New Technology Transforms Rare Earth Magnesium Alloy

Recently, the Baotou Research Institute of Rare Earths has developed rare earth magnesium alloy grain refiner products with a zirconium particle size of less than 600 nm, filling a gap in product corresponding to high efficiency and low-cost magnesium alloy grain refiner.

"This provides a possibility to develop high-strength cast/deformed magnesium alloy materials for rail transportation equipment such as aircraft seats, automotive safety components, and lightweight high-speed trains," said Wenxin Hu, senior engineer and senior engineer of the Baotou Research Institute of Rare Earths' magnesium alloy project team.

At present, magnesium-zirconium master alloys are widely used as grain refiners in the domestic industrial field. Existing products on the market have low refinement efficiency of zirconium (less than 40%), large deposits of zirconium particles, high cost of refiners, and high impurity content. As well as many problems such as the instability of fine-grained process operation, bring a lot of difficulties to practical industrial applications.

"Magnesium alloy grain size control technology is one of the most fundamental and significant technical methods for regulating the properties of magnesium alloy materials. Zirconium and rare earth elements are effective refinement elements of magnesium alloys." Wenxin Hu said.

Based on previous research results on the coupling and refinement mechanism of rare earth and zirconium to magnesium alloys, Baotou Research Institute of Rare Earths supplemented it with a new metallurgical process preparation method to allow more densely distributed and smaller zirconium particles to provide more magnesium crystal nuclei. At the same time, the rare earth element enhances the ability of the magnesium crystal nuclei to adhere to the surface of the zirconium particles during the crystallization process, which can achieve the efficient refinement of the magnesium alloy grains.

Per the statistics, size of the refined particles is 30% of the size of the zirconium particles in the traditional magnesium-zirconium master alloy, the size distribution rate of the nano-sized particles is greater than 60%, agglomeration phenomenon between the particles is less than 5%, and the size of alloy grains in the as-cast state is reduced by 20% to less than 35 mm, showing a significant grain refining effect.

Wenxin Hu said: "This technology is of great significance to the industrialization of rare earth magnesium alloy ingot products. It can effectively reduce the non-uniformity of metal particles inside and outside the product, keep the size of the internal and external alloy particles basically the same, and greatly increase the stress level of the alloy."

With the rapid development of new energy vehicles and domestic 5G communications, there is a strong market demand for alloy materials that are lighter, which own better heat dissipation performance and excellent corrosion resistance, but the requirements for the corresponding performance of the rare earth magnesium alloy are becoming more demanding. There is a promising future for light- weight rare earth magnesium materials.

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