Method for characterizing purity of hafnium-containing high-temperature alloy

Abstract

The invention belongs to the technical field of alloy detection, and relates to a hafnium-containing high-temperature alloy purity characterization method. The characterization method comprises the following steps: (1) carrying out electron beam melting on a weighed hafnium-containing high-temperature alloy sample under a vacuum condition; and (2) after the hafnium-containing high-temperature alloy sample is solidified, detecting and analyzing a floating inclusion accumulation area of the hafnium-containing high-temperature alloy sample so as to evaluate the purity of the hafnium-containing high-temperature alloy. According to the method for characterizing the purity of the hafnium-containing high-temperature alloy, hafnium oxide can fully and completely float upwards in the electron beam smelting process of the hafnium-containing high-temperature alloy, so that the characterization result of the purity of the hafnium-containing high-temperature alloy is more accurate and reliable.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of alloy detection and relates to a purity characterization method for a hafnium-containing high-temperature alloy. BACKGROUND

[0002] Hafnium oxide is one of the common harmful impurities in the hafnium-containing high-temperature alloy. At present, the verification method for the purity of the batch-produced high-temperature alloy in China is the dross method, which is verified according to HB 5406-2016 “Casting High-Temperature Alloy Ingot Dross Test Method”. However, due to the fact that the important inclusions hafnium oxide in the hafnium-containing high-temperature alloy has a density greater than that of the nickel-based high-temperature alloy liquid and is irregularly distributed in the high-temperature alloy, it is difficult to control the floating, which often leads to inaccurate characterization results of the purity of the hafnium-containing high-temperature alloy ingot after smelting. In addition, the removal effect of hafnium oxide is an important acceptance index for the purity of the hafnium-containing high-temperature alloy, but the traditional dross method cannot be used for verification.

[0003] The electron beam smelting method can be used for purifying metals and characterizing the purity of high-temperature alloys. In the prior art, the electron beam cold bed method is used to purify high-temperature alloys, hafnium oxide is precipitated at the bottom, and impurities such as aluminum oxide and magnesium oxide float up. After removing the bottom and the upper part, the purification purpose is achieved. However, this method cannot characterize the specific content of hafnium oxide in the high-temperature alloy and is only suitable for purifying high-temperature alloys.

[0004] For example, in the article “Evaluation of FGH4097 Purity by Electron Beam Button Melting” (Xia Fukuan. [D]. Dalian University of Technology, 2024. DOI:10.26991 / d.cnki.gdllu.2024.005214.), a circular truncated cone type water-cooled copper crucible is used in combination with low-power long-time smelting to achieve the purpose of floating of inclusions in the alloy. However, this method can only make inclusions such as aluminum oxide and magnesium oxide with a density lower than that of the high-temperature alloy float up, and cannot promote the floating of hafnium oxide.

[0005] For another example, in the article “Metallurgical Behavior and High-Temperature Properties of Ultra-Pure DZ125 Alloy Prepared by Electron Beam Refining” (Li Yi. [D]. Dalian University of Technology, 2024. DOI:10.26991 / d.cnki.gdllu.2024.000272.), the results on page 71 show that when the improved electron beam method is used to prepare DZ125 alloy, hafnium oxide is enriched in the area 20 μm away from the top of the ingot, and there is still some hafnium oxide in the bottom area. Therefore, this method can be used for purifying and removing hafnium oxide in DZ125 alloy, but cannot quantitatively characterize the hafnium oxide in DZ125 alloy.

[0006] 2024. DOI:10.26991 / d.cnki.gdllu.2024.000272.) shows that when the improved electron beam method is used to prepare DZ125 alloy, hafnium oxide is enriched in the area 20 μm away from the top of the ingot, and there is still some hafnium oxide in the bottom area. Therefore, this method can be used for purifying and removing hafnium oxide in DZ125 alloy, but cannot quantitatively characterize the hafnium oxide in DZ125 alloy. SUMMARY

[0007] The object of the present application is to provide a purity characterization method for hafnium-containing superalloys, so that the hafnium-containing superalloys can be fully and completely floated in the electron beam melting process of the hafnium-containing superalloys, thereby making the purity characterization results of the hafnium-containing superalloys more accurate and reliable.

