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TKD (transmission Kikuchi diffraction)-based determining method for stress state of single grain of polycrystalline material

A polycrystalline material and stress state technology, which is applied in the material analysis using radiation diffraction, etc., can solve the problems that the stress state of the crystal grains cannot be determined, and the microscopic driving force cannot be known.

Inactive Publication Date: 2019-01-04
INST OF METAL RESEARCH - CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The usual EBSD technology can give the change of crystal orientation, the generation of twins, and the difficulty of deformation (Schmidt factor) when the material is deformed by a macroscopic external force, but EBSD is the result of a large number of grain statistics. Moreover, it can only reflect the deformation of grains under macroscopic external force. The actual macroscopic external force acts on the sample, and the actual stress state of a certain grain inside the sample cannot be determined.
TEM technology can go deep into the atomic scale, and can give specific dislocations and twin structures, but the microscopic driving force of these dislocations and twins cannot be known, so many results based on TEM technology analysis of deformation mechanisms can only give A possible deformation mechanism cannot be combined with external forces
[0003] In the prior art, there is no report on the stress state of a single grain inside a polycrystalline material. If a method for determining the stress state of a single grain inside a polycrystalline material can be found, all deformation behaviors of this grain can be used stress state

Method used

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  • TKD (transmission Kikuchi diffraction)-based determining method for stress state of single grain of polycrystalline material
  • TKD (transmission Kikuchi diffraction)-based determining method for stress state of single grain of polycrystalline material
  • TKD (transmission Kikuchi diffraction)-based determining method for stress state of single grain of polycrystalline material

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0037] Zr-4 alloy, whose nominal composition is Zr-1.5Sn-0.2Fe-0.1Cr, has excellent corrosion resistance and is widely used as cladding material for pressurized water reactors and heavy water reactors.

[0038] A Zr-4 alloy plate with a thickness of 4 mm has an average diameter of equiaxed α grains at room temperature of about 8 μm, and its microstructure is as follows: figure 2shown. After the alloy plate is sheared and deformed (please refer to the patent with publication number CN107044941A for the specific method), a thin slice sample is taken in the deformation zone, pre-ground to a thickness of 60 μm, and then punched (with a diameter of Ф3 mm), and the sample is ground again. The thickness is reduced to 40 μm, and finally double-jet electrolysis is used to reduce the thickness again. The electrolytic polishing solution adopts 10% perchloric acid and 90% alcohol by volume. With this, transmission sample preparation ends.

[0039] Using a transmission electron microsco...

Embodiment 2

[0046] A 45# steel bar with a diameter of 8mm. After the alloy undergoes compression deformation, the amount of compression deformation is 5%. Take a thin slice sample in the deformation zone, pre-grind to a thickness of 60 μm, then punch a hole (diameter Ф3mm), grind again, and thin the sample to 40 μm, and finally double-jet electrolysis thins again, and the volume fraction of the electrolytic polishing solution is 10 % perchloric acid and 90% alcohol. With this, transmission sample preparation ends.

[0047] as attached Figure 8 As shown, the dislocation densities in the three grains at the edge of the hole in the transmission sample have an order of magnitude difference, as indicated by the arrows in the figure. Grain 1 (hereinafter referred to as grain 1) has the highest dislocation density, followed by Grain 2 (hereinafter referred to as grain 2), and Grain 3 (hereinafter referred to as grain 3) basically has no dislocation contrast inside the grain, that is, the gra...

Embodiment 3

[0052] A pure copper TU0 plate with a thickness of 5mm. After the alloy sheet is stretched and deformed, a thin slice sample is taken in the deformed area, pre-ground to a thickness of 60 μm, then punched (diameter Ф3mm), ground again, and the sample is thinned to 40 μm, and finally thinned again by double-jet electrolysis . With this, transmission sample preparation ends.

[0053] as attached Figure 11 As shown, in the STEM mode, it is observed that the dislocation densities in the three grains differ by orders of magnitude, as indicated by the arrows in the figure. The dislocation densities inside Grain 2 (hereinafter referred to as grain 2) and Grain 3 (hereinafter referred to as grain 3) are basically the same, and the dislocation density inside Grain 1 (hereinafter referred to as grain 1) is significantly lower than that of grain 2 and grain 3. According to the dislocation densities inside the three grains, it can be inferred that grain 2 and grain 3 are in soft orie...

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Abstract

The invention aims to provide a TKD (transmission Kikuchi diffraction)-based determining method for stress state of a single grain of a polycrystalline material. The method is characterized by comprising the following steps: the to-be-studied single grain is determined firstly, whether dislocation density of the grain and several surrounding grains has order-of-magnitude difference is determined,if the density has order-of-magnitude difference, further analysis can be performed, and a slip system open in the grains is determined; then specific orientation distribution of the grains is obtained by adopting the TKD analysis technology; the slip system is input into a Schmid factor calculation part of an HKL Channel 5 system, the macroscopic stress direction is adjusted simultaneously, an obtained Schmid factor value is enabled to be consistent with a predicted result, then the macroscopic force is the stress direction of the grains and is also the stress direction of the single grain. The method is applicable to any crystalline material, the specific stress state of the single grain in the material in a deformation process can be calculated well, and one definite and effective method is provided for studying the microscopic deformation mechanism of the polycrystalline material.

Description

technical field [0001] The invention relates to the field of research on the microscopic deformation mechanism of materials, and in particular provides a TKD determination method for the stress state of a single crystal grain of a polycrystalline material. Background technique [0002] All metal components will be subjected to various loads during plastic processing and later service, and these loads will cause deformations such as slippage or twinning of the grains inside the metal components. In the prior art, the research on the deformation behavior and deformation mechanism of polycrystalline metal materials is mainly divided into two directions: macroscopic research and microscopic research: macroscopic research mainly focuses on the force on the material under macroscopic conditions, such as the rolling force of the plate rolling process , the tensile force during the stretching process of the sample and the compressive force during compression, etc.; the main research...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N23/20
CPCG01N23/20
Inventor 李阁平袁福森刘承泽韩福洲张英东穆罕默德·阿里郭文斌顾恒飞
Owner INST OF METAL RESEARCH - CHINESE ACAD OF SCI
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