CN106968013A - A kind of method for preparing iridium monocrystalline - Google Patents

A kind of method for preparing iridium monocrystalline Download PDF

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CN106968013A
CN106968013A CN201710260495.5A CN201710260495A CN106968013A CN 106968013 A CN106968013 A CN 106968013A CN 201710260495 A CN201710260495 A CN 201710260495A CN 106968013 A CN106968013 A CN 106968013A
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iridium
rod
electron gun
melting
speed
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CN106968013B (en
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王斌强
李双明
钟宏
胡锐
杨劼人
刘毅
罗锡明
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Northwestern Polytechnical University
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    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B13/00—Single-crystal growth by zone-melting; Refining by zone-melting
    • C30B13/16—Heating of the molten zone
    • C30B13/22—Heating of the molten zone by irradiation or electric discharge
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B13/00—Single-crystal growth by zone-melting; Refining by zone-melting
    • C30B13/28—Controlling or regulating
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
    • C30B29/02—Elements

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Manufacture And Refinement Of Metals (AREA)
  • Crystals, And After-Treatments Of Crystals (AREA)

Abstract

A kind of method for preparing iridium monocrystalline, zone length control more difficult the problem of big for iridium density, iridium monocrystalline is prepared using electro-beam floating zone domain melting technique.By reasonable control electric current parameter in preparation, melting zone is maintained at original charge bar by surface tension and solidified between charge bar, and the directional solidification when electron gun is slowly moved along its length, so as to be grown to serve as monocrystalline along the length direction of whole charge bar.By rationally controlling electron gun walking speed, i.e. directional solidification rates, iridium monocrystalline is obtained.The preparation process of the present invention has repeatability, repeatedly prepares result in success under the same conditions.

Description

A kind of method for preparing iridium monocrystalline
Technical field
Field is manufactured the present invention relates to metal directional solidification, is specifically that one kind utilizes electro-beam floating zone domain melting technique (EBFZM) method for preparing rare precious metal iridium monocrystalline.
Background technology
Iridium belongs to platinum group metal, the big (22.42g/cm of fusing point height (2443 DEG C), density3), hardness height (modulus of elasticity (E= 527GPa, Poisson's ratio μ=0.26), high-temperature behavior are good, chemical property is stable, and 2300 DEG C can be applied in oxidizing atmosphere, It is the metal uniquely can more than 1600 DEG C still with good mechanical properties.At present, iridium is applied to Aero-Space, high energy thing The high-technology fields such as reason, weapons, mechano-electronic, medical science.For example：In the heart component-mono- of growth high-quality high power laser Brilliant yttrium-aluminium-garnet (fusing point is close to 2000 DEG C), using the monocrystalline iridium crucible of purity 99.995%, the monocrystalline quality of pull-out is high, makes With the life-span up to 2500~3000h.In semiconductor applications, the iridium monocrystalline of [100] orientation is that acquisition diamond single crystal material is best Epitaxial growth base material.
When iridium grows monocrystalline with Physical, suitable crucible is had no for melting, can only use area's melting method without crucible, And this method and alloy density are closely related, density is bigger, and stability is poorer, and difficulty is higher.It is possible to prepare iridium monocrystalline Method mainly has 3 kinds：Electro-beam floating zone domain smelting process, light beam floating zone melting method and plasma arc melting method.
Electro-beam floating zone domain smelting process (EBFZM) is to prepare refractory metal monocrystalline most ripe process, and it is 20 Proposed first by W.F.Pfann et al. the fifties in century, its principle is：The electronics of negative electrode (W filaments) transmitting of electron gun, through poly- Burnt system is focused into electron beam, and high velocity bombardment anode charge bar, makes kinetic energy be converted into heat after high voltage electric field accelerates, on charge bar Form narrow melting zone.Melting zone is maintained at original charge bar by surface tension and solidified between charge bar, and is grown in electron gun along it Directional solidification when degree direction is slowly moved, so that monocrystalline is grown to serve as along the length direction of whole charge bar, its schematic diagram such as Fig. 1 It is shown.This method have the advantages that energy density it is high, without crucible pollution, control is simple and precision is high, it can remove gas and It is mingled with to purify metals, the monocrystal with desired tissue structure can be grown again, as prepares the important of high-purity refractory metal Method.
