CN110965059A

CN110965059A - Nano Fe-Al powder electron beam modified aluminum alloy

Info

Publication number: CN110965059A
Application number: CN201811143992.8A
Authority: CN
Inventors: 王洪伟
Original assignee: Individual
Current assignee: Individual
Priority date: 2018-09-29
Filing date: 2018-09-29
Publication date: 2020-04-07

Abstract

A nanometer Fe-Al powder electron beam modified aluminum alloy is characterized in that an electron beam scanning technology is utilized to carry out nanometer alloying treatment on the surface of aluminum alloy ADC12, and electron beam nanometer Al-Fe alloying can improve the hardness and wear resistance of an aluminum alloy material; along with the increase of the content of the nano Fe powder in the mixed powder, the hard alloy strengthening phase in the alloy layer is gradually increased, the hardness and the wear resistance of the alloy layer are also gradually improved, the hardness can reach 800HV at most, but cracks can occur in the structure and the uniformity is not good. When the content of the nano Fe powder in the mixed powder is 50%, the hardness and the wear resistance of the alloying layer are better, the heat-resistant hardness of the alloying layer can reach 300-400HV at 675K, and the wear loss is only 1/6 of the aluminum alloy base material.

Description

Nano Fe-Al powder electron beam modified aluminum alloy

Technical Field

The invention relates to an aluminum alloy material, in particular to a nano Fe-Al powder electron beam modified aluminum alloy.

Background

Aluminum alloys (including aluminum matrix composites) are widely used in automotive, aerospace, railway, and passenger vehicles because of their excellent properties. However, aluminum alloys have various disadvantages, such as low hardness and easy plastic deformation; the friction factor is high, the abrasion is large, and strain is easy; poor wear resistance of aluminum alloys due to poor lubrication, and the like. The surface hardness and the wear resistance of the aluminum alloy are improved, so that the wide application of the aluminum alloy in the new field can be expanded. The electron beam surface alloying is to rapidly melt one or more alloying elements into a matrix by using an electron beam surface modification technology, and to obtain a surface alloy layer with special properties by using energy conversion, structure change and the like.

And a scanning mode different from a pulse is selected in an energy injection mode by using an electron beam modification method which is higher in energy utilization rate and has no pollution to the surface. The aluminum alloy ADC12 added with the nano Al-Fe mixed powder in different proportions is subjected to surface strengthening treatment by using an electron beam scanning technology, and the proper proportion of the alloyed nano mixed powder is determined by analyzing the structure and the performance of a nano alloyed layer on the surface of the aluminum alloy, so that the aim of improving the hardness and the wear resistance of a matrix to the maximum extent is fulfilled.

Disclosure of Invention

The invention aims to improve the wear resistance of an aluminum alloy material and designs a Fe-Al powder electron beam modified aluminum alloy.

The technical scheme adopted by the invention for solving the technical problems is as follows:

the preparation raw materials of the nano Fe-Al powder electron beam modified aluminum alloy comprise: ADC12 aluminum alloy with test specimen dimensions of 40mm x 40 mm.

The preparation method of the nano Fe-Al powder electron beam modified aluminum alloy comprises the following steps: the electron beam scanning surface nano alloying is a metallurgical process, and the alloy reinforced nano Fe powder and a base material meet the thermodynamic condition of liquid solid melting, so that the solid melting reinforcement effect can be achieved under the rapid solidification condition after the electron beam scanning treatment, and the nano Fe powder can produce the reinforcement effect on an aluminum base. The center of the upper surface of the sample is milled into an annular groove with the inner diameter of 12mm, the outer diameter of 18mm and the groove depth of 2mm by adopting a coating method. Cleaning with acetone for 2min to remove oxide on the surface of the aluminum alloy, drying, etching with 10% NaOH for 10min, taking out, cleaning with anhydrous alcohol, and drying. The nano Fe-Al mixed powder with the nano Fe powder contents of 30%, 50% and 70% in the mixed powder is placed in containers with different numbers, the nano Al-Fe mixed powder is uniformly mixed by absolute ethyl alcohol, and is mixed into paste to be coated in an annular groove of a test piece, and the thickness of a precoating layer is 2.0 mm. After naturally airing in the air, the coating is pressed by using the pressure of 40kN to prepare a sample to be processed. The electron beam scanning equipment adopted in the experiment is an HDZ-6F high-voltage numerical control vacuum electron beam welding machine. The performance indexes are respectively 0-60kV of accelerating voltage, 0-120 mA of electron beam current, 0-3kHz of scanning frequency and 0-1000mA of focusing current. Placing into a vacuum chamber of an electron beam welding machine (vacuum degree of 10)^-2Pa) to which a surface scanning treatment is applied.

