Method for preparing directionally-crystallized rare-earth ultra-magnetostrictive alloys and directional crystallization device

Abstract

The invention discloses a method for preparing directionally-crystallized rare-earth ultra-magnetostrictive alloys by using a cooled crucible induction technology, comprising the following steps: applying a high-frequency electromagnetic field to rare earth and iron mixture raw materials in a water-cooled crucible in a vacuum chamber under a vacuum environment or an environment which is vacuumized and then filled with inert gas, so that the raw materials are melted to form a melt; then, continuously and slowly moving a crucible bottom of the water-cooled crucible downwards at a constant speed, wherein the crucible bottom is used as a crystallizer; enabling the melt (following the downward moving of the crucible bottom and then moving out of the lower end of the crucible wall) to enter a crystalline area, and carrying out axial directional crystallization on the melt along the longitudinal axial direction at a gradient distributed temperature, therefore, with the continuous downward moving of the crucible bottom, a solidified material rod is formed upwards from the surface of the crystallizer, wherein the solidified material bar is a directional crystallized alloy oriented along the moving direction of the crystallizer. The invention also provides a water-cooled crucible used in a directional crystallization technology and a cooled crucible directional crystallization device comprising the water-cooled crucible.

Description

technical field [0001] The invention relates to the field of preparation of directional crystallized alloys and crucible technology, in particular to a method for preparing directional crystallized rare earth giant magnetostrictive alloys using induction cold crucible technology, a water-cooled crucible used in directional crystallization technology and a A cold crucible directional crystallization device comprising the water-cooled crucible is provided. Background technique [0002] Rare earth giant magnetostrictive alloy is a kind of magnetostrictive material, Tb-Dy-Fe base alloy is the most important rare earth giant magnetostrictive alloy, and its optimal composition is Tb x Dy 1-x Fe 2-y The alloy (x=0.2-0.6, y=0-0.2), after forming a directional crystal structure oriented along the <112> direction, its magnetostrictive performance can be increased several times. [0003] Directional solidification is the most commonly used method to form a directional crystal ...

AI Technical Summary

Problems solved by technology

Second, rare earth giant magnetostrictive alloys are particularly sensitive to impurities and have strict requirements on the accuracy of the composition. Therefore, once the above-mentioned effects are caused by the crucible, the performance of the material will be greatly reduced

Third, the rare earth elements terbium and dysprosium in rare earth giant magnetostrictive alloys are particularly expensive, especially terbium, whose price is close to 10,000 yuan / kg. A few millimeters of the outer layer of the finished rod with a thickness of 30mm has become silicide, and 30-40% of precious elements will be lost after grinding this layer, which makes the price of the finished product very expensive and affects the application of the material.

Therefore, in the cold crucible technology, the method of moving the crucible down cannot be used for directional solidification

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