The key that EBFZM technologies prepare refractory metal monocrystalline is the stability in metal melting zone to be kept, and melting zone stability Abutment surface tension force is maintained, and its Stable Length is proportional to (γ/ρ g)1/2(wherein, γ is smelt surface tension, and ρ is fusant density, G is acceleration of gravity).Proposed in Publication No. CN106381519A innovation and creation《One kind control large scale molybdenum niobium is closed The method of golden monocrystalline bar isodiametric growth》.This method is equally carried out using electro-beam floating zone domain melting technique to molybdenum niobium alloy Melting, but unlike, this method carries out crystal growth using seed-grain method, and molybdenum niobium alloy density is much smaller than iridium, surface tension With respect to iridium than larger, so molybdenum niobium alloy monocrystal growth difficulty is smaller.Wang Hong exists《The electro-beam floating zone of refractory metal molybdenum crystal Domain directional solidification processes research》.(electron-beam floating zone melting directional solidification processes research [D] of Wang Hong refractory metal molybdenum crystal Northwestern Polytechnical University, 2007.).In Wang Hong research, the fusing point (2610 DEG C) of molybdenum is close with iridium in single crystal preparation, and density is 10.2g/cm3, is less than the half of metal iridium density, and metal iridium single crystal preparation difficulty is significantly larger than molybdenum single crystal.Document《Study of the microstructure of a Ni(100)single crystal grown by electron beam floating zone melting》(Alonzo V,Berthier F,Glebovsky V G,et al.Study of the microstructure of a Ni(100)single crystal grown by electron beam floating zone melting[J].Journal of Crystal Growth,1995,156(4):480-486.) and《Growing Single Crystals of High-Purity Refractory Metals by Electron-Beam Zone Melting》(Glebovsky V G,Semenov V N.Growing Single Crystals of High-Purity Refractory Metals by Electron-Beam Zone Melting[J].High Temperature Materials&Processes,1995,14(2):121-130.).Report the refractory metal single crystal preparation such as W, Ni.Document Deformation of Zone-melted Iridum Single Crystals(Hieber H,Mordike B L,Haasen P.Deformation of Zone-melted Iridium Single Crystals[J].Platinum Metals Rev, 1964.) it is feasible to report area in melt iridium monocrystalline, but Φ 4mm iridium rod is used in article, and experimental facilities is without identical. And inventor uses Φ 6mm iridium rod, diameter is bigger, and growth difficulty is bigger.So experiment needs further exploration.It is domestic at present Only a small number of units can prepare iridium, and wherein Kunming Institute of Precious Metals prepares the technics comparing maturation of iridium, but does not have so far Research unit discloses the growth for setting foot in iridium monocrystal.If metal iridium monocrystalline can grow success, then low, close for fusing point The directive function and promotional value of the small other infusibility metal crystals growth of degree are self-evident.
In addition, Li Shuan penetrating judgments confide a stratagem to calculate metal iridium surface tension can stablize melting zone highly be 8.4mm.(Li Shuan Bright, Geng Zhenbo, Hu Rui wait the effect of crystal growths angle and freezing rate to noble metal electron beam zone melting crystal growth [J] Acta Physica Sinicas, 2015,64 (10):292-299.), the theoretical parameter of preciousness is provided for experiment, has finger to follow-up work Effect is led, helps accurately to control iridium monocrystalline growing process.
The content of the invention
To overcome in the prior art because iridium density is big, the more difficult control of zone length, the growing method of iridium monocrystal there is no Deficiency, the present invention propose a kind of method for preparing iridium monocrystalline.
The present invention detailed process be：
Step 1, the correction and surface treatment of iridium rod.Linearity≤1mm/m of iridium rod after the correction.
