Abstract:The microstructures of Mg-Zn-Ce alloys, which were prepared by adding 0.6%, 1% and 2% Ce (mass fraction) based on an Mg-6Zn alloy, were refined by combining reciprocating extrusion and low-temperature forward extrusion. The phase composition and microstructural evolution in alloys were analyzed by X-ray diffractometry, optical microscopy, scanning electron microscopy and transmission electron microscopy, the mechanical properties were tested at room temperature. The results show that major intermetallics in Mg-6Zn-0.6Ce alloy is Mg₄Zn₇ phase, the major intermetallics in Mg-6Zn-1Ce and Mg-6Zn-2Ce alloy is T-(MgZn)₁₂Ce phase. The alloys are refined due to dynamic recrystallization after reciprocating extrusion, the grain size decreases with increasing Ce content, the grains sizes are 20.6 μm, 16.5 μm and 9.1 μm, respectively. The alloys are refined one more time due to dynamic recrystallization occurring once more during low-temperature forward extrusion, and the grain sizes are 2.0 μm, 8.6 μm and 1.9 μm, respectively. Mg-6Zn-0.6Ce alloys have the best mechanical properties, the yield strength, ultimate tensile strength and elongation are 266.4 MPa, 312.4 MPa and 12.8%, respectively. The excellent properties are attributed to the combination of fine grain strengthening, particle strengthening and solid solution strengthening.

Key words: Mg-Zn-Ce; magnesium alloy; reciprocating extrusion; extrusion; mechanical property