Method for preparing aluminum-scandium intermediate alloy by thermally reducing aluminum in elpasolite fused salt

Abstract

The invention discloses a method for preparing an aluminum-scandium intermediate alloy by thermally reducing aluminum in elpasolite fused salt and belongs to the technical field of materials. The method comprises the following steps: (1) mixing anhydrous KF and anhydrous AlF3; (2) adding Sc2O3 and uniformly mixing; (3) increasing the temperature of mixed salt to 720-1020 DEG C, and maintaining temperature for 30-60 minutes; and (4) adding reducer metal aluminum, thermally reducing at the temperature of 720-1020 DEG C, separating an alloy part and an electrolyte part, condensing the alloy part and then forming the aluminum-scandium intermediate alloy. An electrolyte system adopted by the method is high in solubility of KF-AlF3; the content of Sc in the prepared Al-Sc intermediate alloy meets the requirement of the national standard; low-cost scandium oxide is used as the raw material; the process is simple; the preparation process of the aluminum-scandium intermediate alloy is shortened; the production cost is reduced.

Description

technical field [0001] The invention belongs to the technical field of materials, and in particular relates to a method for preparing an aluminum-scandium master alloy by aluminothermic reduction in potassium cryolite molten salt. Background technique [0002] Sc is the most effective alloying element found so far. The addition of trace elements of Sc can significantly improve the mechanical properties, high temperature performance, corrosion resistance, welding performance and enhance the neutron radiation damage resistance of the alloy. It has broad application prospects in aerospace, nuclear reactors and transportation. Since the melting point of metal scandium is as high as 1541°C and its chemical properties are active, scandium must be added in the form of master alloy when preparing aluminum scandium alloy, so Al-Sc master alloy becomes the key raw material for preparing aluminum scandium alloy. [0003] At present, the preparation methods of Al-Sc master alloy at hom...

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Problems solved by technology

[0004] The blending method is to directly fuse metal aluminum and scandium at high temperature to prepare aluminum-scandium master alloy; in the preparation process of Al-Sc master alloy, aluminum and scandium are melted at high temperature, and a uniform aluminum-scandium alloy is formed after sufficient stirring, and the heat preservation is sufficient After a period of time, cast it into a preheated iron mold or copper mold; when using this method to prepare Al-Sc master alloy, due to the large difference in melting point between aluminum and scandium, aluminum and scandium are not easy to mix uniformly, and the segregation in the formed alloy is serious ; In addition, when adopting the method for preparing the Al-Sc master alloy, it is necessary to use pure metal scandium as a raw material, and the burning loss of scandium in the preparation process is relatively large, and the cost of the prepared alloy is relatively high

[0005] Molten salt electrolysis is usually referred to as Sc 2 o 3 As raw materials, it can be roughly divided into three categories according to the composition of the electrolyte, one is containing ScCl 3 or ScF 3 or ScCl 3 -ScF 3 Electrolyte system, Sc 2 o 3 The solubility in the electrolyte is high. When this electrolyte system is used for electrolysis, an Al-Sc master alloy with a Sc content of 2-6% can be electrolyzed, but ScCl 3 and ScF 3 The preparation process is based on Sc 2 o 3 As raw material, increase production cost, in addition ScCl 3 Hygroscopic and deliquescent, anhydrous ScCl 3 There are difficulties in the preparation and preservation of the nNaF-AlF and are not suitable for production applications; the second type is nNaF-AlF 3 Electrolyte system, Sc 2 o 3 in nNaF-AlF 3 The solubility in the electrolyte system is low, in addition, due to the Al 3+ The precipitation potential ratio of Sc 3+ Positive, Al in molten salt during electrolysis 3+ Priority discharge, the Al-Sc master alloy prepared in this electrolyte system contains less than 1% Sc, which cannot meet the requirement of 2% Sc content in the Al-Sc master alloy required by the national standard; the third type is KF-AlF 3 Electrolyte system. In this molten salt system, the aluminum-scandium master alloy containing 2% Sc cannot be obtained by electrolysis. After adding NaF to the electrolyte system, it can be prepared by electrolysis Aluminum scandium master alloy

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