The detection steps of the nano Fe-Al powder electron beam modified aluminum alloy are as follows: the cross section of 1/8 is cut from the aluminum alloy sample treated by electron beam alloying, and the metallographic sample is made by coarse grinding, fine grinding, polishing and corrosion, and the size of the metallographic sample is 10mm multiplied by 10 mm. Observing the tissue structure by using a Tension metallographic microscope, testing the hardness by using an HMV-ZT Vickers microhardness tester, wherein the load is 0.1961N, and the loading time is 10 s; shooting a metallographic picture and testing EDS components by using a TSM-56102V scanning electron microscope; carrying out a friction and wear test by using an HT-500 high-temperature friction and wear testing machine; the phase composition of the e-beam alloyed layer was analyzed using a bruker D8X radiation diffractometer.

The invention has the beneficial effects that:

electron beam alloying can form a high-hardness strengthening layer with the thickness of 4-10 mm; the microstructure of the alloy layer can be divided into hypoeutectic (a-Al + FeAl)₃)、FeAl₃And Fe₂Al₅A hypereutectic structure of the intermetallic compound. Cracks appear in Fe₂Al₅Grain boundaries of the intermetallic compound; the hardness of the alloy layer increases along with the increase of the iron content, and when the mass fraction of Fe is 70%, the mass fraction of Fe is massive₂Al₅The hardness of the intermetallic compound composite structure can reach 800HV, but cracks appear and the tissue structure is not compact; when the mass fraction of Fe is 50%, FeAl in the structure₃The intermetallic compound alloy layer has good heat-resistant hardness, and the hardness can reach 300-400HV at 675K; the alloy layer with the Fe mass fraction of 50% has the best wear resistance, and is only 1/6 of the base material.

Detailed Description

Example 1:

the preparation raw materials of the nano Fe-Al powder electron beam modified aluminum alloy comprise: ADC12 aluminum alloy with test specimen dimensions of 40mm x 40 mm. The preparation method of the nano Fe-Al powder electron beam modified aluminum alloy comprises the following steps: the electron beam scanning surface nano alloying is a metallurgical process, and the alloy reinforced nano Fe powder and a base material meet the thermodynamic condition of liquid solid melting, so that the solid melting reinforcement effect can be achieved under the rapid solidification condition after the electron beam scanning treatment, and the nano Fe powder can produce the reinforcement effect on an aluminum base. The center of the upper surface of the sample is milled into an annular groove with the inner diameter of 12mm, the outer diameter of 18mm and the groove depth of 2mm by adopting a coating method. Cleaning with acetone for 2min to remove oxide on the surface of the aluminum alloy, drying, etching with 10% NaOH for 10min, taking out, cleaning with anhydrous alcohol, and drying. Placing the mixed powder containing 30%, 50% and 70% of nano Fe powder in different containers, mixing with anhydrous alcohol, and making into pasteIn the annular groove, the precoat thickness was 2.0 mm. After naturally airing in the air, the coating is pressed by using the pressure of 40kN to prepare a sample to be processed. The electron beam scanning equipment adopted in the experiment is an HDZ-6F high-voltage numerical control vacuum electron beam welding machine. The performance indexes are respectively 0-60kV of accelerating voltage, 0-120 mA of electron beam current, 0-3kHz of scanning frequency and 0-1000mA of focusing current. Placing into a vacuum chamber of an electron beam welding machine (vacuum degree of 10)^-2Pa) to which a surface scanning treatment is applied. The detection steps of the nano Fe-Al powder electron beam modified aluminum alloy are as follows: the cross section of 1/8 is cut from the aluminum alloy sample treated by electron beam alloying, and the metallographic sample is made by coarse grinding, fine grinding, polishing and corrosion, and the size of the metallographic sample is 10mm multiplied by 10 mm. Observing the tissue structure by using a Tension metallographic microscope, testing the hardness by using an HMV-ZT Vickers microhardness tester, wherein the load is 0.1961N, and the loading time is 10 s; shooting a metallographic picture and testing EDS components by using a TSM-56102V scanning electron microscope; carrying out a friction and wear test by using an HT-500 high-temperature friction and wear testing machine; the phase composition of the e-beam alloyed layer was analyzed using a bruker D8X radiation diffractometer.

