain refinement due to dynamic recrystallization was attained. Thus, both excellent formability and grain refinement were simultaneously attained by compressive deformation in a semi-solid state containing a small volume of liquid. (C) 2003 Acta Materialia Inc. Published by Elsevier Science Ltd. All rights reserved.