Method and device for testing mechanical properties of interdendritic alloy liquid film

Abstract

The application discloses a kind of single crystal intergranular alloy liquid film mechanical characteristics testing method and device, it is related to force test technical field, and testing method includes cutting, polishing, obtains single wafer, etching and cleaning, spraying, assembly and test and so on Step, the upper die and lower die of device respectively threadedly matched to the bottom end of upper connecting bolt and the top end of lower connecting bolt with single wafer being arranged, the end face of both is opened coaxial communication through-hole, alloy sheet is arranged in through-hole.The application replaces single wafer with the primary structure grain in alloy microstructure in alloy solidification later period, constructs basic unit sample like " primary structure-liquid film-primary structure", and then realizes the test of liquid film mechanical characteristics between two single grains based on the basic unit sample, realizes the research of alloy hot crack characteristic and hot crack mechanism from microcosmic level, and it has important significance to eliminate alloy hot crack defect, provides theoretical basis for practical application of alloy.

Description

Technical Field

[0001] This invention relates to the field of hot cracking research, and more specifically to a method and testing apparatus for studying the mechanical properties of an alloy liquid film between two single grains in hot cracking research. Background Technology

[0002] Hot cracking is a serious defect that occurs during alloy solidification. Its presence not only reduces production yield, hindering efficiency and cost control, but also negatively impacts the mechanical properties of parts, sometimes even rendering them unusable. Hot cracks can be categorized into external and internal cracks. External cracks are located on the surface of the part and can usually be observed with the naked eye; internal cracks are located inside the part and require instrumental detection. Compared to external cracks, internal cracks are more dangerous.

[0003] Modern research indicates that hot cracking occurs in the later stages of alloy solidification. During this stage, the alloy's microstructure consists of solidified grains surrounded by a liquid film, exhibiting relatively low strength and ductility. When the workpiece experiences stress due to restricted shrinkage, this stress acts on the liquid film. When the stress exceeds the liquid film's bearing capacity, the film ruptures, forming microcracks. Therefore, research on the mechanical properties and fracture mechanisms of intergranular liquid films is of great significance for eliminating hot cracking defects.

[0004] Existing hot cracking research techniques rely on studying the tensile properties of polycrystalline alloy samples under high-temperature conditions to indirectly infer the stress variation and fracture mechanism of the alloy liquid film. However, due to the varying sizes of polycrystalline grains, the different thicknesses of the intergranular liquid film, and the complex coupling effects, it is difficult to accurately study the microscopic mechanism of hot cracking caused by stress on the liquid film between grains. The method and testing apparatus of this invention directly measure the stress variation of the alloy liquid film between two single grains to further clarify the hot cracking formation mechanism. Summary of the Invention

[0005] To avoid the shortcomings of the prior art, the present invention provides a method and apparatus for testing the mechanical properties of alloy liquid films between single grains.

[0006] To solve the technical problem, this invention adopts the following technical solution: a method for testing the mechanical properties of an alloy liquid film between single grains, comprising the following steps:

[0007] The first step is cutting.

[0008] Cut the alloy material into alloy sheets of a specified diameter and thickness;

[0009] The second step is to polish the alloy sheet obtained in the first step to remove the oxide film on the surface of the alloy sheet and make the surface of the alloy sheet flat.

[0010] The third step is to obtain a single-crystal wafer.

[0011] two single crystal wafers with specified diameters are commercially available;

[0012] Fourth step, etching and cleaning

[0013] The single crystal wafers are etched to remove the oxide film using corresponding chemical solvents, and then cleaned with anhydrous ethanol;

[0014] Fifth step, spraying

[0015] The upper and lower molds for installing the alloy piece are sprayed with boron nitride paint on the surfaces in contact with the alloy piece and the contact surface between the upper and lower molds;

[0016] Sixth step, assembly

[0017] The two single crystal wafers are installed into the upper and lower molds respectively, and then the upper and lower molds are installed onto a high-temperature tensile testing machine, and the alloy piece is clamped between the two single crystal wafers;

[0018] Seventh step, testing

[0019] The temperature of the high-temperature tensile testing machine is heated to a temperature above the solidus of the alloy piece, and kept for a period of time, so that the alloy piece changes into liquid phase, and the liquid alloy piece and the single crystal wafers are metallurgically combined, then the temperature is reduced to the required temperature for tensile testing, and the tensile testing is performed.