[0008] To achieve this object, in a basic embodiment, the present application provides a purity characterization method for hafnium-containing superalloys, which comprises the following steps:

[0009] (1) Electron beam melting of the weighed hafnium-containing superalloy sample under vacuum conditions;

[0010] (2) After the hafnium-containing superalloy sample solidifies, the floating inclusion aggregation zone thereof is detected and analyzed to evaluate the purity of the hafnium-containing superalloy.

[0011] In a preferred embodiment, the present application provides a purity characterization method for hafnium-containing superalloys, wherein the hafnium-containing superalloy is selected from cast hafnium-containing superalloy ingots, powder hafnium-containing superalloy ingots, deformed hafnium-containing superalloy ingots, hafnium-containing superalloy castings, or hafnium-containing superalloy forgings.

[0012] In a preferred embodiment, the present application provides a purity characterization method for hafnium-containing superalloys, wherein the hafnium-containing superalloy sample is pretreated before electron beam melting, and the pretreatment comprises grinding or turning the surface oxide, removing visible refractory material, sticky iron, slag inclusions, and honeycomb defects, and / or cleaning the surface of the hafnium-containing superalloy sample with a silk cloth dipped in alcohol.

[0013] In a preferred embodiment, the present application provides a purity characterization method for hafnium-containing superalloys, wherein in step (1), the absolute pressure of the vacuum condition is ≤0.1 Pa.

[0014] In a preferred embodiment, the present application provides a purity characterization method for hafnium-containing superalloys, wherein in step (1), the electron beam melting is performed by placing the hafnium-containing superalloy sample in a water-cooled copper crucible, and then placing the water-cooled copper crucible in an electron beam button furnace for electron beam melting.

[0015] In a preferred embodiment, the present application provides a purity characterization method for hafnium-containing superalloys, wherein in step (1), the water-cooled copper crucible is cleaned before the hafnium-containing superalloy sample is loaded, and the cleaning is performed by cleaning the inner wall of the water-cooled copper crucible with a silk cloth dipped in alcohol to make the inner wall present the copper color, and / or grinding the inner wall of the water-cooled copper crucible to the copper color with a tool.

[0016] In a preferred embodiment, the present application provides a purity characterization method of hafnium-containing superalloy, wherein in step (1), during electron beam melting,

[0017] The preheating is performed by circular wave scanning with a scanning radius of 30-60 mm.

[0018] The sample melting process is performed by circular wave scanning, spiral wave scanning and / or linear scanning, the electron gun scanning radius is 5-55 mm, and the melting power is 10-30 kw (the corresponding current is preferably 1-3 A).

[0019] After the hafnium-containing superalloy sample is completely refined, the power is kept unchanged, and the refining is performed by raster scanning and / or circular wave scanning, the electron gun scanning radius is 25-55 mm, the current is 0.5-2.5 A, and the refining time is 0.5-5 min.

[0020] After the refining is completed, the current is adjusted to 0.5-1.8 A, and the scanning radius is gradually reduced within 3-150 s until the alloy liquid with dross is completely solidified.

[0021] In a preferred embodiment, the present application provides a purity characterization method of hafnium-containing superalloy, wherein in step (2), the detection analysis includes photographing and image analysis, the hafnium-containing superalloy sample after photographing is analyzed by image analysis software to obtain the projection area F of the inclusion aggregation area in the horizontal direction when the hafnium-containing superalloy sample is horizontally placed, and further calculate the purity level C of the hafnium-containing superalloy sample according to the ratio of F to the weight G of the hafnium-containing superalloy sample. EB .

[0022] In a preferred embodiment, the present application provides a purity characterization method of hafnium-containing superalloy, wherein in step (2), the detection analysis includes qualitative analysis of inclusion type by energy spectrometer, and / or observation of inclusion morphology by scanning electron microscope, and / or determination of inclusion size by image analysis software after photographing.

