CN109594002A

CN109594002A - A kind of more pivot medium entropy alloys and preparation method thereof

Info

Publication number: CN109594002A
Application number: CN201811465459.3A
Authority: CN
Inventors: 刘宁; 范佳承; 陈晨; 彭振; 杜文栋; 王小京
Original assignee: Jiangsu University of Science and Technology
Current assignee: Hubei Yifei Composite Material Co ltd
Priority date: 2018-12-03
Filing date: 2018-12-03
Publication date: 2019-04-09
Anticipated expiration: 2038-12-03
Also published as: CN109594002B

Abstract

The invention relates to a multi-principal element medium-entropy alloy and a preparation method thereof. The composition of the multi-principal element medium-entropy alloy is Fe ₂₅ Ni ₂₅ Co _50-x Mo _x (0≤x≤50) in atomic percentage; the composition is Fe The medium-entropy alloy of ₂₅ Ni ₂₅ Co ₂₅ Mo ₂₅ has the best comprehensive mechanical properties: the hardness is 411HV, the yield strength is 1520MPa, the compressive strength is 2056MPa, and the plasticity is 31%. The medium-entropy alloy of the present invention is prepared by an arc melting method, and the preparation method has a simplified process, lower difficulty and lower cost.

Description

A kind of more pivot medium entropy alloys and preparation method thereof

Technical field

The present invention relates to metal material and its preparation fields, in particular to a kind of more pivot medium entropy alloys and its preparation Method.

Technical background

In thermodynamics, entropy represents the confusion degree of system, and entropy is bigger, and the confusion degree of system is bigger, when entropy reaches When to maximum value, system tends towards stability, and reaches balance.Novel more pivot metal materials are with higher system △ S_mixValue is different from Conventional alloys, for conventional alloys based on a kind of element, the entropy of mixing is less than 0.693R, and (R is gas constant R=8.314J/ MolK) belong to low entropy alloy, the alloy being made of 2~4 kinds of elements, the entropy of mixing between 0.693R~1.61R, referred to as in Entropy alloy.The alloy of 5 kinds and above element composition, the entropy of mixing is on 1.61R, referred to as high-entropy alloy.

The high entropy of mixing can be effectively reduced the Gibbs free energy (△ G=△ H-T △ S) of system, to make alloy System is more stable.Generally, although having more constituent element, multi-principal elements alloy tends to form simple phase in phase composition Structure, this is conducive to the raising of alloy property.High-entropy alloy is easy to obtain because having high entropy and atom to be not easy the characteristic spread Thermal stability high solid solution phase and nanostructure or even non crystalline structure are obtained, while having some conventional alloys institutes incomparable Excellent properties, such as high intensity, hardness, wearability, preferable plasticity and toughness, good structure stability and corrosion resistance etc..

AlCoCrCuFeMo_xIn Ni system high-entropy alloy, as Mo content increases, the intensity of alloy is significantly improved, but simultaneously Along with the severe exacerbation of alloy plasticity；AlCoCrCuFeMo_0.6The compression strength of Ni alloy reaches peak 2820MPa, and strains Value is only 1.1%.This seminar previous experiments result of study shows to wait atomic percents CoCrFeMoNi multi-principal high-entropy alloy Compression strength reach 2427MPa, yield strength 1250MPa, while plastic strain is 33%.Patent (CN 201610759867.4 with CN 201610758896.9) conjunction of TiCuAlCrMoNi and TiCuAlCrMoNb high entropy is disclosed respectively Gold, two kinds of alloys all have higher yield strength, tensile strength and certain elongation percentage, while fine corrosion resistance, but Above-mentioned high-entropy alloy includes a variety of refractory metals there are a common problem, i.e. alloy, and smelting technology is complicated, at high cost.

Therefore, on the basis of guaranteeing preferable strong plasticity cooperation, technology difficulty is reduced as much as possible, is saved cost, is Middle and high entropy Alloyapplication problems faced.

Summary of the invention

One of the objects of the present invention is to provide a kind of more pivot medium entropy alloys.

In order to achieve the above-mentioned object of the invention, technical scheme is as follows:

A kind of more pivot medium entropy alloys, it is characterised in that: its ingredient is Fe by atomic percent₂₅Ni₂₅Co_50-xMo_x, wherein 0≤x≤50。

Further preferably, ingredient is Fe by atomic percent₂₅Ni₂₅Co₂₅Mo₂₅。

Further preferably, ingredient is Fe by atomic percent₂₅Ni₂₅Co_50-xMo_x, wherein 0≤x < 25.

Further preferably, ingredient is Fe by atomic percent₂₅Ni₂₅Co_50-xMo_x, wherein 25 x≤50 <.