[0020] Further, in the sixth step, when the alloy piece is clamped between the two single crystal wafers, the alloy piece is first placed into the through hole opened at the top end of the lower mold, and then the upper and lower molds are driven to close by the high-temperature tensile testing machine.

[0021] Further, the upper and lower molds are installed onto the high-temperature tensile testing machine through upper and lower connecting bolts respectively.

[0022] Further, the alloy material cut in the first step is eutectic alloy material, and the alloy piece is a eutectic composition alloy piece, and the surface oxide film of the eutectic composition alloy piece is removed during polishing in the second step.

[0023] The single crystal wafers commercially available in the third step are single crystal Si wafers, and the chemical solvent used in the fourth step is dilute HF.

[0024] A kind of single crystal intergranular alloy liquid film mechanical property testing device, including by upper and lower coaxial arrangement upper connecting bolt and lower connecting bolt, the upper connecting bolt and lower connecting bolt are the threaded end of both upper and lower ends are provided with double-end bolt;Upper die and lower die are respectively by top and bottom end opening threaded hole sleeve structure, respectively threadedly cooperated sleeve to the bottom end of the upper connecting bolt and the top end of lower connecting bolt, the end face of both is opened coaxial communication through-hole;The lower end surface of the upper connecting bolt and the upper die between and the lower end surface of the lower connecting bolt and the lower die between tight pad single crystal wafer, alloy sheet is provided in the through-hole.

[0025] Further, the lower end surface of the upper die and the upper end surface of the lower die are provided with grooves.

[0026] Further, the single crystal wafer and the lower end surface of the upper connecting bolt or the upper end surface of the lower connecting bolt are further provided with graphite paper.

[0027] Further, the diameter of the single crystal wafer is matched with the aperture of the threaded hole of the upper die and the lower die, and the diameter of the eutectic composition alloy sheet is matched with the diameter of the through-hole.

[0028] The present application provides a kind of single crystal intergranular alloy liquid film mechanical property testing method and device, with the following beneficial effects:

[0029] 1, the present application replaces single crystal wafer with primary structure grain in alloy microstructure in later stage of alloy solidification, constructs basic unit sample like " primary structure-liquid film-primary structure", and then realizes the test of liquid film mechanical property between two single crystal grains based on the basic unit sample, realizes the research of alloy hot cracking characteristic and hot cracking mechanism from microcosmic level, has important significance to eliminate the hot crack defects of alloy, provides theoretical basis for practical application of alloy;

[0030] 2, the bottom end of the upper die and the top end of the lower die of the present application are provided with grooves, and the grooves are used to accommodate the alloy sheet with volume increment when the alloy sheet is transformed into liquid phase, to avoid the outflow of liquid alloy sheet, and to ensure the safety and accuracy of the experiment;

[0031] 3, the present application has simple structure, convenient to use, can be suitable for intergranular liquid film mechanical property and fracture mechanism test of different materials, and can meet the experimental requirements of single crystal wafer and alloy sheet of different sizes and thicknesses, has good adaptability and practicality. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 It is the tensile force-tensile displacement curve of single crystal Si sheet and eutectic aluminum-silicon alloy liquid film in embodiment 1 of the present application;

[0033] Figure 2 It is the structural schematic diagram of the present application;

[0034] Figure 3 A-A is a schematic view of a partial cross-sectional structure of the present application.

[0035] In the figure:

[0036] 1, upper connecting bolt; 2, upper mold; 3, lower mold; 4, lower connecting bolt; 5, graphite paper; 6, groove; 7, single wafer; 8, alloy sheet; 9, through hole. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the embodiments of the present application. Obviously, the described embodiments are some embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0038] A testing method of mechanical properties of a single-grain inter-alloy liquid film, comprising the following steps:

[0039] First step, cutting

[0040] Cutting the alloy material into alloy sheets 8 with specified diameters and thicknesses;

[0041] Second step, polishing the alloy sheets 8 obtained in the first step to remove the oxide film on the surface of the alloy sheets 8 and make the surface of the alloy sheets 8 flat;

[0042] Third step, obtaining single wafers 7

[0043] Obtaining two single wafers 7 with specified diameters from the market;

[0044] Fourth step, etching and cleaning

[0045] Using corresponding chemical solvents to etch the single wafers 7 to remove the oxide film, and then cleaning the single wafers 7 with anhydrous ethanol;