[0023] In a preferred embodiment, the present application provides a purity characterization method of hafnium-containing superalloy, wherein in step (2), before or after the detection analysis, the solidified hafnium-containing superalloy sample is also visually inspected to confirm that the surface is free of obvious oxidation and unmelted defects.

[0024] The present application has the beneficial effect that by using the purity characterization method of hafnium-containing superalloy, the sufficient and complete floating of hafnium oxide during electron beam melting of the hafnium-containing superalloy can be achieved, so that the purity characterization result of the hafnium-containing superalloy is more accurate and reliable.

[0025] The prior art, whether adopting dross method (for example, according to HB 5406-2016 “Foundry High-temperature Alloy Ingot Dross Test Method”) or electron beam melting method (for example, according to the article “Evaluation of FGH4097 Purity by Electron Beam Button Melting”), when evaluating the purity of high-temperature alloy containing hafnium, only impurities such as aluminum oxide and magnesium oxide can float to the surface of the alloy liquid, and hafnium oxide cannot float to the surface of the alloy liquid, resulting in inaccurate purity evaluation results. The present application can make hafnium oxide fully and completely float during the electron beam melting process of high-temperature alloy containing hafnium, so that the purity characterization results of high-temperature alloy containing hafnium are more accurate and reliable. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 Flow chart of the purity characterization method of the high-temperature alloy containing hafnium of the present application, which is exemplary in the specific embodiment.

[0027] Figure 2 Principle diagram of the device structure of the purity characterization method of the high-temperature alloy containing hafnium of the present application, which is exemplary in the specific embodiment, including an electron gun 1 and a water-cooled copper crucible 2.

[0028] Figure 3 Schematic diagram of the button ingot sampling method of the purity characterization method of the high-temperature alloy containing hafnium of the present application, which is exemplary in the specific embodiment, wherein a is a top view and a schematic diagram of inclusion aggregation area; b is a side view and a schematic diagram of sampling position.

[0029] Figure 4 Low-magnification scanning electron microscope detection morphology diagram of the upper heart inclusion of the DZ125 alloy button ingot in Example 1, wherein the red area is the inclusion.

[0030] Figure 5 High-magnification scanning electron microscope detection morphology diagram of the upper heart inclusion of the DZ125 alloy button ingot in Example 1, wherein a is 200 times; b is 500 times; and c is 1000 times.

[0031] Figure 6 Energy spectrum EDS analysis results of the upper heart inclusion of the DZ125 alloy button ingot in Example 1, wherein a is the analysis results of the white contrast area; and b is the analysis results of the black contrast area.

[0032] Figure 7 Sampling detection results diagram of the center part of the DZ125 alloy button ingot in Example 1, wherein a is a schematic diagram of the sampling position; b is a high-magnification (100 times) scanning electron microscope detection morphology diagram; and c is an energy spectrum EDS analysis results diagram of the white contrast area.

[0033] Figure 8Figure of detection result of lower heart sampling of DZ125 alloy button ingot in example 1, wherein a is schematic diagram of sampling position; b is high magnification (100 times) detection morphology diagram of scanning electron microscope; c is analysis result diagram of white contrast area energy spectrum EDS.

[0034] Figure 9 Figure of low magnification detection morphology diagram of upper heart inclusion of DZ125 alloy button ingot in comparative example 1, wherein red area is inclusion.

[0035] Figure 10 Figure of high magnification detection morphology diagram of upper heart inclusion of DZ125 alloy button ingot in comparative example 1, wherein a is 200 times; b is 500 times; c is 1000 times.

[0036] Figure 11 Figure of EDS analysis result of upper heart inclusion of DZ125 alloy button ingot in comparative example 1, wherein a is analysis result of black contrast area; b is analysis result of white contrast area.