Example 2:

the electron beam treated strengthening layer and matrix structure are obviously changed, after the surface of the electron beam is alloyed, 3 regions are formed in the strengthening layer, and respectively are matrix region, transition region and alloying region, the matrix structure is formed from eutectic and granular Si crystal, in the transition region, i.e. remelting region of molten pool, the crystal grain of the structure is relatively fine and small, and because the cooling speed of transition region is quick due to heat conduction action of matrix in the course of scanning electron beam, the Si crystal phase can not be separated out from matrix, and can be dissolved in eutectic to make crystal grain relatively fine, after the nano Al-Fe mixed powder is added on the surface of aluminium alloy, the molten nano Fe powder in the matrix can be formed into new α phase and α (Si + Al) binary eutectic, small quantity of coarse crystal silicon and strip needle-like β (Al + Al) binary eutectic₉Si₂Fe₂) The phase and a part of the unmelted nanometer powder are dissolved in the matrix to form new FeAl₃And Fe₂Al₅The phase of the mixture is shown as phase,

example 3:

the hardness gradually decreases but is higher than the matrix with increasing distance from the surface. The thickness of the alloy layer in the strengthening area of the electron beam surface treatment is about 6mm, and the average hardness of the alloy layer is 3 times of that of the base material, because the surface alloy layer structure is formed by new FeAl₃And Fe₂Al₅High refinement of grains in the texture of the melting zone, resulting in non-equilibrium eutectic and lathy needle-like β (Al)₉Si₂Fe₂) The compound, resulting in a higher microhardness than the matrix. When the thickness is 10mm from the surface, the hardness of the base material enters the base material area and is unchanged, and the hardness is consistent with the characteristics of the microstructure.

Example 4:

the wear resistance analysis is to carry out a wear test on the aluminum alloy strengthened layer after the electron beam scanning nano alloying treatment under the oil lubrication condition and the load of 300N. The abrasion loss increases with the increase of the abrasion time, and the abrasion loss of the electron beam surface treatment layer is far smaller than that of the base material. The abrasion loss of the surface alloy layer is 1/6-1/2 of the abrasion loss of the base material, and the conclusion is consistent with the test results of the structure and the microhardness, which shows that the abrasion resistance of the structure is greatly improved relative to the base material in the alloying layer area and the transition area, and the electron beam nano alloying strengthening treatment can improve the structure and the performance of the aluminum alloy material.

Example 5:

when the mass fraction of Fe in the FeAl mixed powder is 30%, the alloy layer has a hypoeutectic structure (a-Al + FeAl)₃) And FeAl₃The composition can obviously see loose and uneven tissue structure; when the mass fraction of Fe is 50%, the obtained alloy layer structure is formed by strip-shaped FeAl₃Phase composition, uniform and fine tissue; when the mass fraction of Fe is 70%, the structure is composed of blocky Fe₂Al₅The compound composition, cracks are present at the grain boundaries. The mass fraction of Fe is 70%, and the Fe has block-shaped Fe₂Al₅The alloy layer hardness of the structure is about 800 HV; the Fe mass fraction of the Fe alloy is 50 percent, and the Fe alloy has strip-shaped FeAl₃The alloy layer hardness of the structure is 400 HV; the Fe mass fraction of the eutectic structure (a-Al + FeAl) is 30 percent₃) And FeAl₃The alloy layer hardness of the structure was 200 HV. ByTherefore, the microhardness of the alloy layer is improved along with the increase of the mass fraction of the nano Fe in the mixture, because the electron beam scanning alloying treatment is carried out after the nano Fe-Al mixed powder material is added on the surface of the aluminum alloy, the solubility of the solid solution in the electron beam alloy layer is improved, the solid solution strengthening is generated, the hardness is improved, and particularly, FeAl appears in the structure₃、Fe₂Al₅Such compounds cause a significant increase in hardness. The hardness of the alloy layer increases along with the increase of the Fe mass fraction, and the hardness of the alloy layer exceeds 800HV when the mass fraction of the mixed powder nano Fe is more than 70%; cracks in the alloy layers occur when the hardness is higher than 600HV, because brittle, massive Fe is formed in these alloy layers₂Al₅A compound; when the content of the mixed powder nano Fe is 38-58%, a compact and uniform tissue structure without cracks can be obtained. The substrate and the substrate have FeAl₃The hardness of the compound tissue has similar change rule along with the temperature increase, but has FeAl at 675K₃The compound still has the tissue hardness of 300-400HV, so the compound has fine needle-shaped FeAl₃The intermetallic compound has good heat resistance. And has bulk Fe₂Al₅The hardness of the compound tissue is substantially unaffected by temperature.

