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Gradient metal material with coarse grains on surface layer and nano grains or ultra-fine grains inside and preparing method

A metal material and nanocrystalline technology, applied in the field of gradient materials, can solve the problems of strength reduction, weakening the strength of nanocrystalline or ultrafine grained materials, etc., to achieve the effect of improving plasticity, realizing large-scale industrial production, and good combination of strength and toughness

Active Publication Date: 2019-08-27
WUHAN UNIV OF TECH
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

In the various existing heterogeneous structures, the grain size is spatially gradient, and the gradient metal material that continuously increases from the surface nanocrystalline or ultrafine grain size to the internal coarse grain size can improve the plasticity to close to the coarse grain plasticity, and the strength-plasticity point is also above the strength-plasticity inversion curve; however, compared with the corresponding nanocrystalline or ultrafine-grained materials, the strength of this gradient material drops a lot: the yield strength drops to the corresponding 0.2-0.5 times the yield strength of fine-grained materials, and the tensile strength drops to 0.4-0.6 times the tensile strength of corresponding nanocrystalline or ultra-fine-grained materials [T.H.Fang, et al., Science 311(2011) 1587; X.Wu , et al., Proceedings of the National Academy of Sciences 111(2014) 7197], which weakens the advantages of extremely high strength of nanocrystalline or ultrafine crystalline materials

Method used

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  • Gradient metal material with coarse grains on surface layer and nano grains or ultra-fine grains inside and preparing method
  • Gradient metal material with coarse grains on surface layer and nano grains or ultra-fine grains inside and preparing method
  • Gradient metal material with coarse grains on surface layer and nano grains or ultra-fine grains inside and preparing method

Examples

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Effect test

Embodiment 1

[0034] This embodiment provides a round rod-shaped gradient Cu with a diameter of Φ4mm, and the grain size is reduced from the surface average grain size of 1 μm to 800nm ​​at a radius of 0.75 from the center, 650nm at a radius of 0.5 from the center, and 650nm at a distance from the center in a continuous gradient manner. 500nm at the 0.25 radius of the center, 400nm at the center.

[0035] The above-mentioned circular bar-shaped gradient Cu is prepared according to the following steps. First, the precursor ultra-fine-grained Cu with uniform grain size distribution was prepared by multi-directional compression by severe plastic deformation method: the coarse-grained Cu was processed into a shape suitable for multi-directional compression mold by wire electric discharge cutting, and six passes were carried out at room temperature times of multi-directional compression processing. The hardness of the material after multi-directional compression is 145HV. Through the analysis of ...

Embodiment 2

[0037] This embodiment provides a square rod-shaped gradient 5083Al with a cross-sectional size of 15 mm × 15 mm. The grain size decreases from the average grain size of the surface layer to about 3 μm in a continuous gradient manner to an average grain size of 300 nm at a distance of 4.5 mm from the surface, and then from there The average grain size remained at about 300 nm in the core (ie, 7.5 mm from the surface).

[0038] The above-mentioned square rod gradient 5083Al is prepared according to the following steps. First, the precursor ultra-fine-grained 5083Al with uniform grain size distribution was prepared by the severe plastic deformation method by equal-channel angular extrusion: the coarse-grained 5083Al was processed into a shape suitable for the equal-channel angular extrusion die by wire electric discharge cutting, and it was processed at 200 Eight passes of equal channel angular extrusion were performed at ℃. The hardness of the material after equal channel angu...

Embodiment 3

[0040] This embodiment provides a plate-shaped gradient equiatomic ratio high-entropy alloy FeCoCrNi with a thickness of 4 mm, and the grain size is reduced from the average grain size of the surface layer to about 1.2 μm in a continuous gradient manner to an average grain size of 95 nm at a distance of 1.5 mm from the surface. , and then from here to the core (ie, 2 mm from the surface) the average grain size remains at about 95 nm.

[0041] The above-mentioned plate-shaped gradient high-entropy alloy FeCoCrNi is prepared according to the following steps. First, a 45 mm thick equiatomic ratio high-entropy alloy FeCoCrNi plate was rolled to a final thickness of 4 mm at room temperature, that is, the thickness reduction was about 91%. Through the observation of transmission electron microscope, it can be seen that in the high-entropy alloy FeCoCrNi rolled at room temperature to a thickness reduction of 91%, the grain size is uniformly distributed in space, and the average grain...

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Abstract

The invention relates to a gradient metal material with coarse grains on a surface layer and nano grains or ultra-fine grains inside and a preparing method. According to the gradient metal material with the coarse grains on the surface layer and the nano grains or ultra-fine grains inside, the grain size is reduced to 10 to 100 nm of the interior nano gains or 100 to 1000 nm of the ultra-fine grains from the 1 to 100 micrometers of the coarse grains on the surface layer in a continuous gradient manner. The preparing method comprises the steps that a precursor nano grains or ultra-fine grain metal material which is prepared through severe plastic deforming or solidification nano grains or nanoscale powder and has the grain size space distribution uniformity is subjected to induction heatingtreatment; the gradient metal material has the enough toughness and meanwhile keeps the nano grain or ultra-fine grain metal material strength to be maximum degree, and the preparing method is simple, and easy to implement; and large-scale industrial production is easily achieved.

Description

technical field [0001] The invention relates to the field of gradient materials, in particular to a gradient metal material with coarse grains on the surface and inner nanocrystals or ultrafine grains and a preparation method thereof. Background technique [0002] Due to the needs of machinery manufacturing, national defense industry, construction, shipbuilding and ocean engineering, high-performance advanced metal materials have always been an important development direction in the field of material science. Nanocrystalline or ultrafine-crystalline metal materials are prepared for extremely high strength. attention. The strength of nanocrystalline or ultrafine-grained materials can be several times that of coarse-grained materials, but compared with coarse-grained materials, the plasticity is poor, especially the uniform elongation is very low, the so-called strength-plasticity inversion relationship. Designing a multi-scale heterogeneous structure containing nanocrystals ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22F1/08C22F1/04C22F1/16
CPCC22F1/04C22F1/08C22F1/16
Inventor 林耀军贾兴祺
Owner WUHAN UNIV OF TECH