A method for preparing micro-nano copper by multi-directional compression torsion composite extrusion

Abstract

The invention discloses a method for preparing micro-nano copper through multi-axial compression, twisting and combined extrusion. The method comprises the following steps: (1) carrying out softening pre-treatment on a copper ingot blank; (2) carrying out multi-axial compression circulating extrusion on the blank obtained by the step (1) to generate great plastic deformation of the blank; fining the size of a crystal grain to obtain a sub-micron grade; (3) carrying out rounding treatment on the blank obtained by the step (2) to obtain a designed blank shape size; (4) carrying out destressing annealing treatment on the blank obtained by the step (3); (5) carrying out movable concave die twisting and extrusion on the blank obtained by the step (4), so as to generate multi-grade forward extrusion and compression neck deformation of the blank, and fining the size of the crystal grain to obtain a micro-nano grade; (6) carrying out microstructure sampling analysis on the blank obtained by the step (5) so as to guarantee tissue performance of the prepared micro-nano copper. The method provided by the invention can be applied to preparation of ultrafine crystals including pure copper, brass, white brass and the like and micro-nano materials.

Description

technical field [0001] The invention relates to a method for preparing micronano copper by multidirectional compression torsion composite extrusion. Background technique [0002] Micro-nano copper and copper alloys are an important direction for the development of advanced material technology. The grain size of micro-nano copper and copper alloy is ultra-fine, and has some physical and mechanical properties different from conventional materials. The traditional grain size refinement is mainly through the large forging ratio deformation of high-precision forging equipment and high-frequency forging to open the billet, so as to promote the breakage and refinement of grains, and inhibit the growth of grains, but the grain size is generally in the order of hundreds of microns. It is difficult to refine the grain size to submicron or even micronano level. At present, there are two main methods for the preparation of micro-nano copper and copper alloys. One is the bottom-up meth...

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Problems solved by technology

The traditional grain size refinement is mainly through the large forging ratio deformation of high-precision forging equipment and high-frequency forging to open the billet, so as to promote the breakage and refinement of grains, and inhibit the growth of grains, but the grain size is generally in the order of hundreds of microns. It is difficult to refine the grain size to submicron or even micronano

At present, there are two main methods for the preparation of micro-nano copper and copper alloys. One is the bottom-up method, that is, the ultra-fine powder is prepared by physical, chemical or mechanical methods, and then the powder is sintered and densified. and other methods to prepare micro-nano copper blanks, but the cost of this method is high, and there are inevitably residual pores and powder impurities, and the prepared micro-nano copper has small specifications; the second is the top-down method, that is, directly on the block Severe plastic deformation processing of shaped copper and copper alloys, such as equal-diameter angular extrusion, cumulative stack rolling, high-pressure torsion, etc. Relevant scholars at home and abroad have carried out basic theoretical research using small samples, and prepared micro-nano-scale copper and copper alloys. Copper alloy, but the hydrostatic pressure of the material in the deformation zone of this method is very small, mainly due to shear strain, and microscopic defects cannot be effectively closed and repaired. Some ultra-fine-grained materials have high strength and poor plasticity, and most of them are in the micro-nano copper and copper alloy small sample preparation stage, has not been effective engineering application

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