Preparation Mechanism of Fine-Grained Magnesium Alloys by Accumulative Alternating Back Extrusion

Fine grain modification is an important means for preparing lightweight and low-plasticity materials, including magnesium alloys. This paper proposes an accumulative alternating back extrusion (AABE) technique for preparing magnesium alloy materials. Metallographic microscopy and electron backscatter diffraction were used to test the resulting magnesium alloy samples and indicated that AABE can effectively refine microstructure and improve uniformity in local areas of the sample. After one pass of AABE, the upper part of the specimen was mainly characterized by recrystallization, with a high degree of refinement. The lower part showed coexisting recrystallization refinement and twinning refinement, which are less preferable. The mean grain size after applying five passes of AABE was half that of the samples subjected to only one pass. AABE is a novel and effective method for preparing high-performance magnesium alloy materials.