[0037] Figure 12 Figure of detection result of lower heart sampling of DZ125 alloy button ingot in comparative example 1, wherein a is schematic diagram of sampling position; b is high magnification (100 times) detection morphology diagram of scanning electron microscope; c is analysis result diagram of white contrast area energy spectrum EDS. DETAILED DESCRIPTION

[0038] The flow of the exemplary purity characterization method of the hafnium-containing high-temperature alloy of the application is shown in Figure 1 The device structure principle is shown in Figure 2 The method comprises the following steps:

[0039] Step one, preparation before experiment: the surface oxide of the hafnium-containing high-temperature alloy sample is polished or turned, there is no visual refractory material, sticky iron, slag inclusion and honeycomb defect, the sample surface is cleaned by silk cloth dipped with alcohol; the inner wall of the water-cooled copper crucible is cleaned by silk cloth dipped with alcohol before smelting, so that the inner wall is copper color, if the alcohol cannot be cleaned completely, the tool is used to polish the inner wall of the water-cooled copper crucible to copper color, and the cleaning is completed;

[0040] Step two, weighing: the weight of the hafnium-containing high-temperature alloy sample is weighed by an electronic scale, and is recorded;

[0041] Step three, sample loading: the hafnium-containing high-temperature alloy sample is loaded into the water-cooled copper crucible and put into the electron beam button furnace to close the furnace door;

[0042] Step four, smelting: the vacuum system of the electron beam button furnace is started, vacuum is pumped, the absolute pressure in the furnace should be less than or equal to 0.1 Pa, and the pressure in the electron gun chamber should be less than 1×10 -3Pa, open the electron gun isolation valve, start the electron gun to smelt; using a circular wave scanning with a scanning radius of 30-60mm to preheat for 5-15min; using circular wave scanning, spiral wave scanning and / or linear scanning during the sample melting process, the electron gun scanning radius is 5-55mm, the smelting power is 10-30kw, the corresponding current is 1-3A, manual fine tuning of scanning parameters can be performed during the process to ensure that the sample is completely melted; after the hafnium-containing high-temperature alloy sample is completely melted, the power is kept unchanged, and raster scanning and / or circular wave scanning is used for refining, the electron gun scanning radius is 25-55mm, the current is 0.5-2.5A, and the refining time is 0.5-5min; after refining, the current is adjusted to 0.5-1.8A, and the scanning radius is gradually reduced (retraction) within 3-150s, until the alloy liquid with dross is completely solidified;

[0043] Step five, cooling: after the smelting solidification process is completed, continue to vacuumize to keep the absolute pressure in the furnace less than or equal to 0.1Pa, for 60-120min, and after the sample is completely cooled, the vacuum system is closed;

[0044] Step six, photographing: after the water-cooled copper crucible is rotated to the photographing position, the computer photographing program (for example, using a Japan TAMRON camera with a model of M112FM50 and its self-provided program to take pictures on the computer) is opened, and the horizontally placed button ingot that has completed solidification in the crucible is photographed. If the horizontal projection area of the dross is too small and the resolution of the camera is not enough, the button ingot is taken out and photographed using a stereoscopic mirror or a scanning electron microscope.

[0045] Step seven, inspection: the cooled button ingot is taken out, and the surface is visually inspected. There should be no obvious oxidation or unmelted defects. The surface of the button ingot is not allowed to be polished, polished or pickled.

[0046] The specific inspection items and methods are as follows:

[0047] (1) Quantitative analysis of purity level

[0048] The button ingot picture after photographing is analyzed by image analysis software (such as Photo shop, Imagin pro plus). The software automatically calculates the projected area value (cm 2 or (mm 2 ) of the inclusions gathered in the center. If the horizontal projection area of the sample inclusions is smaller than the range that can be distinguished by the camera above the smelting chamber, the horizontal projection area of the inclusions can be measured by means of a scanning electron microscope and image analysis software (together with the qualitative analysis below). The purity level C EB of the alloy is calculated according to the measured projected area of the inclusions:

[0049] C EB= F / G … … (1)

[0050] In the formula:

