A method for improving the fluidity of tial-nb alloy in liquid state

Abstract

The invention discloses a method for improving liquid-state fluidity of a TiAl-Nb alloy. The TiAl-Nb alloy is Ti-(40-50)Al-(5-10)Nb by atomic percent, and the balance is Ti. The method comprises the following steps: a water-cooled copper crucible is adopted to electromagnetically induce a suspension-smelted TiAl-Nb master alloy ingot; firstly, niobium is put at the bottom of the copper crucible, titanium is put along the wall of the crucible, and aluminum is put in middle; the power is adjusted to 10 kw for keeping 20 S, and is adjusted to 15 kw until niobium, titanium and aluminum are totally molten and suspended; then, the power is adjusted to 20 kw for keeping 180 S, and the smelting is repeated by 4-5 times; the ingot is put in an arc furnace for gravity casting; after arc striking of the arc furnace, the current is adjusted to 150 A; after the surface of the master alloy ingot totally becomes a liquid state, the current is increased to 230 A, and the alloy totally becomes the liquid state; a tungsten electrode rod rotates from center to periphery; and when the current is increased to 320-350 A, the liquid level is descended to obtain a sample rod. The method can guarantee no burning loss of elements of the sample rod, is uniform in components, effectively improves the liquid-state fluidity of the TiAl-Nb alloy, and reduces such defects as shrinkage and porosity.

Description

technical field [0001] The invention belongs to the field of alloy technology, and in particular relates to a method for improving the liquid fluidity of TiAl-Nb alloy. Background technique [0002] After recent years of research on high-niobium TiAl intermetallic compounds, a series of important progress has been made in the research of phase diagram, oxidation resistance, structure and performance. Its excellent high-temperature performance has attracted widespread attention. The addition of high-content refractory metal niobium makes the melting point of the alloy increase by about 60-100°C compared with ordinary titanium-aluminum alloys. The solid-solution strengthening of niobium makes its 900°C yield strength It is 150-200MPa higher than ordinary titanium-aluminum alloy. The addition of high melting point niobium reduces the diffusion coefficient and improves the oxidation resistance. It is a new generation of high-temperature structural material with the most applicat...

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Problems solved by technology

The latter two smelting processes melt the electrode into metal droplets and solidify quickly after dropping into the water-cooled crucible. The temperature of the molten droplet is much higher than that of the induction melting melt, and the droplet is very small, so a single droplet The diffusion process is very sufficient, and there is basically no porosity and composition segregation in the solidification process, but the composition of each part of the consumable electrode cross section prepared by using pure components is different, so the composition of the droplet is different from the droplet , because a single droplet solidifies rapidly after being dropped into a water-cooled copper crucible, there is no composition homogenization process between the droplet and the droplet, and the high-melting point niobium has no time to diffuse and homogenize, resulting in severe segregation of niobium-aluminum in the alloy, which will lead to cast Severely uneven tissue

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