CN1605642A - Method for preparing Al-Ti-B grain refiner - Google Patents

Abstract

The Al-Ti-B crystal grain fining agent for metal material has the components including Ti 2-10 wt%, B 2 wt% and Al the rest. The preparation process includes the steps of: mixing industrial pure potassium fluorotitanate and potassium fluoroborate homogeneously, heating to melt industrial pure aluminum, adding the mixed salt into aluminum melt and covering the surface of the melt with KCl, introducing ultrasonic wave to over the melt, skimming slag, cooling the melt naturally while continuous ultrasonic treatment until the intermediate alloy solidifies completely to obtain the Al-Ti-B crystal grain fining agent. The present invention has short preparation period and less oxidation loss of aluminum melt, and the obtained casting structure has fine TiAl3 grains of homogeneous size below 20 microns and TiB2 grains with clear contour. The Al-Ti-B crystal grain fining agent is used in preparing industrial pure aluminum with crystal grains smaller than 120 microns.

Description

The preparation method of Al-Ti-B grain-refining agent

Technical field

The present invention relates to a kind of preparation method of grain-refining agent of metal material field, specifically is a kind of preparation method of Al-Ti-B grain-refining agent.

Background technology

At present, in aluminium and alloy industry thereof are produced, generally adopt the method for in melt, adding the Al-Ti-B master alloy reaching the purpose of grain refining, and the villiaumite reaction method is generally adopted in the preparation of Al-Ti-B master alloy both at home and abroad.

Find through literature search prior art, the article " Grain refinement of aluminium and its alloy by heterogeneous nucleationand alloying (heterogeneous forming core of aluminium and alloy thereof and microalloying grain refining) " that B.S.Murty delivers at 2002 the 47th volumes of " International MaterialsReviews " (" international material comment ") magazine the 1st phase 3-29 page or leaf, the Al-Ti-B master alloy of mentioning in this article adopts the preparation of villiaumite reaction method, and the general technology of villiaumite reaction method is with K ₂TiF ₆(potassium fluotitanate) and KBF ₄(potassium fluoborate) mixing salt joins in the molten aluminium more than 750 ℃, it is reacted, thereby prepare the Al-Ti-B master alloy.Although the master alloy with this method preparation has certain thinning effect to commercial-purity aluminium and alloy thereof, the preparation cycle of master alloy is long, and energy consumption is big, and the oxidization burning loss of metal is serious; Intermetallic compound TiAl in the alloy structure ₃Particle is general thicker, size all more than 80 μ m, the time of response of having strengthened master alloy; The TiB that in organizing simultaneously refinement is played a crucial role ₂Particle is sticked together mostly and presents uneven gathering bulk distribution.After Al-Ti-B master alloy with this tissue morphology joins in the molten aluminium, thick TiAl ₃Phased soln increases adhesion TiB diffusion time ₂Particle accumulation group's bad dispersibility, thus make the detailed performance of master alloy not reach ideal effect, and the as-cast grain size after such master alloy refinement of commercial-purity aluminium process is generally all greater than 150 μ m.

Summary of the invention

The objective of the invention is to overcome the deficiency and the defective of existing above-mentioned technology, utilize the ultrasonic vibration technology, a kind of preparation method of Al-Ti-B grain-refining agent is provided, make it shorten the grain-refining agent preparation feedback time, reduce TiAl in the tissue ₃The size of phase is improved TiB ₂The distribution of particle, thereby the grain refining efficiency of raising Al-Ti-B master alloy.

The present invention is achieved by the following technical solutions, and method steps is as follows:

(1) according to generating weight percent be: 2-10%Ti, 0.5-2%B, the amount of all the other Al takes by weighing technical pure potassium fluotitanate (K ₂TiF ₆), potassium fluoborate (KBF ₄) and commercial-purity aluminium, and with technical pure K ₂TiF ₆And KBF ₄Uniform mixing;

(2), and be warming up to 750 ℃-900 ℃ with the commercial-purity aluminium fusing that is taken by weighing;

(3) utilize the stirring casting method with the K for preparing in (1) ₂TiF ₆And KBF ₄Mixing salt joins in the molten aluminium, and covers one deck 3mm left and right sides KCl at bath surface;

(4) be that 20 ± 1kHz, power are the ultrasonic wave of 100-5000W adding the molten aluminium top pull-in frequency of mixing villiaumite, supersound process continues 2-10 minute;

(5) skim after, make the melt naturally cooling, in the process of cooling, the ultrasonic wave that applies intensity described in (4) from melt top is continuously solidified fully until master alloy, obtains the Al-Ti-B grain-refining agent.

