mg-zn-cu-zr-(cr-ca) alloy under gpa level high pressure and its preparation method

Abstract

The present invention proposes a Mg‑Zn‑Cu‑Zr‑(Cr‑Ca) alloy and a preparation method under GPa level high pressure. A six-sided hydraulic press is used to prepare the Mg‑Zn‑Cu‑Zr‑(Cr,Ca) alloy at 2 GPa. Solidification was carried out under high pressure of ~6GPa, and the solidification structure characteristics, distribution patterns of solute elements such as Zn, Cu and Ca, heterogeneous crystal nuclei and strengthening and toughening mechanisms during high-pressure solidification were studied using EBSD, SEM and other analytical methods. The results show that the primary crystal α-Mg of the high-pressure solidification alloy is a regular equiaxed crystal, and the average grain size gradually refines from 186 μm under normal pressure to 22 μm under 6GPa; the solid solubility of Zn in the α-Mg matrix It gradually increases from 3.63% under normal pressure to 6.23% under 6GPa, and the intergranular second phase gradually changes from a network under normal pressure to an intermittently distributed island or granular shape under 6GPa; MgZn 2 ,Mg 2 Ca and Cr 2 The Zr phase is a strong and effective heterogeneous nucleation substrate for α-Mg crystals during high-pressure solidification, which greatly increases the number of crystal nuclei during the solidification process. The strength of the alloy increases as the solidification pressure increases, and the maximum resistance during compression increases from 240MPa under normal pressure to 520MPa under 6GPa.

Description

technical field [0001] The invention belongs to the technical field of Mg-Zn-Cu alloys, and relates to a Mg-Zn-Cu-Zr-(Cr-Ca) alloy under the action of GPa level high pressure and a preparation method. Background technique [0002] Mg-Zn-Cu alloy is a relatively successful Mg-Zn heat-resistant alloy in commercial application so far. Since Cu exists in the eutectic phase Mg(Zn,Cu) 2 Among them, it has better high temperature performance below 150°C, and can be used in automotive engine parts and propellers. However, the cast Mg-Zn-Cu alloys reported publicly have coarse as-cast structures, and the main strengthening phase Mg(Zn,Cu) 2 The eutectic phase is multi-linked into a network and distributed between dendrites, not only Mg(Zn,Cu) 2 The strengthening effect of the phase cannot be fully exerted, and the mechanical properties of the cast Mg-Zn-Cu alloy will also be reduced. Therefore, in order to further improve the mechanical properties of Mg-Zn-Cu alloy and expand its...

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Problems solved by technology

According to the existing high-pressure solidification theory, the pressure always reduces the activation energy of nucleation and increases the nucleation rate; inhibits the diffusion of atoms and increases the activation energy of atomic diffusion, thereby increasing the activation energy of crystal growth and reducing the crystal growth rate

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