Further preferably, ingredient is Fe by atomic percent₂₅Ni₂₅Co_50-xMo_x, wherein 0≤x < 15.

Further preferably, ingredient is Fe by atomic percent₂₅Ni₂₅Co_50-xMo_x, wherein 15≤x≤50.

The second object of the present invention is to provide the preparation method of more pivot medium entropy alloys.Concrete scheme is as follows:

A kind of preparation method of more pivot medium entropy alloys, comprising the following steps:

Step 1: be converted into mass percentage according to atomic percentage content, and by the metal former material of purity >=99.95% Material is matched according to mass percentage accurate weighing, is used for molten alloy；

Step 2: melting uses non-consumable arc furnace, the load weighted simple substance raw material of step 1 is put into vacuum arc In water cooled copper mould melting pond in furnace, oxygen uptake titanium is placed among crucible, then fire door is closed, tightens knob；

Step 3: by electric arc stove evacuation, when vacuum degree reaches 5 × 10^-3Purity >=99.99wt% is filled with after Pa into furnace Argon gas to normal pressure, so carry out " vacuumizing-applying argon gas " 1~3 time, then carry out melting, melting is overturn after founding ingot, such as This melt back is to uniform, furnace cooling ingot.

Further preferably, melting electric current described in step 3 is 350~450A.

Beneficial effects of the present invention:

Compared with conventional alloys, more pivot medium entropy alloys intensity with higher of the invention and preferably plasticity；With property CoCrFeMoNi high-entropy alloy that can be close compares, and the preparation method technique of medium entropy alloy of the invention simplifies, due to infusibility gold Melting is uniform less and more easily for category, and cost is relatively low, is conducive to produce.

Detailed description of the invention

Due to Fe and Ni ingredient it is known that for the sake of simplifying, the ingredient of Co and Mo is only shown in attached drawing.

Fig. 1 is the Fe of embodiment₂₅Ni₂₅Co_50-xMo_xThe XRD spectrum of medium entropy alloy, wherein Fig. 1 a is Fe₂₅Ni₂₅Co_50-xMo_x (when 25 < x≤50, x is respectively 30,35,40,45,50) XRD diagram of medium entropy alloy, and Fig. 1 b is Fe₂₅Ni₂₅Co_50-xMo_x(0≤x When≤25, x is respectively 0,5,10,15,20,25) XRD diagram of medium entropy alloy.

Fig. 2 is the Fe of embodiment₂₅Ni₂₅Co_50-xMo_xThe solidified structure photo of medium entropy alloy, wherein Fig. 2 a~Fig. 2 k be Fe₂₅Ni₂₅Co_50-xMo_xSEM figure of the medium entropy alloy when x is respectively 0,5,10,15,20,25,30,35,40,45,50.

Fig. 3 is the Fe of embodiment₂₅Ni₂₅Co_50-xMo_xThe compressive stress strain curve and hardness of medium entropy alloy, wherein Fig. 3 a For Fe₂₅Ni₂₅Co_50-xMo_x(when 25 < x≤50, x is respectively 30,35,40,45,50) compression stress-strain of medium entropy alloy is bent Line chart, Fig. 3 b are Fe₂₅Ni₂₅Co_50-xMo_x(when 25≤x≤50, x is respectively 25,30,35,40,45,50) Vickers of medium entropy alloy Hardness figure, Fig. 3 c are Fe₂₅Ni₂₅Co_50-xMo_x(when 0≤x≤25, x is respectively 0,5,10,15,20,25) compression of medium entropy alloy Stress-strain curve, Fig. 3 d are Fe₂₅Ni₂₅Co_50-xMo_x(when 0≤x≤25, x is respectively 0,5,10,15,20,25) medium entropy conjunction The Vickers hardness figure of gold.

Specific embodiment

The present invention is described in detail below by way of specific embodiment, but this embodiment is merely illustrative, It does not form any restrictions to the present invention.

Embodiment

1. Fe of the invention₂₅Ni₂₅Co_50-xMo_xThe preparation process of medium entropy alloy is as follows:

Step 1: accurately calculating high pure metal raw material (>=99.95%) and weigh according to mass percentage, for molten Alloy is refined to use；

Step 2: WK type non-consumable arc furnace is used, load weighted simple substance raw material is put into vacuum arc furnace ignition In water cooled copper mould melting pond, oxygen uptake titanium is placed among crucible, then fire door is closed, tightens knob；

Step 3: by electric arc stove evacuation, when vacuum degree reaches 5 × 10^-399.99wt% purity is filled with after Pa into furnace Argon gas reduces volatilization to normal pressure when being to keep alloy not oxidized and alloy melting in this way.It carries out " vacuumizing-filling in this way Argon gas " three times, can melting.Melting about 30 seconds, alloy is overturn under 400A electric current, repeatedly founding 5 times it is uniform to ingredient, After the completion of melting, furnace cooling obtains the uniform Fe of ingredient₂₅Ni₂₅Co_50-xMo_xAlloy pig.