Example 6:

the abrasion loss of the alloy layer with the Fe mass fraction of 30 percent is lower than that of the base material; the wear amount of the alloy layer with the Fe mass fraction of 50% and 70% is much lower than that of the base material, and the wear resistance of the alloy layer with the Fe mass fraction of 70% is better than that of 50%. When the abrasion time is 6-8h, the abrasion loss of the alloy layer with the Fe mass fraction of 70% and 50% is almost consistent; when the abrasion time reaches 10 hours, the abrasion resistance of the alloy layer with 70% of Fe mass fraction is slightly higher than that of the nano Fe powder alloy layer with 50% of Fe mass fraction, and the reasons for the abrasion are as follows: the alloy layer with a Fe mass fraction of 70% has a high hardness, but the alloy layer has a small thickness and cracks in the structure, while the alloy layer with a Fe mass fraction of 50% has a dense and thick structure, which are consistent with the above results of the microstructure and micro-hardness. The electron beam alloying can improve the hardness and the wear resistance of the structure, and the wear resistance of the alloy layer sample with the Fe mass fraction of 50 percent is obviously improved as the wear amount of the 1/6 of the aluminum alloy matrix.

Claims

1. A nanometer Fe-Al powder electron beam modified aluminum alloy is prepared from the following raw materials: ADC12 aluminum alloy with test specimen dimensions of 40mm x 40 mm.

2. The nano Fe-Al powder electron beam modified aluminum alloy as claimed in claim 1, wherein the preparation steps of the nano Fe-Al powder electron beam modified aluminum alloy are as follows: the electron beam scanning surface nano alloying is a metallurgical process, the alloy reinforced nano Fe powder and base material can meet the thermodynamic condition of liquid solid melting, and can obtain solid melting reinforcement effect under the quick solidification condition after electron beam scanning treatment, so that the nano Fe powder can produce reinforcement action on aluminium base body, and said alloy reinforced nano Fe powder and base material are undergone the process of coating method, and the centre of upper surface of sample is milled and processed into ring groove whose inner diameter is 12mm, outer diameter is 18mm and groove depth is 2mm, and firstly cleaned by acetone for 2min to remove oxide on the surface of aluminium alloy, then dried, then etched by 10% NaOH for 10min, taken out, cleaned and dried by absolute ethyl alcohol, and the nano Fe-Al mixed powder whose nano Fe powder content is 30%, 50% and 70% respectively is placed in containers with different number, and the nano Al-Fe mixed powder is uniformly mixed by using absolute ethyl alcohol, and mixed into paste-like material and coated in the ring groove of test piece, the thickness of the precoating layer is 2.0mm, after naturally drying in the air, the precoating layer is pressed by 40kN pressure to prepare a sample to be processed, the electron beam scanning equipment adopted in the experiment is an HDZ-6F high-pressure numerical control vacuum electron beam welding machine, the performance indexes of the electron beam scanning equipment are respectively 0-60kV acceleration voltage, 0-120 mA electron beam current, 0-3kHz scanning frequency and 0-1000mA focusing current, and the electron beam scanning equipment is put into a vacuum chamber of the electron beam welding machine (the vacuum degree is 10)^-2Pa) to which a surface scanning treatment is applied.

3. The nano Fe-Al powder electron beam modified aluminum alloy as claimed in claim 1, wherein the detection steps of the nano Fe-Al powder electron beam modified aluminum alloy are as follows: cutting 1/8 cross section from the aluminum alloy sample processed by electron beam alloying, and making into metallographic sample by coarse grinding, fine grinding, polishing and corrosion, wherein the size of the metallographic sample is 10mm multiplied by 10mm, the organization structure is observed by a Tension metallographic microscope, the hardness is tested by an HMV-ZT micro-hardness meter, the load is 0.1961N, and the loading time is 10 s; shooting a metallographic picture and testing EDS components by using a TSM-56102V scanning electron microscope; carrying out a friction and wear test by using an HT-500 high-temperature friction and wear testing machine; the phase composition of the e-beam alloyed layer was analyzed using a bruker D8X radiation diffractometer.

4. The nano Fe-Al powder electron beam modified aluminum alloy as claimed in claim 1, wherein the electron beam alloying can form a high hardness strengthening layer with a thickness of 4-10 mm; the microstructure of the alloy layer can be divided into hypoeutectic (a-Al + FeAl)₃)、FeAl₃And Fe₂Al₅Hypereutectic structure of intermetallic compound, cracks appearing in Fe₂Al₅Grain boundaries of the intermetallic compound; the hardness of the alloy layer increases along with the increase of the iron content, and when the mass fraction of Fe is 70%, the mass fraction of Fe is massive₂Al₅The hardness of the intermetallic compound composite structure can reach 800HV, but cracks appear and the tissue structure is not compact; when the mass fraction of Fe is 50%, FeAl in the structure₃The intermetallic compound alloy layer has good heat-resistant hardness, and the hardness can reach 300-400HV at 675K; the alloy layer with the Fe mass fraction of 50% has the best wear resistance, and is only 1/6 of the base material.