Effect Of High-pressure Torsion On Heat Treatment Of Quasicrystal Strengthened Magnesium Alloy

As the lightest metallic structural materials,magnesium and magnesium alloys are attracting more and more attention and has a a very good prospect.However,there have been only limited applications of Mg alloys in practice because of its disadvantages such as low intensity,poor corrosion resistance and so on.In this paper,Mg-11 wt%Zn-3 wt%Y alloy was processed by solution treatment,high-pressure torsion + solution treatment,solid solution + aging treatment,solid solution+ high pressure torsion + aging treatment respectively.X-ray diffraction?XRD?,scanning electron microscopy?SEM?,the optical microscope?OM?and other research methods were used to study the changes in the microstructure and structure of the alloy.Using tensile test and hardness test as alloy's comprehensive performance standards.The effect of high pressure torsion before heat treatment on subsequent heat treatment and the magnesium alloys was investigated.The results showed that after high pressure torsion,the secondary phases were broken and dispersively distributed within the magnesium matrix and existed distortion of crystal lattice;W-phase disappeared in the alloy after high pressure torsion and the precipitation of W-phase was repressed during the subsequent solution processing at a certain temperature.And the promotion effects of the high pressure torsion on the solution of the secondary phases can be found.The tensile strength of the samples processed by solid-solution treatment after high pressure torsion was higher than those without high pressure torsion.The tensile strength of as-cast Mg-11 wt%Zn-3 wt%Y alloy was 198.17 MPa.The best tensile strength of samples processed only by solid-solution was 235.54 MPa while the best tensile strength of samples processed by high pressure torsion before solid-solution was 270.58 MPa.The tensile strength has been greatly improved.The hardness of the solid solution sample after high pressure torsion is always higher than that of the solution treatment.The precipitation of Mg Zn₂ phase was promoted by high pressure torsion.Hardness of samples of high pressure torsion before aging treatment is always higher than that samples of only by aging treatment.So high pressure torsion play a major role in the increase of hardness,while the effect of subsequent age hardening was small.