Aluminum alloy mixed powder, and method and product for improving density of aluminum alloy product

Abstract

The invention belongs to the related technical field of laser additive manufacturing, and discloses aluminum alloy mixed powder, and a method and product for improving the density of an aluminum alloy product. The mixed powder comprises aluminum alloy powder and transition element carbide ceramic powder, wherein the aluminum alloy powder serves as matrix powder, and the mass fraction of the transition element carbide ceramic powder in the mixed powder does not exceed 10%. The mixed powder is used for laser additive manufacturing; when the mixed powder is molten by laser, the aluminum alloy powder and the transition element carbide ceramic powder are metallurgically bonded, and due to the difference of melting points, the aluminum alloy powder is molten while the transition element carbide ceramic powder is not molten; and thus, the transition element carbide ceramic powder forms similar pinning in the aluminum alloy powder, and strengthening of the aluminum alloy matrix powder is achieved. By means of the mixed powder, the mechanical property of the aluminum alloy product is improved, pores are reduced, and the density is improved.

Description

technical field [0001] The invention belongs to the related technical field of laser additive manufacturing, and more specifically relates to an aluminum alloy mixed powder and a method and product for improving the density of aluminum alloy products. Background technique [0002] Laser additive manufacturing is a process of rapid heating and rapid cooling. Due to the short scanning time of the laser beam, a large number of physical and chemical reactions occur, and the degree of supercooling is large. Alloying elements can quickly form a variety of compounds and increase the number of non-spontaneous crystal nuclei. , the maximum temperature, solidification speed, and supercooling degree of the liquid alloy in the molten pool affect the alloy solid solubility, crystal form, and phase type of the material, thereby affecting the performance of the material. Among them, the coaxial powder-feeding laser cladding additive manufacturing technology has high powder deposition effic...

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Problems solved by technology

[0003] Although the laser additive manufacturing technology has been greatly developed in recent years, due to the low absorption rate of the aluminum alloy to the laser, the material itself has high thermal conductivity, low density, easy oxidation and other physical characteristics determine its forming is extremely difficult. The energy input is easily transmitted and consumed along the substrate, resulting in a decrease in the temperature of the molten pool, an increase in the viscosity of the melt and a decrease in fluidity, making it difficult to effectively wet the matrix material, resulting in spheroidization effects and internal pores, cracks and other defects during the laser additive manufacturing process. These defects seriously hinder the development of this technology, so it is necessary to optimize the process to improve the density of laser additive manufacturing aluminum alloy

[0004] At present, there are mainly two types of published patents on improving the density of aluminum alloys manufactured by laser additive manufacturing. One is the method of removing pores in the laser cladding layer by optimizing the laser cladding device. The laser cladding device for pores / inclusions in the laser cladding layer reduces the pores and non-metallic inclusions in the laser cladding layer through the action of an alternating magnetic field, and improves the quality of the laser cladding layer; the second is to clad the aluminum alloy surface by laser The method of self-reaction to generate ceramic phase is representative of the proportional mixing powder WO disclosed in patent 201810520759.0 3 , graphite powder, SiO 2 ,TiO 2 It can self-react with the substrate to form a ceramic reinforcement phase, which can avoid the mechanical bonding between the traditional laser cladding layer and the surface of the metal substrate, inhibit the pores and cracks of the cladding layer, and enhance the wear resistance and corrosion resistance of the aluminum alloy surface; although these two methods can To a certain extent, aluminum alloy surface strengthening technology is carried out, but the first method has limited ability to reduce pores through the action of alternating magnetic field, while the second method has incomplete reaction and is easy to form intermediate phases. Excessively high reaction temperature is easy to make the matrix The aluminum grains are long and coarse, which will have an adverse effect on the performance of the composite material

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