Effect of cerium on the deformation behavior of two Mg-Ce alloys

The effect of cerium on the formability of Mg alloy tubes was investigated by means of uniaxial tension and uniaxial compression testing. The tests were carried out at ambient temperature and 200°C at strain rates of 0.1/s and 0.001/s. Samples were cut from two extruded Mg alloy tubes containing two different levels of Ce addition. Specimens deformed to increasing strain levels were examined by optical microscopy and electron backscattered diffraction (EBSD) techniques. At both test temperatures, higher tensile ductilities were observed in the Mg-0.5%Ce material than in the Mg-0.2Ce%, especially at the higher strain rate. However, at 200°C/0.001s-l, the Mg-0.2%Ce displayed better formability than the Mg-0.5Ce%, due to the occurrence of dynamic recrystallization in the Mg-0.2%Ce but not in the Mg-0.5%Ce. The better ductility of the Mg-0.5Ce% can be attributed to its fine grain size, uniform microstructure and initial texture which does not favor (10-11) contraction and {10-12}-(10-11) double twinning.