2. the institutional framework and performance of alloy

1) X-ray diffraction (XRD) test and crystal species analysis

Sample is cut with Metallographic Specimen Cutting Machine, then with #600 silicon carbide paper ground on levigator one it is smooth flat Whole plane is to do XRD analysis, and 2 θ range of scanning angle is 30-80 °, and scanning speed is 6 °/min.

Fig. 1 is Fe₂₅Ni₂₅Co_50-xMo_xThe XRD analysis map of medium entropy alloy, wherein Fig. 1 a is Fe₂₅Ni₂₅Co_50-xMo_x(25 When < x≤50, x is respectively 30,35,40,45,50) XRD diagram of medium entropy alloy, and Fig. 1 b is Fe₂₅Ni₂₅Co_50-xMo_x(0≤x≤25 When, x is respectively 0,5,10,15,20,25) XRD diagram of medium entropy alloy.In conjunction with Fig. 1 a and Fig. 1 b it is found that with Mo constituent content Increase, the reduction of Co constituent content, Fe₂₅Ni₂₅Co_50-xMo_xIt is the phase structure of multi-principal elements alloy by the single opposite FCC+ of FCC BCC+ topology solid matter phase or the transformation of MoNi phase heterogeneous structure.

Equal atomic percents Fe₂₅Ni₂₅Co₂₅Mo₂₅The crystal structure of alloy is mainly by simple face-centered cubic phase FCC Xiang Yutuo Flutter solid matter phase (including μ phase and σ phase) composition.Wherein FCC is similar is similar to Fe0.64Ni0.36 phase, and dot-pattern space group is Fm3m, Lattice constant is a=b=c=3.592.Due to the presence of systematic extinction law in X-ray diffraction spectrum, only when indices of crystallographic plane H, K, when L is all odd number or even number, face-centered cubic lattice just has diffraction phenomena, so diffraction corresponding to simple face-centered cubic phase Peak is respectively (111), (200), (220) and (311) crystal face.μ phase is the complicated ordered phase similar to Co7Mo6 phase, and point type is empty Between group be R-3m, lattice constant a=b=4.672, c=25.617.σ phase is the complicated ordered phase similar to Co2Mo3 phase, Dot-pattern space group is P42/mnm, lattice constant a=b=9.229, c=4.827.

2) scanning electron microscope (SEM) structure observation and analysis

The advanced line of alloy is cut into the pole of certain length, then it is inlayed, 180# is utilized after inlaying, 400#, 800#, 1000#, 1500#, 2000# silicon carbide paper carry out water mill and polish.Then corroded using chloroazotic acid, the examination after corrosion Sample carries out solidified structure shooting using scanning electron microscope.

Fig. 2 is Fe₂₅Ni₂₅Co_50-xMo_xThe solidified structure photo of medium entropy alloy, wherein Fig. 2 a~Fig. 2 k be in order Fe₂₅Ni₂₅Co_50-xMo_xSEM figure of the medium entropy alloy when x is respectively 0,5,10,15,20,25,30,35,40,45,50.It can send out It is existing, Fe₂₅Ni₂₅Co_50-xMo_xMedium entropy Solidification Structure is mainly made of primary dendrite and interdendritic Eutectic Layer lamellar structure. From Fig. 2 a~Fig. 2 c as can be seen that as x < 15%, Solidification Structure is simple dendrite；It can be with from Fig. 2 d~Fig. 2 k Find out, as x >=15%, Fe₂₅Ni₂₅Co_50-xMo_xMulti-principal elements alloy solidified structure dendrite and interdendritic eutectic structure.

3) alloy compression experiment

By the advanced line cutting of sample, being prepared into diameter is 5mm, is highly the standard compression test rod of 10mm, utilizes water Dry sanding paper polishes smooth both ends smooth.If both ends are not horizontal, error will be generated in compression process, influences test result. Room temperature compression experiment is carried out on universal testing machine.And compressive stress strain curve is drawn with Origin software.

4) alloy rigidity is tested

The advanced line of alloy is cut into the pole of certain length, then it is inlayed, 180# is utilized after inlaying, 400#, 800#, 1000#, 1500#, 2000# silicon carbide paper carry out water mill and polish.Then corroded using chloroazotic acid, the examination after corrosion Sample measures the hardness of alloy using micro Vickers.The load chosen in this experiment be 25K, load retention time 10s, Hardness number is read after unloading.It measures 7 groups of hardness numbers and records, calculate average value.

