Strength-plasticity Synergistic Strengthening of LZ91 Magnesium Alloy Microtubules Induced by Severe Plastic Deformation
LZ91 magnesium alloy microtubules with an outer diameter of 2 mm and a wall thickness of 0.3 mm were prepared by raw material extrusion rod+final extrusion and equal-channel angular pressing(ECAP)rod+final extrusion,respectively.The microtubule microstructure and mechanical properties obtained in two ways were investigated.The results show that after adding ECAP,the yield strength,tensile strength and elongation of microtubules increase from 170,185 MPa and 22％to 200,210 MPa and 30％,respectively.This is mainly due to the fact that the microstructure is refined by ECAP and the MgO and ZnO existing in the original structure are converted into dispersed nano-sized particles.These nano-oxides promote the dynamic recrystallization of the matrix and improve the thermal stability of the microstructure during the subsequent extrusion process.Room-temperature tension can cause the dislocation motion resistance and the processing hardening rate increases,which simultaneously increases the strength and plasticity of the microtubules.
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