[0046] Fifth step, spraying

[0047] Spraying boron nitride paint on the surfaces of the upper mold 2 and the lower mold 3 for contacting the alloy sheets 8 and the contact surface between the upper mold 2 and the lower mold 3, so as to prevent the alloy sheets 8 from being combined with the upper mold 2 or the lower mold 3 after phase transition into liquid phase;

[0048] Sixth step, assembling

[0049] Two single crystal wafers 7 are respectively installed into the upper die 2 and the lower die 3, and then the upper die 2 and the lower die 3 are installed onto the high-temperature tensile testing machine, and then the alloy sheet 8 is clamped and limited between the two single crystal wafers 7;

[0050] Step 7, testing

[0051] The temperature of the high-temperature tensile testing machine is heated to a temperature above the solidus of the alloy sheet 8, and the alloy sheet 8 is kept at the temperature for a period of time, so that the alloy sheet 8 is changed into liquid phase, and the liquid alloy sheet 8 is metallurgically combined with the single crystal wafers 7, and then the temperature is reduced to the temperature required for tensile testing, and the tensile testing is performed.

[0052] Preferably, in the sixth step, when the alloy sheet 8 is clamped and limited between the two single crystal wafers 7, the alloy sheet 8 is first placed into the through hole 9 opened at the top end of the lower die 3, and then the high-temperature tensile testing machine is controlled to drive the upper die 2 and the lower die 3 to be combined.

[0053] Preferably, the upper die 2 and the lower die 3 are respectively installed onto the high-temperature tensile testing machine through the upper connecting bolt 1 and the lower connecting bolt 4.

[0054] Preferably, the alloy material cut in the first step is eutectic alloy material, and the alloy sheet 8 is a eutectic composition alloy sheet, and the surface oxide film of the eutectic composition alloy sheet should be removed when it is polished in the second step.

[0055] The single crystal wafer 7 obtained in the third step is a single crystal Si wafer, and the chemical solvent used in the fourth step is dilute HF.

[0056] As shown in Figures 2-3 The structural relationship of a device for testing the mechanical properties of a liquid alloy film between single crystal grains is as follows: the upper connecting bolt 1 and the lower connecting bolt 4 are coaxially arranged from top to bottom, the upper connecting bolt 1 and the lower connecting bolt 4 are double-headed bolts with external threads at both ends, the top end of the upper connecting bolt 1 and the bottom end of the lower connecting bolt 4 are respectively connected to the two working ends of the high-temperature tensile testing machine; the upper die 2 and the lower die 3 are sleeve structures with threaded holes opened at the top end and the bottom end, respectively, and are threadedly fitted into the bottom end of the upper connecting bolt 1 and the top end of the lower connecting bolt 4, respectively, and the end faces of the two are coaxially connected through the through hole 9; the single crystal wafers 7 are clamped and limited between the lower end face of the upper connecting bolt 1 and the upper die 2 and between the upper end face of the lower connecting bolt 4 and the lower die 3; in actual use, the length of the upper connecting bolt 1 screwed into the upper die 2 and the length of the lower connecting bolt 4 screwed into the lower die 3 can be adjusted to adapt to the clamping and limiting of single crystal wafers 7 of different thicknesses; the alloy sheet 8 is arranged in the through hole 9; in actual use, the length of the through hole 9 can be adjusted by changing the depth of the threaded hole opened in the upper die 2 and the lower die 3, so as to adapt to eutectic composition alloy sheets 8 of different thicknesses.

[0057] Preferably, grooves 6 are provided on the lower end face of the upper mold 2 and the upper end face of the lower mold 3; after the eutectic alloy sheet 8 changes to a liquid phase, it may increase in volume due to the phase change. The grooves 6 can accommodate the increased volume of the liquid eutectic alloy sheet 8 when the liquid eutectic alloy sheet 8 experiences the aforementioned increase in volume.

[0058] Preferably, a graphite paper 5 is also pressed between the single crystal wafer 7 and the lower end face of the upper connecting bolt 1 or between the single crystal wafer 7 and the upper end face of the lower connecting bolt 4.

[0059] Preferably, the diameter of the single crystal wafer 7 matches the diameter of the threaded holes in the upper mold 2 and the lower mold 3, and the diameter of the eutectic alloy sheet 8 matches the diameter of the through hole 9.

[0060] In the later stage of alloy solidification, the microstructure of the alloy consists of primary structure and alloy liquid film distributed in between, forming a semi-solid structure with "primary structure-liquid film-primary structure" as the basic unit.