Fig. 3 show Fe₂₅Ni₂₅Co_50-xMo_xThe mechanical property of more pivot medium entropy alloys, wherein Fig. 3 a is Fe₂₅Ni₂₅Co_50- _xMo_x(when 25 < x≤50, x is respectively 30,35,40,45,50) the compressive stress strain curve figure of medium entropy alloy, and Fig. 3 b is Fe₂₅Ni₂₅Co_50-xMo_x(when 25≤x≤50, x is respectively 25,30,35,40,45,50) the Vickers hardness figure of medium entropy alloy, Fig. 3 c For Fe₂₅Ni₂₅Co_50-xMo_x(when 0≤x≤25, x is respectively 0,5,10,15,20,25) compression stress-strain of medium entropy alloy is bent Line chart, Fig. 3 d are Fe₂₅Ni₂₅Co_50-xMo_x(when 0≤x≤25, x is respectively 0,5,10,15,20,25) Vickers of medium entropy alloy is hard Degree figure.It can be seen that the increase with Mo constituent content, the reduction of Co constituent content, Fe from Fig. 3 b and Fig. 3 d₂₅Ni₂₅Co_50- _xMo_xThe hardness of multi-principal elements alloy increases to 953.53HV from 137.28HV.It can be seen that from Fig. 3 a and Fig. 3 c Fe₂₅Ni₂₅Co₂₅Mo₂₅Alloy and Fe₂₅Ni₂₅Mo₅₀Alloy obtains maximum compression strength (2056MPa) and yield strength respectively (1928MPa)；According to Fig. 1 a and Fig. 1 b: the alloy of single-phase FCC configuration has excellent plasticity but intensity lower, and FCC+ BCC+ topology solid matter phase/MoNi phase heterogeneous structure alloy intensity with higher, but plasticity is lower with the raising of intensity.

As can be seen that Fe25Ni25Co25Mo25 alloy has preferably strong plasticity cooperation, resistance to compression from Fig. 3 a- Fig. 3 d Intensity is 2056MPa, yield strength 1520MPa, while being able to maintain 31% plastic strain.

Claims

1. A multi-principal medium entropy alloy, characterized in that: its composition is Fe ₂₅ Ni ₂₅ Co _50-x Mo _x by atomic percentage, wherein 0≤x≤50.

2 . The multi-principal medium-entropy alloy according to claim 1 , wherein the composition is Fe ₂₅ Ni ₂₅ Co ₂₅ Mo ₂₅ in atomic percentage. 3 .

3 . The multi-principal medium-entropy alloy according to claim 1 , wherein the composition is Fe ₂₅ Ni ₂₅ Co _50-x Mo _x by atomic percentage, wherein 0≦x<25. 4 .

4 . The multi-principal medium-entropy alloy according to claim 1 , wherein the composition is Fe ₂₅ Ni ₂₅ Co _50-x Mo _x in atomic percentage, wherein 25<x≦50. 5 .

5 . The multi-principal medium-entropy alloy according to claim 1 , wherein the composition is Fe ₂₅ Ni ₂₅ Co _50-x Mo _x by atomic percentage, wherein 0≦x<15. 6 .

6 . The multi-principal medium-entropy alloy according to claim 1 , wherein the composition is Fe ₂₅ Ni ₂₅ Co _50-x Mo _x by atomic percentage, wherein 15≤x≤50. 7 .

7. A preparation method of the multi-principal medium-entropy alloy according to any one of claims 1 to 6, characterized in that, comprising the following steps:

Step 1: Calculate the mass percentage content according to the atomic percentage content, and weigh and proportion the metal raw materials with a purity of ≥99.95% according to the mass percentage content for use in smelting alloys;

Step 2: A non-consumable vacuum arc furnace is used for smelting, and the elemental raw materials weighed in step 1 are put into the water-cooled copper mold smelting pool in the vacuum arc furnace, and oxygen-absorbing titanium is placed in the middle of the crucible, then the furnace door is closed, and the knob is tightened. ;

Step 3: Evacuate the electric arc furnace. When the degree of vacuum reaches 5×10 ^-3 Pa, fill the furnace with argon with a purity of ≥99.99wt% to normal pressure, and perform "evacuating-argon filling" 1-3 Second, and then smelted, cast into ingots and then turned over and smelted, so that the smelting is repeated until uniform, and cooled with the furnace into ingots.

8 . The method for preparing a multi-principal medium entropy alloy according to claim 7 , wherein the smelting current in step 3 is 350-450 A. 9 .