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Preparation of crystal grain size controllable bimodal distribution block superfine/nanocrystalline alloy

A nanocrystalline alloy, bimodal distribution technology, applied in the field of metal materials, can solve the problems of difficult control of process parameters, poor reproducibility, complex process, etc., and achieve the effect of easy realization, simple realization and high strength index.

Inactive Publication Date: 2009-01-21
NANJING UNIV OF SCI & TECH
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  • Description
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  • Application Information

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Problems solved by technology

However, the process parameters of the partial recrystallization method of Y.M.Wang et al. are difficult to control and the reproducibility is not good; the powder metallurgy method adopted by B.Q.Han et al. has complicated process and high cost

Method used

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  • Preparation of crystal grain size controllable bimodal distribution block superfine/nanocrystalline alloy
  • Preparation of crystal grain size controllable bimodal distribution block superfine/nanocrystalline alloy
  • Preparation of crystal grain size controllable bimodal distribution block superfine/nanocrystalline alloy

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preparation example Construction

[0021] to combine figure 2 , the preparation method of the bulk ultrafine / nanocrystalline alloy with controllable bimodal distribution of grain size in the present invention utilizes the control and improvement effects of alloying, solid-state phase transformation treatment and plastic deformation on the structure, and obtains a bimodal alloy with grain size Bulk nanocrystalline materials with peak distribution characteristics provide a new way to solve the high-strength and low-plasticity defects of bulk nanocrystalline materials, including the following steps:

[0022] (1) Select a two-phase eutectoid or eutectic system, by figure 1 The phase diagram shown is calculated in combination with the lever law, and in the hypoeutectoid / hypoeutectic composition range (according to the characteristics of the proeutectoid / proutectic phase, the alloy composition can also be selected in the hypereutectoid / hypereutectic region) through a reasonable Select the alloy composition and quan...

Embodiment 1

[0027] Example 1: Preparation of Cu-10.8%Al hypo-eutectoid alloy.

[0028] Alloy composition (percentage by weight): 10.8% Al, impurity elements less than 0.02%, and the rest being Cu. The pro-eutectoid phase proportion of the hypo-eutectoid alloy calculated by the lever law is 40%.

[0029] The specific steps of the preparation process of copper-aluminum alloy with bimodal distribution structure of controllable grain size are as follows: (1) After determining and selecting the above-mentioned components, a melting method is used to obtain an alloy ingot with uniform composition and structure. (2) Perform phase change treatment: place the sample in a heating furnace at 850°C for 2 hours to make the alloy uniformly solid solution, then cool (cooling rate V 1 =2~3°C / min) to eutectoid reaction temperature 565°C, water quenching immediately (process route such as image 3shown by the solid line). To change the distribution of the proeutectoid phase, you can pass (eg image 3 d...

Embodiment 2

[0031] Example 2: Preparation of Zn-41%Al hypoeutectoid alloy.

[0032] Alloy composition (percentage by weight): 41% Al, impurity elements less than 0.01%, and the rest being Zn. The pro-eutectoid phase proportion of the hypo-eutectoid alloy calculated by the lever law is 40%.

[0033] The specific steps of the preparation process of zinc-aluminum alloy with bimodal distribution structure of controllable grain size are as follows: (1) After determining and selecting the above-mentioned components, adopt a melting method to obtain an alloy ingot with uniform composition and structure. (2) Perform phase change treatment: place the sample in a heating furnace at 360°C for 24 hours to make the alloy uniformly solid solution, and then cool (the cooling rate is respectively selected V 1 =2~3℃ / min, V 2 =20~30°C / min) to the eutectoid reaction temperature of 275°C, immediately water quenched. (3) After the eutectoid phase transformation treatment, the grains of the sample were refi...

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Abstract

The invention discloses a method for preparing a block superfine / nanocrystal alloy with controllable grain size and bimodal distribution. The method comprises the following steps: firstly, a biphase eutectoid or eutectic is selected and calculated according to a phase diagram combined with a lever rule, and the proportion of a primary eutectoid phase or a primary eutectic phase is quantitively controlled through reasonable selection of alloy compositions; secondly, after the alloy compositions are selected, alloy compositions undergo solution heat treatment and then are cooled, and the size of the primary eutectoid phase or the primary eutectic phase is controlled; thirdly, the alloy structure is thinned through violent plastic deformation or general plastic deformation, and then complete superfine crystal or nanocrystal alloy is obtained; and fourthly, the alloy obtained undergoes short-time annealing under the condition that the temperature is higher than the recrystallization temperature of the primary eutectoid phase or the primary eutectic phase, and then the block superfine / nanocrystal alloy with the controllable grain size and the bimodal distribution structure is obtained. The method realizes controllable grain size and bimodal distribution in the eutectoid or eutectic alloy, quantitively and precisely controls the proportion and the distribution of microcrystals, adopts the technological combinations of design of the alloy compositions, solid phase-transition treatment, plastic deformation and annealing for the first time, and is simple and easy to realize.

Description

a technical field [0001] The invention belongs to the field of metal materials applicable to eutectoid and eutectic system alloys, in particular to a method for realizing the control of grain size bimodal distribution tissue parameters to improve the mechanical properties of bulk ultrafine crystal / nano crystal materials. Two background technology [0002] According to the well-known Hall-Page relationship formula, the strength increases with the decrease of grain size. When the grain size is reduced to submicron or even nanoscale, its strength is much higher than that of ordinary polycrystalline materials. Although the bulk nano-metal materials obtained so far have high strength, their plasticity at room temperature is very low. In fully nanocrystalline materials with a grain size of less than 30 nanometers, they often exhibit extremely low room temperature tensile plasticity, usually less than 5% elongation at break, and exhibit brittle behavior [C.C.Koch, Microsample tens...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C1/00C22F1/00
Inventor 王经涛夏少华
Owner NANJING UNIV OF SCI & TECH
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