Plus heater current and main high pressure step 2,：
Iridium rod clamping after the correction is in vacuum electron beam zone melting furnace between the upper grip and lower chuck of clamping device. Alcohol washes seal ring for furnace lid and electron gun gun body.Close area electron beam smelting furnace；ON cycle cooling water；It is evacuated to higher than 1 ×10-3Start after Pa plus heater current and main high pressure.
During described plus heater current, risen using 20A → 30A → 40A staged, every 2min plus 10A, i.e., when described Heater current adds to 20A, stops 2min；Within dwell time 2min, keep filament current value constant.Add heater current after 2min again To 30A, then stop 2min and keep the filament current value constant；Continue heater current adding to 40A after 2min.
Start when heater current is stabilized to after 40A to area electron beam smelting furnace plus main high pressure.
Described plus main high pressure uses staged pressuring method：Main high pressure adds to 16KV from 0, and the main high pressure often increases therebetween 1KV is to stop 1min, i.e., stop 1min when main high pressure adds to 1KV from 0；Main high-voltage value is kept within the 1min of stopping not Become.Continue to add after 1min and stop 1min during 2KV and keep main high-voltage value constant；So often 1KV is added to stop 1min, until the main height Pressure adds to 16KV.
Step 3, degasification：By ring-type electron gun, the degasification by the way of quickly repeatedly walking：The electron gun speed of travel is 10mm/min, walking number of times is 10 times.Vacuum in degassing procedure in vacuum electron beam zone melting furnace is 9 × 10-4Pa。
Step 4, zone refining.Melting is carried out by area electron beam smelting furnace to the iridium rod after degasification.Existed by melting Melting zone is produced in iridium rod, and the melting zone lower surface is apart from the lower surface 50mm of iridium rod.Zone-melting technological parameter is：Electronics Rifle power be 1.1~1.2KW, main high tension voltage be 16KV, electron beam current be 0.07~0.08A, filament voltage be 3.8~ 4.0V, heater current is 58~60A.
After stablizing after melting zone, iridium rod rotation button is opened, iridium rod is rotated with 1~2r/min speed, is made described molten Area produces flowing, plays stirring action.
During the iridium rod rotation 2min, melting zone is tended towards stability again；Start electron gun to walk from bottom to top.Electron gun is distinguished With 15mm/min, 5mm/min and 3mm/min each walking once.Every time after walking, iridium rod melting zone forms the stable growth of iridium Region；The test piece of stable growth district under each speed of travel is cut respectively
The test piece of stable growth district, as speed of travel 3mm/min, is obtained under each speed of travel described in Metallographic Analysis Test piece have 1 crystal grain.
The specific mistake that the electron gun is respectively walked once with 15mm/min, 5mm/min and 3mm/min speed of travel respectively Cheng Shi：
The first step, electron gun is walked for the first time：The electron gun first time speed of travel is 15mm/min.Electron gun is from initial bit Put and walked upwards along the iridium rod surface by the speed of setting, the melting zone of the iridium rod is formed the stable growth district of iridium.Walking knot Shu Hou, the test piece when the stable growth district of the iridium rod cuts the speed of travel for 15mm/min.
Second step, second of walking of electron gun：1 will have been cut#The iridium rod welding of test piece.Electricity is passed through to the iridium rod after welding Beamlet zone melting furnace carries out melting.In fusion process, melting zone is produced at iridium rod lower surface 50mm in iridium rod.Treat that melting zone can stablize Afterwards, iridium rod rotation button is opened, iridium rod is rotated with 1~2r/min rotating speed.In the rotation of iridium rod, start electron gun with 5mm/ Min speed, carries out walking for second upwards from initial position along the iridium rod surface.After walking terminates, make the melting zone of the iridium rod Form the stable growth district of iridium.Test piece when the stable growth district of the iridium rod cuts the speed of travel for 5mm/min.