Innovation part of the present invention is to apply supersound process in the preparation of master alloy and process of setting.Because ultrasonic wave will produce acoustic cavitation and acoustic streaming effect when propagating in melt, preparing the Al-Ti-B master alloy with this method can shorten the prepared in reaction time greatly, reduces the oxidization burning loss of molten aluminium; And the TiAl in the master alloy as-cast structure ₃Be the fine particle shape mutually, size is below 20 μ m, and size evenly, and distribution situation is good; TiB in organizing simultaneously ₂The particle clear-cut, Individual existence each other, no longer adhesion, particle cluster presents loose fish-egg shape.

After Al-Ti-B master alloy of the present invention adds molten aluminium, TiAl ₃The dissolving and the diffusion time of phase are reduced TiB greatly ₂Dispersion of particles increases substantially, and helps the performance of its refining effect.Commercial-purity aluminium as-cast grain size through the refinement of the prepared Al-Ti-B master alloy of this method can be less than 120 μ m.

Embodiment

Further describe in conjunction with content of the present invention, and embodiment is provided, the preparation method is:

(1) according to generating weight percent be: 2-10%Ti, 0.5-2%B, the amount of all the other Al takes by weighing technical pure K ₂TiF ₆, KBF ₄And commercial-purity aluminium, and with two kinds of villiaumite uniform mixing;

(2) commercial-purity aluminium is melted in resistance furnace and be warming up to 750 ℃-900 ℃;

(3) utilize the stirring casting method with K ₂TiF ₆And KBF ₄Mixing salt adds in the molten aluminium, and covers the KCl of one deck 3mm at bath surface;

(4) be that 20 ± 1kHz, power are lasting the processing 2-10 minute of ultrasonic wave of 100-5000W from melt top pull-in frequency;

(5) melt is skimmed, fused mass after reaction is taken out from resistance furnace, naturally cooling, in the process of cooling, the ultrasonic wave that applies above-mentioned intensity from melt top is continuously solidified fully until alloy liquid.

Refinement: 500 gram commercial-purity aluminiums, heat fused to 720 ℃ adds prepared Al-Ti-B master alloy according to the amounts of 0.2 gram/100 gram aluminium, be incubated 15 minutes, pours into Reynolds standard golf T pattern, and measurement is apart from the grain-size at 51mm place, sample bottom surface.

The parameter and the implementation result of specific embodiment see the following form:

Embodiment	The master alloy composition	Molten aluminium intensification temperature (℃)	Ultrasonic power output (W)	The supersound process time length (min)	Ultrasonic frequency (kHz)	The postindustrial fine aluminium grain-size of refinement (μ m)
							????1	??Al-2Ti-0.5B	????750	????5000	????2	????20	????120
????2	??Al-5Ti-1.5B	????780	????2000	????5	????21	????105
							????3	??Al-5Ti-1B	????825	????1000	????6	????20	????95
????4	??Al-7Ti-1B	????850	????1000	????8	????21	????100
							????5	??Al-10Ti-2B	????900	????100	????10	????20	????110

Claims (5)

1, a kind of preparation method of Al-Ti-B grain-refining agent is characterized in that, concrete steps are as follows:

(1) according to generating weight percent be: 2-10%Ti, 0.5-2%B, the amount of all the other Al takes by weighing technical pure potassium fluotitanate K ₂TiF ₆, potassium fluoborate KBF ₄And commercial-purity aluminium, and with K ₂TiF ₆And KBF ₄Uniform mixing;

(2) commercial-purity aluminium that is taken by weighing is melted in intensification;

(3) utilize the stirring casting method with the K for preparing in (1) ₂TiF ₆And KBF ₄Mixing salt joins in the molten aluminium, and covers one deck KCl at bath surface;

(4) add mixing salt molten aluminium top introduce ultrasonic wave;

(5) skim after, make the melt naturally cooling, apply ultrasonic wave in the process of cooling continuously and solidify fully until master alloy, obtain the Al-Ti-B grain-refining agent.

2, the preparation method of Al-Ti-B grain-refining agent according to claim 1 is characterized in that, in the described step (2), commercial-purity aluminium is warming up to 750 ℃-900 ℃.

3, the preparation method of Al-Ti-B grain-refining agent according to claim 1 is characterized in that, in the described step (3), the KCl that bath surface covers is 3mm.

4, the preparation method of Al-Ti-B grain-refining agent according to claim 1 is characterized in that, in the described step (4), ultrasonic frequency is 20 ± 1kHz, and power is 100-5000W.

5, the preparation method of Al-Ti-B grain-refining agent according to claim 1 is characterized in that, in the described step (4), the supersound process time length is 2-10 minute.