[0051] C EB : purity level of the sample, unit: cm 2 / kg or mm 2 / g;

[0052] F: the projected area of the surface inclusion level of the button ingot in the horizontal direction, unit: cm 2 or mm 2 ;

[0053] G: the weight of the button ingot, unit: kg or gram g;

[0054] (2) qualitative analysis

[0055] Put the button ingot sample (see sampling method in Figure 3 ) into a scanning electron microscope (such as Zeiss Sigma300, equipped with AZTEC spectrum and image analysis software; or Thermo Apero 2C, equipped with AZTEC spectrum and image analysis software) with a spectrum analyzer and image analysis software to observe the inclusion morphology of different sampling sites, qualitatively analyze the inclusion type (oxide: alumina, silica, magnesium oxide; sulfide; nitride or other types of inclusions) by the spectrum analyzer; at the same time, determine the size of the inclusion, including area, equivalent diameter, etc. by the image analysis software.

[0056] The requirements and principles of the above exemplary purity characterization method of hafnium-containing high-temperature alloy of the present application are as follows:

[0057] 1. Requirements for equipment and samples

[0058] (1) The electron beam button furnace should be equipped with a hemispherical water-cooled copper crucible with a diameter of 60-100 mm. The absolute pressure should be no more than 0.1 Pa, and the maximum melting power should be no less than 30 kW. The electron gun scanning modes include but are not limited to the following four: raster scanning, circular wave scanning, spiral wave scanning, and linear scanning.

[0059] (2) The electron beam button furnace should be equipped with a high-definition camera with a pixel of no less than 2 million. The camera is connected to a computer and is equipped with image analysis software with area calculation function.

[0060] (3) A scanning electron microscope is required for inclusion analysis and detection, which should be equipped with:

[0061] a) Sample stage: computer control, X-Y direction motor drive, preferably using an automatic sample stage;

[0062] b) Energy spectrum analyzer: the resolution shall meet the requirements of GB / T17359, and the electron beam and sample stage can be controlled according to the set parameters, images and graphs can be collected, and inclusion chemical composition analysis can be performed;

[0063] c) Backscattered electron detector: one or more threshold values can be set to distinguish the matrix and inclusions;

[0064] d) Image acquisition software: images can be collected;

[0065] e) Image analysis software, which can calculate the area of dross, with the following requirements:

[0066] 1) The analysis conditions can be set for chemical classification, and the inclusions can be classified according to element composition, size and morphological characteristics;

[0067] 2) The equivalent diameter and area size of single inclusion can be measured, and the statistical function can be provided to count the inclusion content or area of different element characteristics.

[0068] (4) Calibration and verification of equipment:

[0069] The radiation of the electron beam button furnace shall meet the requirements of GB18871.

[0070] The magnification of the scanning electron microscope shall be calibrated and verified according to GB / T27788 periodically.

[0071] The energy spectrum analyzer shall be calibrated according to the provisions of GB / T17359.

[0072] The energy resolution of the energy spectrum analyzer shall be verified periodically according to GB / T17359.

[0073] The maximum weighing weight of the electronic scale shall not be less than 1000g, and the weighing accuracy shall be ±0.1g.

[0074] (5) The sample is a hafnium-containing high-temperature alloy purity sample. When there is no special provision, a hafnium-containing high-temperature alloy ingot can be taken at will, and the sample is cut from the upper part of the alloy ingot, i.e. the last pouring part. The maximum size of the sample shall not be greater than 100mm, which is also the diameter of the electron beam button furnace crucible, and the weight is 200-400g.

[0075] 2. Principles and precautions

[0076] The electron beam melting equipment, such as the electron beam button furnace, is a special melting equipment for high-temperature refractory metals, which is a high-temperature melting furnace using the kinetic energy of high-speed electron beam current into heat energy as a heat source. Through manual or automatic control of the melting and solidification process, the purification of the metal is completed. In the melting stage, the foreign inclusions float to the surface of the molten liquid, and the solidification process is controlled to make the inclusions concentrate in the center of the button. Finally, a cluster is formed in the center of the button. By combining high-resolution cameras and image analysis software, the inclusions in the alloy can be quantitatively characterized.