3rd step, electron gun third time is walked：2 will have been cut#The iridium rod welding of test piece.After repeatedly in second step to welding Iridium rod carry out melting and electron gun third time walking process.Start electron gun with 5mm/min speed, should from initial position edge Iridium rod surface upwards, with 3mm/min speed, third time walking is carried out along the iridium rod surface upwards.After walking terminates, make the iridium The melting zone of rod forms the stable growth district of iridium.Examination when the stable growth district of the iridium rod cuts the speed of travel for 3mm/min Piece.
Lower surface 50mm of the initial position away from iridium rod during electron gun walking, final position when electron gun is walked away from From iridium rod upper surface 50mm.
1 described in Metallographic Analysis#~3#Test piece, as speed of travel 3mm/min, obtained test piece has 1 crystal grain.
Step 5, detect.
Tested after being surface-treated to the obtained test piece for having 1 crystal grain, (001) side is oriented to selected by detection To (001) direction is with being axially displaced from angle φ=12.74 °, it was demonstrated that the sample is monocrystalline.
Metal iridium density reaches 22.42g/cm3, it is the maximum metal of density, by (γ/ρ g)1/2Understand, the density of metal iridium Larger, surface tension is smaller, and melting zone maintenance stable state is difficult, so the present invention needs to find suitable experiment parameter, i.e., it is electric Beamlet monitor system, vacuum, bar diameter, solidification drawing velocity, rotary speed and its mode are to metal iridium crystal growth Influence, the process parameters range for determining preparation high-quality iridium monocrystalline.
The present invention is big for iridium density, the problem of zone length control is more difficult, on the premise of theoretical parameter is instructed, profit Iridium monocrystalline is prepared with electron beam floating zone technique.
The present invention is by reasonably control electric current parameter, and melting zone is maintained at original charge bar and solidifying material by surface tension Between rod, and the directional solidification when electron gun is slowly moved along its length, so as to be given birth to along the length direction of whole charge bar It is grown to monocrystalline.And can the key that grow up to monocrystalline be electron gun walking speed V, i.e. directional solidification rates.V pairs of speed of walking The stabilization in melting zone, Crystal Growth Mechanism influence is larger, and vital effect is played to crystal growth.In oriented growth process In, when the speed of growth is slower, during crystal grain is grown up after forming core, crystal grain has time enough to be at war with growth, competition The crystal grain consistent with direction of heat flow is fully grown up in growth course, and the crystal grain inconsistent with direction of heat flow is then eliminated；And work as When growth rate is very fast, in growth process of the crystal after forming core, crystal grain does not have time enough to grow up just to be frozen into solidification group Knit, it is then highly difficult to grow up to monocrystalline.In the present invention, when the speed of travel of electron gun is 15mm/min, sample is 8 crystalline substances Grain, as polycrystalline, are shown in Fig. 2.When the speed of travel of electron gun is 5mm/min, sample is twin crystal, sees Fig. 3.When the row of electron gun When walking speed for 3mm/min, in metallograph shown in Fig. 4, sample has no crystal boundary, and it is monocrystalline tentatively to learn it.So growth When speed is slow, competitive growth is obvious in the effect for suppressing some directions of growth and the inconsistent crystal of direction of heat flow, after growth Grain structure is thicker, and number of die is less, until as monocrystalline.Experimental result is agreed with theory.Entered with RO-XRD and Laue method When one step is detected, it is monocrystal really to verify it.Therefore the present invention successfully obtains iridium monocrystalline.
To make the testing result of the present invention more convincing, the present invention is detected again using Laue method.With 1 crystal grain Test piece on choose 1# points and 2# points, the direction of point is [001], as shown in Figure 6.Obtained according to cos α=cos γ * cos δ, 1# Point deviates 12.8 °, and 2# points deviate 12.9 °, and this is basically identical with 12.7 ° of RO-XRD acquired results, it can be verified that sample is really to be single It is brilliant.
In summary, the present invention successfully prepares iridium monocrystalline, and preparation process has repeatability, i.e., in identical condition Under, repeatedly prepare and succeed.
Brief description of the drawings
Fig. 1 is electro-beam floating zone domain Principle of Melting figure.
