A heat-resistant flame-retardant magnesium alloy and its deformation heat treatment method

Abstract

The invention discloses a heat-resistant flame-retardant magnesium alloy and a thermo-mechanical treatment method thereof. The magnesium alloy comprises the following elements by mass: 3-16% of Gd, 4-8% of Er, 0.2-1% of Ca, 0.02-0.2% of Zn and the balance being Mg, wherein the mass ratio of Ca to Zn is >= 3. Magnesium alloy ingot billets are prepared by semi-continuous casting, and subjected to hot rolling or hot extrusion to form a plate being 5-25 mm in thickness, the plate is subjected to solid solution treatment, aging is performed at 200-260 DEG C, and water quenching is performed; and then, true strain is performed between room temperature and 100 DEG C, then aging is performed at 150-220 DEG C, and water quenching is performed. The alloy prepared in the invention contains a honeycomb microstructure consisting of a prismatic-plane precipitated phase, a prismatic-plane dislocation, a basal-plane precipitated phase and a basal-plane dislocation; the effect of the synchronous improvement on the heat-resistant and flame-retardant properties of the magnesium alloy is significant; simple equipment, low production cost and high efficiency are achieved; and the magnesium alloy is suitable for use in the industries of aeronautics and astronautics, railway trains and automobile lightweight.

Description

technical field [0001] The invention relates to a heat-resistant and flame-retardant magnesium alloy and a deformation heat treatment method thereof, in particular to a method of adding flame-retardant elements Gd, Er and Ca, and using low-temperature deformation heat treatment to introduce columnar precipitated phases and columnar surfaces into magnesium alloys. Dislocations, basal plane precipitates, and basal plane dislocations form a honeycomb internal microstructure, thereby preparing a magnesium alloy with high heat resistance and high flame retardancy, which belongs to the field of non-ferrous metal materials and processing technology. Background technique [0002] Magnesium alloy is the lightest metal structural material at present, and has broad application prospects in national defense, aerospace and automobile industries. However, there are still deficiencies in the safe application of magnesium alloys in replacing steel and aluminum. Among them, the heat resistanc...

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Problems solved by technology

[0002] Magnesium alloy is the lightest metal structural material at present, and has broad application prospects in national defense, aerospace and automobile industries. However, there are still deficiencies in the safe application of magnesium alloys in replacing steel and aluminum. Among them, the heat resistance strength is insufficient, Poor flame retardancy is one of the main problems

The addition of Ca element has been proven to improve the ignition point of magnesium alloys, but the solid solution limit of Ca in the magnesium matrix is ​​low, the improvement of the ignition point is limited, and the yield strength of magnesium alloys is damaged, resulting in a decrease in creep life.

At the same time, the magnesium alloys relying on rare earth elements for solid solution strengthening have a large amount of basal slip to start during the medium-high temperature creep process, resulting in large creep strain and fast creep rate; the magnesium alloys relying on rare earth elements for aging strengthening in creep In the process of creeping, it is easy to dissolve the precipitated phase and form no-precipitation zone, and the creep life is still relatively short.

It can be seen that in view of the problems of low ignition point and short creep life of magnesium alloys, it is urgent to propose a method for preparing magnesium alloys with high heat resistance and high flame retardancy.

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