This project belongs to the direction of non-ferrous metals and their alloy materials in the field of new materials.
With the urgent need for lightweight in the aerospace field, lightweight, high-strength and heat-resistant magnesium alloys have become a competitive hotspot and focus in the field of advanced material technology. However, the shortcomings of magnesium alloy materials such as small selection range, low strength, poor heat resistance, difficulty in purification, poor forming performance, and backward process and equipment have seriously hindered the lightweight process of aerospace equipment and the improvement of flight indicators. Supported by major national aerospace projects, major aviation projects, 973 Plan, 863 Plan and other projects, this project has achieved a series of creative results in the development of high-strength and heat-resistant magnesium alloy materials and their application technologies.
(1)This project systematically studied the strengthening and heat resistance mechanisms of rare earth elements (especially heavy rare earth elements) in magnesium alloys, studied the microstructure and fine structure of Mg-Gd-Y magnesium rare earth alloys, clarified the composite strengthening and strengthening theory of rare earth magnesium alloys, and determined the aging precipitation sequence of Mg-Gd-Y magnesium alloys. Invented the internationally leading high-strength and heat-resistant Mg-Gd-Y series new magnesium rare earth alloy JDM2. The cast T6 state room temperature tensile strength is>400MPa, yield strength is>350MPa, and elongation is>5%;300 ° C high temperature tensile strength is>265MPa, yield strength is>210MPa, elongation is>29%; extruded T5 state room temperature tensile strength is>490MPa, yield strength is>380MPa, elongation is>10%; The tensile strength at 300℃ at high temperature is>300MPa, the yield strength is>230MPa, and the elongation is>30%. The problems of low strength and poor heat resistance of magnesium alloys have been overcome.
(2)In view of the characteristics of magnesium alloys that are easy to oxidize and burn, difficult to remove inclusions, and difficult to control the composition of rare earth elements, a model for accelerating the transfer of inclusions in magnesium melts is proposed, and the dynamic loss mechanism of rare earth elements in magnesium melts is revealed. A composite purification system integrating high-strength and heat-resistant Mg-Gd-Y magnesium alloy refining flux, iron removal flux, magnesium melt purification device, and magnesium alloy melt protection device is invented, realizing efficient removal of oxidation inclusions in magnesium liquid and control of burning loss rate of rare earth elements. It solves the worldwide problem of purifying magnesium rare earth alloys.
(3)In terms of refining and solidification structure control, a method for preparing magnesium, gadolinium and yttrium ternary master alloy and a zirconium composite cake refiner for smelting magnesium alloys were invented, and a method for combining current and Zr to compound refine the solidification structure of magnesium alloys was proposed. A method and device for online composition detection and solidification structure control of magnesium alloys were developed, which effectively controlled the pre-crystallization structure and structure of magnesium alloy melt, and realized the refinement and homogenization of as-cast structure.
(4)Magnesium alloy metal mold casting coatings were invented, resin self-hardening sand and flame retardant for magnesium alloy sand mold casting were developed, sealing materials and casting riser pipe coatings for magnesium alloy low-pressure casting crucibles were invented, and magnesium alloy coating transfer sand molds were developed. The precision low-pressure casting process has overcome the problem of easy oxidation and combustion during magnesium alloy casting filling process, and has broken through the bottleneck of low size accuracy and poor surface quality of large and complex magnesium alloy castings.
A total of 11 invention patents have been authorized, forming a technology group with independent intellectual property rights in application technologies such as high-strength and heat-resistant rare earth magnesium alloy materials, magnesium melt purification and grain refinement, magnesium alloy precision forming technology, and process equipment. Published more than 20 high-level academic papers and cited 677 times.
For the first time, this project has realized the manufacture of large-scale complex high-strength heat-resistant magnesium alloy components. The research results of the project have been applied in many major national projects such as Aerospace Group, Aviation Group, and National Defense Military Industry. The performance indicators all exceed the original design requirements and are highly praised by users. Evaluation has great social benefits. Relevant research results have been extended to automobiles and other civilian fields. In the past three years, the new output value has been 133.16 million yuan, the new profit has been 26.33 million yuan, the new tax revenue has been 13.29 million yuan, and the total new expenditure savings have been 14.73 million yuan. It has promoted the development of my country's advantageous resource magnesium and rare earth industries.