When Fig. 2 is that the speed of travel of electron gun is 15mm/min, the tissue metallograph of the molten gained iridium sample in area, from figure It can be seen that sample is polycrystalline.
When Fig. 3 is that the speed of travel of electron gun is 5mm/min, the tissue metallograph of the molten gained iridium sample in area, it can be seen that Sample is twin crystal.
When Fig. 4 is that the speed of travel of electron gun is 3mm/min, the tissue metallograph of the molten gained iridium sample in area, it can be seen that Without crystal boundary in sample, it is monocrystalline tentatively to show it.
Fig. 5 is the RO-XRD diffraction patterns of monocrystalline sample.
Fig. 6 is the analysis chart that Laue method detects monocrystalline sample, and two points are chosen during detection, wherein, 6a, 6b are first point Diffraction pattern figure, it is 12.8 ° with the axial angle of sample to detect [100] orientation.6c, 6d are the diffraction pattern figure of second point, institute It is 12.9 ° with the axial angle of sample to detect [100] orientation.
Fig. 7 is the flow chart of the present invention.
In figure：1. anode iridium rod；2. cathode filament；3. electron beam；4. melting zone；5. seed crystal.
Embodiment
The present embodiment is that one kind uses equipment for vacuum electron beam zone melting furnace, utilizes electro-beam floating zone domain melting technique system The method of standby rare precious metal iridium monocrystalline.Detailed process is：
Step 1, iridium rod is corrected.The a diameter of Φ 6mm of iridium rod, long 300mm, electron gun are annular, and iridium rod is placed vertically In the annular circle centre position of electron gun；The initial position of electron gun is located at away from iridium rod lower surface 50mm.Electron gun is advanced when area is molten Direction is from bottom to top.The feed balance in iridium rod linearity influence melting zone, so require linearity≤1mm/m of the iridium rod.Will Iridium rod clamps correction with vice repeatedly, until meeting condition.Iridium rod surface has new impurity after correction, uses 1500# sand paper Polish for several times, untill it can not visually see impurity.Use alcohol washes.
Plus electric current step 2,.The upper grip of iridium rod clamping clamping device in vacuum electron beam zone melting furnace after the correction Between lower chuck；Order during clamping is first：Lower chuck is tightened, then upper grip is tightened in movement.It is clear with dust catcher after fixation Manage furnace chamber.Alcohol washes seal ring for furnace lid and electron gun gun body.If the quartz glass plating of the observation window of vacuum electron beam zone melting furnace There is metal, with removal of gently being polished with 2000# sand paper after alcohol-pickled 3min.Close area electron beam smelting furnace；ON cycle is cooled down Water；It is evacuated to higher than 1 × 10-3Stream is begun to power up after Pa.
The parameter of the electric current has two, is heater current and main high pressure respectively.
The heater current is risen using 20A → 30A → 40A staged, every 2min plus 10A, i.e., when the filament Electric current adds to 20A, stops 2min；Within dwell time 2min, keep current value constant.Powered up again after 2min and flow to 30A, then stopped 2min simultaneously keeps current value constant；Continue heater current adding to 40A after 2min.
Start when heater current is stabilized to after 40A to area electron beam smelting furnace plus main high pressure.The main high pressure still uses rank Ladder type pressuring method：Main high pressure adds to 16KV from 0, and the main high pressure often increases 1KV and stops 1min therebetween, i.e., when main high pressure is from 0 Stop 1min when adding to 1KV；Keep main high-voltage value constant within the 1min of stopping.Continue to stop 1min when adding 2KV after 1min And keep main high-voltage value constant；So often 1KV is added to stop 1min, until the main high pressure adds to 16KV.