[0077] The electron beam melting equipment uses electron beam bombardment under ultra-high vacuum to complete the remelting of the sample. By continuously reducing the electron beam bombardment radius, the alloy gradually solidifies from the outside to the inside, and finally the inclusions are gathered in the core area. A high-definition camera is arranged above the melting chamber to take pictures of the solidified button ingot. Image analysis software can automatically test the area of inclusions in the picture, and the specific value of the inclusion area (mm 2 ) can be obtained.

[0078] The stability of the vacuum system is the prerequisite for the normal opening of the electron beam melting equipment. Before starting the furnace, the air leakage test should be carried out. After starting, the absolute pressure in the furnace should be less than or equal to 0.1 Pa, and the electron gun chamber should be less than 1 x 10 -3 Pa before opening the electron gun isolation valve. After starting the electron gun, the sample is completely melted, and the power is maintained for refining. After refining, the scanning radius is gradually reduced and the power is slowly reduced until the alloy liquid with dross is completely solidified.

[0079] The current acceptance standard for the purity of high-temperature alloy master alloy is HB 5406-2016 "Casting High-Temperature Alloy Ingot Dross Test Method". This method uses dross calculation software to obtain the result as an area percentage (%). The result obtained by this method is an area mass percentage (cm 2 / kg).

[0080] The above example of the application of the hafnium-containing high-temperature alloy purity characterization method of the present application and the verification example is as follows.

[0081] Example 1: Hafnium-containing high-temperature alloy purity characterization (I)

[0082] Take a DZ125 alloy ingot (containing hafnium) and cut a sample of about 300g from the upper part. The purity of the sample is characterized according to the following method steps.

[0083] Step one, preparation before experiment: the surface oxide of the hafnium-containing high-temperature alloy sample is polished or turned, no visible refractory material, sticky iron, slag inclusion and honeycomb defect, the sample surface is cleaned with silk cloth dipped in alcohol; the inner wall of the water-cooled copper crucible is cleaned with silk cloth dipped in alcohol before smelting, so that the inner wall is copper in color, if it cannot be cleaned with alcohol, the tool is used to polish the inner wall of the water-cooled copper crucible to copper color, and it is cleaned.

[0084] Step two, weighing: the weight of the hafnium-containing high-temperature alloy sample is weighed by an electronic scale, and the weight is recorded, the sample weight is 305g.

[0085] Step three, sample loading: the hafnium-containing high-temperature alloy sample is loaded into the water-cooled copper crucible (crucible diameter 70mm), and put into the electron beam button furnace and close the furnace door.

[0086] Step four, smelting: start the vacuum system of the electron beam button furnace, vacuumize, the absolute pressure in the furnace should be less than or equal to 0.1Pa, the pressure in the electron gun chamber is less than 1×10 -3 Pa, open the electron gun isolation valve, start the electron gun for smelting; preheat for 10min by circular wave scanning with scanning radius of 40mm; the sample melting process adopts spiral wave scanning, the electron gun scanning radius is 15mm, the smelting power is 14kw, the current is 1.5A, the manual fine tuning of scanning parameters can be carried out in this process to ensure that the sample is completely melted; after the hafnium-containing high-temperature alloy sample is completely melted, the power is kept unchanged, the raster scanning is used for refining, the electron gun scanning radius is 40mm, the current is 1.5A, and the refining time is 1min; after refining, the current is adjusted to 1.8A, and the scanning radius is gradually reduced (retraction) within 30s, until the alloy liquid with dross is completely solidified.

[0087] Step five, cooling: after the smelting and solidification process is completed, continue to vacuumize to keep the absolute pressure in the furnace less than or equal to 0.1Pa for 90min, and then close the vacuum system after the sample is completely cooled.