[0061] The above-mentioned method for studying the mechanical properties of alloy liquid film between individual grains involves sandwiching an alloy sheet 8 between two single-crystal wafers 7. After the alloy sheet 8 changes to a liquid phase, the basic unit sample of "primary structure-liquid film-primary structure" is constructed. Then, based on this basic unit sample, the mechanical properties of alloy liquid film between individual grains are tested.

[0062] Example 1

[0063] The fracture behavior of high-alumina silicon alloy liquid films was tested using the aforementioned methods and testing equipment for studying the mechanical properties of alloy liquid films between individual grains, including the following process:

[0064] The first step is cutting.

[0065] The eutectic aluminum-silicon alloy material Al-12.6wt.%Si was cut into circular pieces with a diameter of 8mm and a thickness of 1.3mm to obtain eutectic alloy sheet 8, which is made of eutectic aluminum-silicon alloy and is in the shape of a circular piece;

[0066] Here, the diameter of the eutectic alloy sheet 8 should match the diameter of the through hole 9 of the upper mold 2 and the lower mold 3;

[0067] The alloy material used here should have the same composition as the liquid film present in the final stage of solidification of the high-silicon aluminum alloy;

[0068] The second step is polishing.

[0069] The eutectic alloy sheet 8 obtained in the first step is polished to remove the oxide film;

[0070] The third step is to obtain a single-crystal Si wafer.

[0071] A single crystal Si wafer with a thickness of 250 μm and a diameter of 11.5 mm is commercially available as a single wafer 7;

[0072] Here, the diameter of the single wafer 7 should match the hole diameter of the threaded hole of the upper mold 2 and the lower mold 3;

[0073] The single wafer used here should be the same as the composition of the primary crystal grains of the high-silicon aluminum alloy;

[0074] Fourth step, etching and cleaning

[0075] The single wafer 7 is etched with dilute HF to remove the oxide film, and then the single wafer 7 is cleaned with anhydrous ethanol;

[0076] Fifth step, spraying

[0077] The contact surface of the upper mold 2 and the lower mold 3 and the contact surface of the upper mold 2 and the lower mold 3 and the eutectic composition alloy sheet 8 liquid film are sprayed with boron nitride paint to prevent the aluminum-silicon eutectic liquid from being combined with the upper mold 2 or the lower mold 3;

[0078] Sixth step, assembly

[0079] The two single wafers 7 and the two graphite papers 5 are sequentially placed into the threaded holes of the upper mold 2 and the threaded holes of the lower mold 3 from the top of the threaded holes of the upper mold 2 and the bottom of the threaded holes of the lower mold 3; then, the upper connecting bolt 1 and the lower connecting bolt 4 are respectively screwed into the threaded holes of the upper mold 2 and the threaded holes of the lower mold 3 from the top of the threaded holes of the upper mold 2 and the bottom of the threaded holes of the lower mold 3, so that the bottom end of the upper connecting bolt 1 and the top end of the lower connecting bolt 4 reach the preset position in the threaded holes; then the upper connecting bolt 1 and the lower connecting bolt 4 are installed on the high-temperature tensile testing machine, the alloy sheet 8 is placed into the through hole 9 of the lower mold 3, and the high-temperature tensile testing machine is controlled to drive the upper mold 2 and the lower mold 3 to close;

[0080] Seventh step, testing

[0081] The temperature on the high-temperature tensile testing machine is heated to a temperature above the eutectic line of the eutectic aluminum-silicon alloy material and held for a period of time, so that the eutectic composition alloy sheet 8 in the through hole 9 is transformed into a liquid phase, and the liquid phase eutectic composition alloy sheet 8 is metallurgically combined with the single wafer 7; then the temperature is lowered to 590°C, and the tensile test is performed;

[0082] The tensile force-displacement curve of the single crystal Si wafer and the eutectic aluminum-silicon alloy liquid film is as follows Figure 1 .

[0083] It is to be noted that, in the present text, relational terms such as first and second and the like can be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises", "comprising", or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can also include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by "comprises... a" does not, without more constraints, exclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element.