Step 3, degasification.Containing gas and volatile impurity in iridium rod, the gas separated out in degassing procedure is miscellaneous with volatilization Matter can be attached to around cathode filament, cause the change of the internal resistance of source, and high-voltage breakdown causes electric discharge in stove when serious.Therefore, removing Gas process follows condition of high vacuum degree, quick multiple, principle from outward appearance to inner essence.Condition of high vacuum degree causes gas and volatile impurity from metal The speed of middle spilling is accelerated；Electron gun translational speed is fast, and the probability of electrion and interrupt experiments reduces, it is ensured that degassing procedure connects It is continuous to carry out.It is more thorough that electron gun movement repeatedly ensures that impurity is removed；From outward appearance to inner essence, successively removal of impurities, is conducive to the company of degassing procedure It is continuous to carry out.
Using ring-type electron gun degasification；The sub- rifle runs to upper end for once from iridium rod lower end.
Vacuum is set in degassing procedure as 9 × 10-4Pa.The electron gun speed of travel is 10mm/min, and walking number of times is 10 It is secondary, i.e., quick multiple principle.Because electron gun is annular, iridium rod is located at the circle centre position of annular, so iridium rod surface can be equal Even heating, is often walked once, heater current increase 0.5A, when at the 9th, 10 times, melting zone temperature close to fusing point, enable iridium rod by Table and in carry out degasification.
Step 4, zone refining.Melting is carried out by area electron beam smelting furnace to the iridium rod after degasification.In fusion process, Melting zone is produced at iridium rod lower surface 50mm in iridium rod.
After stablizing after melting zone, i.e., when melting zone can be stable in the presence of the middle part of the iridium rod by surface tension, open iridium rod Rotation button, makes iridium rod start rotation；Rotary speed is 1~2r/min.When iridium rod rotates, flowing is produced to the melting zone, risen To stirring action, and the temperature field of radial direction is more uniform.
During the iridium rod rotation 2min, melting zone is tended towards stability again；Start electron gun to walk from bottom to top.Electron gun is distinguished With 15mm/min, 5mm/min and 3mm/min speed of travel, respectively walking once, that is, carries out once independent experiment.Walking every time Afterwards, iridium rod melting zone surface is smooth, size uniform, represents that the iridium in the melting zone can be stablized and grows, forms the stable growth of iridium Region.Using conventional method in the stable growth district sampling detection.Detailed process is：
The first step, electron gun is walked for the first time：The electron gun first time speed of travel is 15mm/min.The initial bit of electron gun Put the lower surface 50mm away from iridium rod.Electron gun by setting speed from the initial position along the iridium rod surface run upwards to away from Stop from iridium rod upper surface 50mm, the melting zone of the iridium rod is formed the stable growth district of iridium.After walking terminates, described steady Determine growth district cuts Φ 6mm × 2mm 1#Test piece.
Second step, second of walking of electron gun：1 will have been cut#The iridium rod welding of test piece.Electricity is passed through to the iridium rod after welding Beamlet zone melting furnace carries out melting.In fusion process, melting zone is being produced at iridium rod lower surface 50mm.After stablizing after melting zone, Iridium rod rotation button is opened, iridium rod is rotated with 1~2r/min rotating speed.In the rotation of iridium rod, start electron gun with 5mm/min's The speed of travel carries out walking for second upwards along the iridium rod surface.Before second is walked, the initial position of electron gun is away from iridium rod Lower surface 50mm.Electron gun is run upwards to apart from iridium rod upper end by the speed of setting from the initial position along the iridium rod surface Stop at the 50mm of face, the melting zone of the iridium rod is formed the stable growth district of iridium.After walking terminates, Φ is cut in the iridium rod melting zone The 2 of 6mm × 2mm#Test piece.
3rd step, electron gun third time is walked：2 will have been cut#The iridium rod welding of test piece.Repeat butt welding in the second step Iridium rod after connecing carries out melting and electron gun third time walking process.The speed of electron gun third time walking is 3mm/min.3rd Before secondary walking, lower surface 50mm of the initial position away from iridium rod of electron gun.Electron gun is by the speed of setting from the initial position Run upwards to and stop at iridium rod upper surface 50mm along the iridium rod surface, the melting zone of the iridium rod is formed the stable growth of iridium Region.After walking terminates, the 3 of Φ 6mm × 2mm is cut in the iridium rod melting zone#Test piece.