[0088] Step six, photographing: after the water-cooled copper crucible is rotated to the photographing position, the photographing program of the computer is opened (the photographing of the computer is carried out by using the camera of Japan TAMRON, model M112FM50 and the self-provided program), and the horizontally placed button ingot in the crucible which has been completely solidified is photographed, and since the area of the dross is too small, the button ingot is taken out and photographed by means of the body mirror.

[0089] Step seven, inspection: the cooled button ingot is taken out, and the surface is visually inspected, there is no obvious oxidation, unmelted defect, and the surface of the button ingot has not been polished, polished or pickled.

[0090] The photographing effect of step six is as follows: Figure 4The SEM morphology observation result of the inclusion aggregation area (upper core) of the button ingot core is shown in 2 , the EDS analysis result of the white contrast area is shown in EB , and the EDS analysis result of the black contrast area is shown in 2 .

[0091] The SEM morphology observation result of the inclusion aggregation area (upper core) of the button ingot core is shown in Figure 5 , the EDS analysis result of the white contrast area is shown in Figure 6 , and the EDS analysis result of the black contrast area is shown in Figure 6 . Therefore, in combination with Figure 5 and Figure 6 , it is shown that Figure 5 the white contrast area in the center is hafnium oxide, and the black contrast area is aluminum oxide.

[0092] Further dissection of the button ingot core, 10mmx10mmx10mm cubes were cut from the middle part of the center (core part) and the lower part of the center (lower core part) for high-magnification scanning electron microscopy observation and EDS analysis, and the results are shown in Figure 7 and Figure 8 , which show that there is no inclusion in the middle part of the center and the lower part of the center under 100 times magnification (the white contrast material in the figure is tantalum-rich carbide (TaC), which is a strengthening phase in the alloy, and the rest is the alloy matrix), thus showing that the hafnium oxide in the button ingot does not sink.

[0093] Comparative Example 1: Purity characterization of hafnium-containing high-temperature alloy (two)

[0094] This comparative example characterizes the purity of the upper sample of the same DZ125 alloy ingot as in Example 1, but differs from Example 1 in the following aspects.

[0095] Step two, weighing: the sample weight is 295g.

[0096] Step four, melting: the sample melting process adopts circular wave scanning, the electron gun scanning radius is 58mm, and the current is 5A; after the hafnium-containing high-temperature alloy sample is completely melted, the power is kept unchanged, circular wave scanning is adopted for refining, the electron gun scanning radius is 56mm, the current is 3.5A, and the refining time is 5min; after refining, the current is adjusted to 0.4A, and the scanning radius is gradually reduced (retraction) within 100s, until the alloy liquid with scum is completely solidified.

[0097] The photographing effect of step six is shown in Figure 9 , and the inclusion area is 283473μm 2 calculated by image analysis software, thus EB C=0.00096mm2 g, much less than C of the same part of the same alloy ingot of Example 1 EB The calculation results.

[0098] The scanning electron microscope morphology observation results of the inclusion aggregation area (upper core) of the button ingot center floating up are shown in Figure 10 , wherein the energy spectrum EDS analysis results of the black contrast area are shown in Figure 11 , and the energy spectrum EDS analysis results of the white contrast area are shown in Figure 11 . Therefore, in combination with Figure 10 and Figure 11 , it is shown that Figure 10 the areas in the red frames are mainly aluminum oxide, and do not contain hafnium oxide.

[0099] Further dissection of the button ingot inside, 10mm×10mm×10mm cubic blocks are cut from the lower part of the center (lower core) for high-magnification scanning electron microscope observation and energy spectrum EDS analysis, and the results are shown in Figure 12 , which shows that there are a large number of hafnium oxide sediments in the lower part of the button ingot center under 100 times magnification field of view, which failed to float up, which affected the evaluation results of the purity of the alloy.