[0084] The above examples are merely used to illustrate the technical solutions of the present application, but not to limit it; although the present application has been described in detail with reference to the foregoing examples, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for testing the mechanical properties of an alloy liquid film between single grains, characterized in that, Includes the following steps: The first step is cutting. The alloy material is cut into alloy sheets (8) with a diameter of 8 mm and a thickness of 1.3 mm. The alloy material is a eutectic alloy material, and the alloy sheet (8) is a eutectic alloy sheet. The second step is to polish the alloy sheet (8) obtained in the first step to remove the oxide film on the surface of the alloy sheet (8) and make the surface of the alloy sheet (8) flat. The third step is to obtain a single-crystal wafer (7). Two single-crystal wafers with a diameter of 11.5 mm were purchased commercially (7); Step 4: Corrosion and Cleaning The single crystal wafer (7) is etched with a suitable chemical solvent to remove the oxide film, and then the single crystal wafer (7) is cleaned with anhydrous ethanol. Step 5, spraying Boron nitride coating is sprayed on the surfaces of the upper mold (2) and the lower mold (3) used to install the alloy sheet (8) that are in contact with the alloy sheet (8), as well as on the contact surfaces between the upper mold (2) and the lower mold (3). Step 6, Assembly The two single crystal wafers (7) are respectively installed into the upper mold (2) and the lower mold (3), and then the upper mold (2) and the lower mold (3) are installed on the high temperature tensile testing machine, and then the alloy sheet (8) is clamped between the two single crystal wafers (7); Step 7, Testing The temperature is heated to above the solidus line of the alloy sheet (8) on a high-temperature tensile tester and held for a period of time to make the alloy sheet (8) change into a liquid phase and to make the liquid phase alloy sheet (8) and the single crystal wafer (7) form a certain metallurgical bond. Then the temperature is lowered to the temperature required for the tensile test and the tensile test is performed.

2. The method for testing the mechanical properties of intergranular alloy liquid films according to claim 1, characterized in that: In the sixth step, when the alloy sheet (8) is clamped between two single crystal wafers (7), the alloy sheet (8) is first placed into the through hole (9) opened at the top of the lower mold (3), and then the high temperature tensile testing machine is controlled to drive the upper mold (2) and the lower mold (3) to close.

3. The method for testing the mechanical properties of intergranular alloy liquid films according to claim 1, characterized in that: The upper mold (2) and the lower mold (3) are respectively installed on the high temperature tensile testing machine by the upper connecting bolt (1) and the lower connecting bolt (4).

4. The method for testing the mechanical properties of intergranular alloy liquid films according to claim 1, characterized in that: In the second step, when polishing the eutectic alloy sheet, the oxide film on its surface should be removed. The single-crystal wafer (7) obtained commercially in the third step is a single-crystal Si wafer, and the chemical solvent used in the fourth step is dilute HF.

5. A testing apparatus for the mechanical properties of intergranular alloy liquid films, comprising testing the mechanical properties and fracture mechanism of intergranular liquid films using the testing method for the mechanical properties of intergranular alloy liquid films as described in claim 4, characterized in that: It includes an upper connecting bolt (1) and a lower connecting bolt (4) arranged coaxially from top to bottom. The upper connecting bolt (1) and the lower connecting bolt (4) are double-ended bolts with external threads at both ends. The upper mold (2) and the lower mold (3) are sleeve-shaped structures with threaded holes at the top and bottom ends, respectively. They are threadedly fitted onto the bottom end of the upper connecting bolt (1) and the top end of the lower connecting bolt (4). The end faces of the two are provided with coaxially connected through holes (9). A single crystal wafer (7) is pressed between the lower end face of the upper connecting bolt (1) and the upper mold (2) and between the upper end face of the lower connecting bolt (4) and the lower mold (3). An alloy sheet (8) is provided in the through hole (9).

6. The testing apparatus for the mechanical properties of intergranular alloy liquid films according to claim 5, characterized in that: The lower end face of the upper mold (2) and the upper end face of the lower mold (3) are provided with grooves (6).

7. The testing apparatus for the mechanical properties of inter-grain alloy liquid films according to claim 5, characterized in that: Graphite paper (5) is also pressed between the single crystal wafer (7) and the lower end face of the upper connecting bolt (1) or between the single crystal wafer (7) and the upper end face of the lower connecting bolt (4).

8. The testing apparatus for the mechanical properties of inter-grain alloy liquid films according to claim 5, characterized in that: The diameter of the single crystal wafer (7) matches the diameter of the threaded holes of the upper mold (2) and the lower mold (3), and the diameter of the eutectic alloy sheet (8) matches the diameter of the through hole (9).

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