It can cause the change of filament internal resistance because metallic vapour is attached on filament, cause the fluctuation of beam power, institute It is not unalterable with electric parameter, but electric current, when current is excessive, melting zone is adjusted in time with the change of melting zone state Become big and produce constriction, melting zone may be caused to cave in, now need to reduce electric current to maintain melting zone stable；When electric current is too small, not Melting zone can be formed, needs high current to produce melting zone.Melting electric parameter in the present embodiment is as follows：
Electron gun power KW 1.1~1.2
Main high tension voltage KV 16
Electron beam current A 0.07~0.08
Filament voltage V 3.8~4.0
Heater current A 58~60
Step 5, detect.
Metallographic Analysis is carried out to obtained each test piece, result is：When the speed of travel is 15mm/min, 1 obtained#Test piece There are 8 crystal grain；When the speed of travel is 5mm/min, 2 obtained#Test piece has 2 crystal grain；When the speed of travel is 3mm/min, 3 obtained#Test piece has 1 crystal grain.
To obtain 3#Test piece is polished, and is polishing to after no marking uses using 800,1000,1500,2000 sand paper successively 0.5 granularity antiscuffing paste is polished, until no marking, obtains the iridium metallographic specimen of flakelet.Configure HF：HCL=1:1 corrosion Liquid, by the iridium metallographic specimen electrolytic etching, etching time is 40~60min.
After corrosion terminates, the iridium metallographic specimen of no crystal boundary is selected, the sample is further tested, using RO-XRD methods, [001] direction is oriented to selected by detection, [001] direction is with being axially displaced from angle φ=12.74 °, it was demonstrated that the sample is monocrystalline.

Claims (5)

1. a kind of method for preparing iridium monocrystalline, it is characterised in that detailed process is：
Step 1, the correction and surface treatment of iridium rod；
Plus heater current and main high pressure step 2,：
Iridium rod clamping after the correction is in vacuum electron beam zone melting furnace between the upper grip and lower chuck of clamping device；Alcohol Clean seal ring for furnace lid and electron gun gun body；Close area electron beam smelting furnace；ON cycle cooling water；It is evacuated to higher than 1 × 10- 3Stream and main high pressure are begun to power up after Pa；
Step 3, degasification：
By ring-type electron gun, the degasification by the way of quickly repeatedly walking：The electron gun speed of travel is 10mm/min, walking time Number is 10 times；Vacuum in degassing procedure in vacuum electron beam zone melting furnace is 9 × 10-4Pa；
Step 4, zone refining：
Melting is carried out by area electron beam smelting furnace to the iridium rod after degasification；Melting zone is produced in iridium rod by melting, and Lower surface 50mm of the melting zone lower surface apart from iridium rod；Zone-melting technological parameter is：Electron gun power is 1.1~1.2KW, Main high tension voltage be 16KV, electron beam current be 0.07~0.08A, filament voltage be 3.8~4.0V, heater current be 58~ 60A；
After stablizing after melting zone, iridium rod rotation button is opened, iridium rod is rotated with 1~2r/min speed, is produced from the melting zone Raw flowing, plays stirring action；
During the iridium rod rotation 2min, melting zone is tended towards stability again；Start electron gun to walk from bottom to top；Electron gun respectively with 15mm/min, 5mm/min and 3mm/min each walking are once；Every time after walking, iridium rod melting zone forms the stable vitellarium of iridium Domain；The test piece of stable growth district under each speed of travel is cut respectively；
The test piece of stable growth district under each speed of travel described in Metallographic Analysis, as speed of travel 3mm/min, obtained examination Piece has 1 crystal grain；
Step 5, detect：
Tested after being surface-treated to the obtained test piece for having 1 crystal grain, (001) direction be oriented to selected by detection, (001) direction is with being axially displaced from angle φ=12.74 °, it was demonstrated that the sample is monocrystalline.