[0100] Obviously, those skilled in the art can make various modifications and variations to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application also intends to include these modifications and variations. The above examples or embodiments are only illustrative of the present application, and the present application can also be implemented in other specific ways or other specific forms without departing from the spirit or essential characteristics of the present application. Therefore, the described embodiments should be considered illustrative rather than limiting in any aspect. The scope of the present application should be illustrated by the appended claims, and any changes equivalent to the intent and scope of the claims should also be included in the scope of the present application.

Claims

1. A method for characterizing the purity of hafnium-containing superalloys, characterized in that, The characterization method includes the following steps: (1) The weighed hafnium-containing high-temperature alloy sample was subjected to electron beam melting under vacuum conditions; (2) After the hafnium-containing high-temperature alloy sample solidifies, the area where the inclusions on the surface accumulates is detected and analyzed to evaluate the purity of the hafnium-containing high-temperature alloy.

2. The characterization method according to claim 1, characterized in that: The hafnium-containing high-temperature alloy is selected from cast hafnium-containing high-temperature alloy ingots, powdered hafnium-containing high-temperature alloy ingots, wrought hafnium-containing high-temperature alloy ingots, hafnium-containing high-temperature alloy castings, or hafnium-containing high-temperature alloy forgings.

3. The characterization method according to claim 1, characterized in that: The hafnium-containing high-temperature alloy sample undergoes pretreatment before electron beam melting. The pretreatment includes grinding or turning the surface oxides to remove any visible refractory materials, stuck iron, slag inclusions, and honeycomb defects, and / or cleaning the surface of the hafnium-containing high-temperature alloy sample with a silk cloth soaked in alcohol.

4. The characterization method according to claim 1, characterized in that: In step (1), the absolute pressure of the vacuum condition is ≤0.1 Pa.

5. The characterization method according to claim 1, characterized in that: In step (1), the electron beam melting involves placing the hafnium-containing high-temperature alloy sample in a water-cooled copper crucible, and then placing the water-cooled copper crucible in an electron beam button furnace for electron beam melting.

6. The characterization method according to claim 5, characterized in that: In step (1), the water-cooled copper crucible is cleaned before the hafnium-containing high-temperature alloy sample is placed in it. The cleaning is done by cleaning the inner wall of the water-cooled copper crucible with a cloth soaked in alcohol to make the inner wall show the copper color, and / or by polishing the inner wall of the water-cooled copper crucible with a tool until the copper color is revealed.

7. The characterization method according to claim 5, characterized in that: In step (1), during electron beam melting, Preheating is performed using circular wave scanning with a scanning radius of 30-60 mm; The sample melting process employs circular wave scanning, spiral wave scanning, and / or linear scanning, with an electron gun scanning radius of 5-55 mm and a melting power of 10-30 kW. After all hafnium-containing high-temperature alloy samples were cleaned, the power was kept constant, and refining was carried out using grating scanning and / or circular wave scanning. The electron gun scanning radius was 25-55 mm, the current was 0.5-2.5 A, and the refining time was 0.5-5 min. After refining, adjust the current to 0.5-1.8A and gradually reduce the scanning radius over 3-150 seconds until the alloy liquid with slag completely solidifies.

8. The characterization method according to claim 1, characterized in that: In step (2), the detection and analysis includes taking pictures and image analysis. The hafnium-containing high-temperature alloy sample after being photographed is analyzed using image analysis software to obtain the projected area F of the inclusion accumulation area in the horizontal direction when the hafnium-containing high-temperature alloy sample is placed horizontally. Then, the purity level C of the hafnium-containing high-temperature alloy sample is calculated based on the ratio of F to the weight G of the hafnium-containing high-temperature alloy sample. EB .

9. The characterization method according to claim 1, characterized in that: In step (2), the detection and analysis includes qualitative analysis of the inclusion type by energy dispersive spectroscopy, and / or observation of the inclusion morphology by scanning electron microscopy, and / or determination of the inclusion size by image analysis software after taking a picture.

10. The characterization method according to claim 1, characterized in that: In step (2), before or after the detection and analysis, the solidified hafnium-containing high-temperature alloy sample is visually inspected to confirm that there are no obvious oxidation or unmelted defects on the surface.

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