CN1563455A

CN1563455A - Method for fabricating aluminum based composite material through composite reinforcement by in situ titanium diboride and dialuminum dioxide

Info

Publication number: CN1563455A
Application number: CN 200410031169
Authority: CN
Inventors: 杨滨; 张济山
Original assignee: University of Science and Technology Beijing USTB
Current assignee: University of Science and Technology Beijing USTB
Priority date: 2004-04-14
Filing date: 2004-04-14
Publication date: 2005-01-12
Anticipated expiration: 2024-04-14
Also published as: CN100554463C

Abstract

This invention provides a method for preparing situ TiB2 particle and Al2O3 whisker composite strengthened Al-base composite material characterizing that the process includes two steps of preparing prefabricated blocks and smelting Al-base composite material, the first step can select the three kinds of reaction substances, such as: Al+2Ti_4B+3O2->2Al2O3 +2TiB2, 4Al+2B+2O2+TiO2->2Al2O3+TiB2,8Al+3Ti+2B+3O2+2B2O3->4Al2O3+3TiB2, the raw materials are mixed uniformly in a mixing machine in chemical proportion to be pressed to formation under room temperature. A matrix alloy Al and its alloy are put into a MF induction furnace, heated, thermal insulated, refined and deaerated to formation.

Description

Preparation method of in-situ titanium diboride and aluminum oxide composite reinforced aluminum-based composite material

Technical Field

The invention belongs to the field of metal matrix composite materials, and particularly provides an in-situ TiB₂Particles and Al₂O₃The preparation method of whisker composite reinforced aluminum-based composite material can melt matrix alloy and enhance phaseThe generation is carried out synchronously, the preparation process flow of the composite material is obviously shortened, the manufacturing cost of the metal-based composite material is reduced, and the method can be widely applied to occasions requiring light high-strength composite materials.

Background

The development of modern science and technology has increasingly raised requirements on materials, and the materials are expected to have certain special properties and excellent comprehensive properties, so that the common single material is increasingly difficult to meet the requirements. The composite material has the advantages of exerting the synergistic effect of the raw materials, integrating the advantages of various materials, and having great freedom of material design, thereby showing strong vitality and being rapidly developed in the past decades.

According to the principle of material design, the reinforcing phase particles and the reinforcing and toughening whiskers which are dispersed and distributed are introduced into the matrix at the same time, so that the strength, the wear resistance and the creep resistance of the composite material can be improved at the same time. Songchuntai et al (self-reinforced SiC)_w/Si₃N₄Preparation and performance studies of composite materials, proceedings for silicates, 1993, 1: 1-8) investigating SiC_w/Si₃N₄Composite material, 15 vol% SiC obtained_w/Si₃N₄The composite material has excellent mechanical property, a steep peak and the like (crystal characteristics and internal defects of β -SiC crystal whisker prepared by a carbothermic method, silicate report, 1993, 2: 33-36) synthesizes β -SiC crystal whisker by using ultrafine carbon powder to thermally reduce kaolin, and the result shows that the synthesis temperature has obvious influence on the crystal morphology of the crystal whisker₂O₃The crystal whisker has excellent comprehensive performance, melting point of 2040 deg.c and density of 3.96 x 10³kg/m³Tensile Strength (σ)_b) Is 21X 10³MPa，σ_bA/[ rho]of 53X 10⁴m, elastic modulusThe amount (E) is 4.3X 10⁵MPa, E/rho of 11 x 10⁵m。TiB₂The alloy has high melting point, hardness and modulus, and good corrosion resistance, and is increasingly widely applied as a reinforcing phase in metal matrix composite materials. The applicant's research shows (Effect of Ti/catalysis on the formation of Al₃Ti of in situ TiC/Al composites，Materials&Design，2001，22(8)：645-650；Effect of Ti/B Additions on the Foration of Al₃Ti of insitu TiB₂Al Composites, Journal of University of Science and Technology Beijing, 1999, 4: 285-₂The performance of the particle reinforced aluminum matrix composite material is superior to that of the TiC particle reinforced aluminum matrix composite material. In the invention, an in-situ TiB is provided₂Particles and Al₂O₃The preparation method of the whisker composite reinforced aluminum-based composite material can be widely applied to occasions requiring light-weight high-strength composite materials.

