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A nanocrystalline/ultrafine-crystalline biphasic bimodal bulk material and its preparation method

A technology of bulk materials and ultra-fine crystals, applied in the field of nanocrystalline iron-based bulk materials and their preparation, can solve the problems of sensitive parameters, difficult to repeat performance, high cost, etc., and achieve an easy-to-achieve effect

Inactive Publication Date: 2018-07-03
NORTHWESTERN POLYTECHNICAL UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] It is worth noting that the technology of Nanjing University of Science and Technology is sensitive to parameters, and the performance is not easy to repeat; the technology of D.Witkin and Taiyuan University of Technology involves complex chemical and physical processes, and the cost is high; the technology of Y.M.Wang and Tangshan University can only prepare single phase materials, there are limitations in industrial applications

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  • A nanocrystalline/ultrafine-crystalline biphasic bimodal bulk material and its preparation method
  • A nanocrystalline/ultrafine-crystalline biphasic bimodal bulk material and its preparation method
  • A nanocrystalline/ultrafine-crystalline biphasic bimodal bulk material and its preparation method

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preparation example Construction

[0030] combine figure 1 , the nanocrystalline / ultrafine-grained dual-phase bimodal iron-based bulk material and the preparation method thereof of the present invention utilize alloying, large plastic deformation and intrinsic phase transition to control the structure of the nanocrystalline material, and obtain a dual-phase bimodal iron-based bulk material The bulk material provides a new preparation idea for a new generation of high-strength and high-plasticity iron-based materials, including the following steps:

[0031] (1) Select element Ni (5-25 at.%) to reduce the phase transition point of the system α→γ phase transition, and select Zr element (0.5-3 at.%) to improve the thermal stability of the iron-based nanocrystalline system;

[0032] (2) After the alloy composition is selected, the grain size of the alloy powder is refined to 20-50 nanometers, and a single-phase bulk material is prepared by high-pressure sintering at a pressure of 2-6GPa and a temperature of 500-100...

Embodiment 1

[0036] Example 1: Fe 91 Ni 8 Zr 1 Preparation of biphasic bimodal alloys

[0037] Alloy composition (atomic percentage): 8% Ni, 1% Zr, the rest is Fe.

[0038] Preparation process: (1) Fe powder, Ni powder and Zr powder are selected, and ferrite single-phase nanocrystalline powder is prepared by high-energy ball milling (process parameters: the rotating speed is 250 rpm, the ball milling time is 50 hours, and the ball-to-material ratio is 10:1, the process control agent is n-hexane); (2) Use six-sided top equipment for ultra-high pressure sintering to prepare ferrite single-phase nanocrystalline bulk materials (process parameters: pressurize to 5.5GPa within 15 minutes, and use 200 The rate of Celsius per minute is heated to 600 degrees Celsius for 10-30 minutes and then cooled, and the pressure is released); (3) the selected ferrite (bcc) average grain size is 50 nanometers, the volume fraction is 65%, and the austenite (fcc) The average grain size is 150 nanometers, the ...

Embodiment 2

[0041] Example 2: Fe 90 Ni 8 Zr 2 Preparation of biphasic bimodal alloys

[0042] Alloy composition (atomic percentage): 8% Ni, 2% Zr, and the rest is Fe.

[0043] Preparation process: (1) Fe powder, Ni powder and Zr powder are selected, and ferrite single-phase nanocrystalline powder is prepared by high-energy ball milling (process parameters: the rotating speed is 250 rpm, the ball milling time is 50 hours, and the ball-to-material ratio is 10:1, the process control agent is n-hexane); (2) Use six-sided top equipment for ultra-high pressure sintering to prepare ferrite single-phase nanocrystalline bulk materials (process parameters: pressurize to 5.5GPa within 15 minutes, and use 200 The rate of Celsius per minute is heated to 600 degrees Celsius for 10-30 minutes and then cooled, and the pressure is released); (3) the selected ferrite (bcc) average grain size is 40 nanometers, the volume fraction is 50%, and the austenite (fcc) The average grain size is 120nm, the volum...

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Abstract

The invention relates to a nanocrystalline / ultra-fine grain dual-phase and dual-peak block material and a preparing method. When a material is subjected to phase change through selection of alloying elements, a system is still in a nano scale; after the elements are selected, nanocrystalline powder is prepared through a high-energy ball milling method, and a single-phase nanocrystalline material is prepared through high-pressure sintering; according to the selected two-phase fraction and grain size, the heat treatment technology is determined through calculation according to a phase diagram; according to the obtained heat treatment technology, short-time annealing is conducted on the single-phase nanocrystalline material at the temperature higher than the polymorphism converting temperature and lower than polymorphism converting ending temperature, part of grains are subjected to phase change, the nano scale grain boundary is utilized for restraining phase boundary migration, accordingly, a new phase is in the ultra-fine grain scale and is retained at the room temperature, and accordingly the nanocrystalline / ultra-fine grain dual-phase and dual-peak iron-based block material with the controllable structure is obtained.

Description

technical field [0001] The invention belongs to a nanocrystalline iron-based bulk material and a preparation method thereof, and relates to a nanocrystalline / ultrafine crystal dual-phase bimodal bulk material and a preparation method thereof. Background technique [0002] The strength and plasticity of metal materials are often incompatible: high strength corresponds to low plasticity, and vice versa; this inversion relationship greatly limits the development of metal materials. Metal nanocrystalline materials have several times the strength of traditional metal coarse-grained materials, but the dislocation storage and proliferation capabilities of nanocrystalline grains are poor, resulting in uneven plastic deformation, poor work hardening ability, and greatly reduced plasticity of metal nanocrystalline materials[Meyers , M.A., Mishra, A. & Benson, D.J. Mechanical properties of nanocrystalline materials. Prog. Mater. Sci. 51, 427-556 (2006).]. Therefore, it is of great sci...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C22C38/08C22C38/14B22F3/16C21D6/00
CPCB22F3/16C21D6/001C21D2211/001C21D2211/005C22C38/08C22C38/14
Inventor 刘峰林为彤黄林科
Owner NORTHWESTERN POLYTECHNICAL UNIV