2. the method for preparing iridium monocrystalline as claimed in claim 1, it is characterised in that the linearity of the iridium rod after the correction≤ 1mm/m。
3. the method for preparing iridium monocrystalline as claimed in claim 1, it is characterised in that during described plus heater current, using 20A → 30A → 40A staged rises, and every 2min plus 10A, i.e., when the heater current adds to 20A, stops 2min；Dwell time Within 2min, keep filament current value constant；Add heater current after 2min again to 30A, then stop 2min and keep the heater current Value is constant；Continue heater current adding to 40A after 2min；
Start when heater current is stabilized to after 40A to area electron beam smelting furnace plus main high pressure；
Described plus main high pressure uses staged pressuring method：Main high pressure adds to 16KV from 0, and the main high pressure often increases 1KV i.e. therebetween Stop 1min, i.e., stop 1min when main high pressure adds to 1KV from 0；Keep main high-voltage value constant within the 1min of stopping；1min Continue to add afterwards and stop 1min during 2KV and keep main high-voltage value constant；So often 1KV is added to stop 1min, until the main high pressure is added to 16KV。
4. the method for preparing iridium monocrystalline as claimed in claim 1, it is characterised in that step 4 electron gun is respectively with 15mm/ Respectively the detailed process of walking once is min, 5mm/min and 3mm/min speed of travel：
The first step, electron gun is walked for the first time：The electron gun first time speed of travel is 15mm/min；Electron gun is pressed from initial position The speed of setting is walked upwards along the iridium rod surface, the melting zone of the iridium rod is formed the stable growth district of iridium；After walking terminates, Test piece when the stable growth district of the iridium rod cuts the speed of travel for 15mm/min；
Second step, second of walking of electron gun：1 will have been cut#The iridium rod welding of test piece；Electron beam is passed through to the iridium rod after welding Zone melting furnace carries out melting；In fusion process, melting zone is produced at iridium rod lower surface 50mm in iridium rod；After stablizing after melting zone, Iridium rod rotation button is opened, iridium rod is rotated with 1~2r/min rotating speed；In the rotation of iridium rod, start electron gun with 5mm/min's Speed, carries out walking for second upwards from initial position along the iridium rod surface；After walking terminates, the melting zone of the iridium rod is set to form iridium Stable growth district；Test piece when the stable growth district of the iridium rod cuts the speed of travel for 5mm/min；
3rd step, electron gun third time is walked：2 will have been cut#The iridium rod welding of test piece；Repeat in second step to the iridium after welding Rod carries out melting and electron gun third time walking process；Start electron gun with 5mm/min speed, from initial position along the iridium rod Surface upwards, with 3mm/min speed, third time walking is carried out along the iridium rod surface upwards；After walking terminates, make the iridium rod Melting zone forms the stable growth district of iridium；Test piece when the stable growth district of the iridium rod cuts the speed of travel for 3mm/min.
5. the method for preparing iridium monocrystalline as claimed in claim 4, it is characterised in that initial position during electron gun walking away from The lower surface 50mm of iridium rod, final position when electron gun is walked is apart from iridium rod upper surface 50mm.
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Publication number Priority date Publication date Assignee Title
CN104959604A (en) * 2015-07-23 2015-10-07 华中科技大学 High energy beam area-selecting fusing method and device capable of controlling temperature gradient in shaping area
CN104975194A (en) * 2015-07-20 2015-10-14 中国工程物理研究院材料研究所 High-purity uranium metal preparing device and method
CN106381519A (en) * 2016-09-27 2017-02-08 西北有色金属研究院 Method for controlling equal-diameter growth of large-size molybdenum-niobium alloy single crystal bar

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104975194A (en) * 2015-07-20 2015-10-14 中国工程物理研究院材料研究所 High-purity uranium metal preparing device and method
CN104959604A (en) * 2015-07-23 2015-10-07 华中科技大学 High energy beam area-selecting fusing method and device capable of controlling temperature gradient in shaping area
CN106381519A (en) * 2016-09-27 2017-02-08 西北有色金属研究院 Method for controlling equal-diameter growth of large-size molybdenum-niobium alloy single crystal bar

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