Disclosure of Invention

The invention aims to: providing an in-situ TiB₂Particles and Al₂O₃The preparation method of the whisker composite reinforced aluminum-based composite material is used in occasions requiring light high-strength composite materials.

The invention is composed of: fusion casting-in-situ reaction TiB₂Particles and Al₂O₃The preparation method of the whisker composite reinforced aluminum-based composite material is characterized by comprising the following steps of: the process comprises two stages of preparing a precast block and melting an aluminum-based composite material:

a. preparing a precast block: al produced by fusion casting-in-situ reaction method₂O₃Whiskers in which the oxygen originates mainly from: oxygen in the air, impurity oxygen brought by the in-situ reactant, oxygen adsorbed on the surface of the powder, oxygen adsorbed on the surface of the precast block and oxygen brought by the in-situ reactant. In order to increase Al in the composite material₂O₃The amount of whiskers is necessary to further increase the oxygen content of the preform. To this end, three classes of reactants may be selected (of course, of the second class of reactantsB may also be added₂O₃TiO can also be added into the third reactant₂)：

The first type: ；

the second type: ；

in the third category: 。

ti, B, TiO mentioned in the above first, second and third categories₂And B₂O₃The powder is powder, the particle size range is 10-250 mu m, and the purity is more than 96.0 weight percent.

When the first type of reactants are combined, the ratio (weight ratio) of Ti to B is 1.5-2.8: 1; when combined as a second type of reactant, TiO₂The proportion range (weight ratio) of B and B is 2.8-4.2: 1; when combined as a third type of reactant, Ti, B and B₂O₃The ratio (weight ratio) of the components is 1: 5.5-7: 1.

Putting the raw materials into a mixer according to a stoichiometric ratio, uniformly mixing, and then pressing and forming the uniformly mixed raw materials at room temperature, wherein the pressure range is 25-100 MPa;

b. melting the composite material: putting 70-99.9% of matrix alloy Al and alloy thereof into a medium-frequency induction furnace for heating, wherein the heating temperature is 150-250 ℃ above the melting point of the alloy; then, the prefabricated block accounting for 1-10 wt% of the alloy is put into a furnacePressing into an alloy melt, and preserving heat: 1-30 minutes. Refining, degassing and forming, wherein the forming mode is pouring metal mold and sand mold or forming by using extrusion and die casting methods to obtain in-situ reaction TiB₂Particles and Al₂O₃The whisker is compounded and strengthened with the aluminum-based composite material.

In situ reaction TiB₂Particles and Al₂O₃The principle of the whisker composite reinforced aluminum-based composite material preparation technology is as follows: according to the requirements of material design, proper reactants are selected, and at proper temperature, by means of the chemical reaction between the base metal or alloy and the base metal or alloy, the in-situ generated material has fine size and uniform distributionThe reinforcing phase of (1). Compared with the traditional composite technology of the metal matrix composite material, the technology has the advantages that: (1) the reinforced phase is generated in situ in the matrix, and the surface is free of pollution; (2) the number of the enhancement phases can be adjusted within a certain range; (3) the strength and the elastic modulus of the composite material can be greatly improved while the higher toughness of the composite material is kept.

The invention has the advantages that: (1) TiB₂Particles and Al₂O₃The crystal whisker is generated by in-situ reaction in the melt, the utilization rate of the reinforced phase is high, and the crystal whisker and the particles are distributed more uniformly in the alloy matrix. (2) Simple process, low cost and easy realization of industrialization.

Drawings

FIG. 1 is an X-ray diffraction pattern of a Ti-B-Al reaction block in the present invention. As can be seen, the reaction mass is represented by TiB₂、Al₂O₃And Al. The scanning electron microscope tissue observation and the energy spectrum analysis confirm the generated Al₂O₃Whiskers rather than particles.

FIG. 2 is an in situ TiB of the present invention₂Particles and Al₂O₃And scanning the structure of the whisker composite reinforced aluminum-based composite material.

Detailed Description

Example 1

Preparation of Al₂O₃Whiskers (indeterminate weight%, the same applies hereinafter) and 3 wt% TiB₂Industrial pure aluminum composite material. Al powder, Ti powder and B powder with purity of 98%, 96% and 99% and particle size of 75 μm, 45 μm and 1 μm respectively are weighed according to the proportion of Al, Ti and B of 50: 35: 15 (weight percent) and mixed uniformly. Pressing into cylindrical prefabricated blocks with the diameter of 20X 30mm on a 50-ton press. 2 kg of industrial pure aluminum is melted in a medium frequency induction furnace and heated to 850 ℃. And pressing 0.12 kg of prefabricated blocks into the aluminum liquid by using a graphite bell jar, and keeping the temperature for 10 minutes. When the temperature is reduced to 750 ℃, hexachloroethane accounting for 0.4 weight percent of the molten liquid is added for refining. When the temperature of the melt is 720 ℃, pouring the melt into a metal moldTo obtain Al₂O₃Whiskers and 3 wt% TiB₂Industrial pure aluminum composite material. Composite material sigma_b168MPa and an elongation delta of 13%.

Example 2

Preparation of Al₂O₃Whiskers and 5% by weight of TiB₂The Al-21Si-2.5Cu composite material. In the ratio of Al to TiO₂Weighing appropriate amount of Al powder and TiO powder with purity of 98%, 96% and 99% and particle size of 75 μm, 75 μm and 1 μm respectively at a ratio of B to B of 50: 40: 10 (weight%)₂Mixing the powder with the powder B, and mixing uniformly. Pressing into cylindrical prefabricated blocks with the diameter of 20X 30mm on a 50-ton press. 4 kg of Al-21Si-2.5Cu alloy is put into a medium frequency induction furnace to be melted and heated to 950 ℃. And pressing 0.40 kg of prefabricated blocks into the aluminum liquid by using a graphite bell jar, and keeping the temperature for 15 minutes. When the temperature is reduced to 740 ℃, hexachloroethane accounting for 0.4 percent of the weight of the molten liquid is added for refining. Pouring into a metal mold when the temperature of the melt is 730 ℃ to obtain Al₂O₃Whiskers and 5 wt% TiB₂The Al-21Si-2.5Cu composite material. Composite material sigma_bIs 420 MPa.

Example 3

Preparation of Al₂O₃Whiskers and 5% by weight of TiB₂The/7075 composite material. According to the ratio of Al to Ti to B₂O₃Weighing appropriate amount of Al powder and TiO powder with purity of 98%, 96% and 99% and particle size of 75 μm, 45 μm and 1 μm at 35: 30: 5: 30 (wt.%), respectively₂Mixing the powder, Ti powder and B powder. Pressing into cylindrical prefabricated blocks with the diameter of 20X 30mm on a 50-ton press. 4 kg of 7075 aluminum alloy is melted in a medium frequency induction furnace and heated to 900 ℃. And pressing 0.50 kg of prefabricated block into the aluminum liquid by using a graphite bell jar, and keeping the temperature for 10 minutes. Adding hexachloroethane accounting for 0.3 percent of the weight of the molten liquid for refining. Pouring into a metal mold when the temperature of the melt is 730 ℃ to obtain Al₂O₃Whiskers and 5 wt% TiB₂The/7075 composite material. Composite material sigma after extrusion_b685 MPa.

Claims

1. Fusion casting-in-situ reaction TiB₂Particles and Al₂O₃The preparation method of the whisker composite reinforced aluminum-based composite material is characterized by comprising the following steps of: the process comprises two stages of preparing a precast block and melting an aluminum-based composite material:

a. preparing a precast block: three classes of reactants can be selected:

the first type:

the second type:

in the third category:

ti, B, TiO mentioned in the above first, second and third categories₂And B₂O₃The powder is powder, the particle size range is 10-250 mu m, and the purity is more than 96.0 weight percent;

when the first type of reactants are combined, the weight ratio of the Ti to the B is 1.5-2.8: 1; when combined as a second type of reactant, TiO₂The weight ratio of the B to the B is 2.8-4.2: 1; when combined as a third type of reactant, Ti, B and B₂O₃The weight ratio of the components is 1: 5.5-7.5: 1;

b. melting the composite material: putting 70-99.9% of matrix alloy Al and alloy thereof into a medium-frequency induction furnace for heating, wherein the heating temperature is 150-250 ℃ above the melting point of the alloy; pressing the prefabricated block which accounts for 1-10 wt% of the alloy into the alloy melt, and preserving heat: 1-30 minutes; refining, degassing and forming to obtain in-situ reaction TiB₂Particles and Al₂O₃The whisker is compounded and strengthened with the aluminum-based composite material.

2.The method of claim 1, wherein: the forming mode is pouring metal mold and sand mold or forming by extrusion and die casting.