阅读说明：本技术 一种含Nb和Al的钛青铜合金带材及其制备方法 (Nb and Al-containing titanium bronze alloy strip and preparation method thereof ) 是由 唐宁 张镇凯 支月鹏 杨谏 武博 于 2020-06-24 设计创作，主要内容包括：本发明公开了一种含Nb和Al的钛青铜合金带材,其特征在于：该钛青铜合金带材的重量百分比组成包括2.00-4.50wt％的Ti,0.005-0.4wt％的Nb,和0.01-0.5wt％的Al,余量为Cu和不可避免的杂质。优选地,该钛青铜合金带材的微观组织中粒径在50-500nm之间的含Nb和Al的金属间化合物粒子的数量不低于1×10<Sup>5</Sup>个/mm<Sup>2</Sup>,粒径大于1μm的含Nb和Al的金属间化合物粒子的数量不高于1×10<Sup>3</Sup>个/mm<Sup>2</Sup>。在确保优异的折弯性能的情况下,该钛青铜合金带材具有优异的稳定性,尤其是在高温下力学性能的稳定性。本发明还涉及该钛青铜合金带材的制备方法。(The invention discloses a titanium bronze alloy strip containing Nb and Al, which is characterized in that: the titanium bronze alloy strip consists ofComprising 2.00 to 4.50 wt% of Ti, 0.005 to 0.4 wt% of Nb, and 0.01 to 0.5 wt% of Al, the balance being Cu and unavoidable impurities preferably, the number of Nb and Al-containing intermetallic compound particles having a particle diameter of 50 to 500nm in the microstructure of the titanium bronze alloy strip is not less than 1 × 10 5 Per mm 2 The number of Nb and Al-containing intermetallic compound particles having a particle diameter of more than 1 μm is not more than 1 × 10 3 Per mm 2 . The titanium bronze alloy strip has excellent stability, particularly mechanical properties at high temperatures, while ensuring excellent bending properties. The invention also relates to a preparation method of the titanium bronze alloy strip.)

1. A Nb and Al containing titanium bronze alloy strip characterized by: the titanium bronze alloy strip comprises, by weight, 2.0-4.5 wt% of Ti, 0.005-0.40 wt% of Nb, 0.01-0.50 wt% of Al, and the balance of Cu and unavoidable impurities.

2. A Nb-and Al-containing titanium bronze alloy strip according to claim 1, wherein: the titanium bronze alloy strip comprises the following components in percentage by weight: 2.5-4.0 wt% Ti, preferably 2.9-3.5 wt% Ti; and/or 0.01 to 0.3 wt% Nb; and/or 0.05-0.3 wt% Al.

3. A Nb-and Al-containing titanium bronze alloy strip according to claim 1 or 2, wherein: the particle size of the titanium bronze alloy strip is 50-500nmThe number of Nb and Al-containing intermetallic compound particles of (1) or more 1 × 10⁵Per mm²The number of Nb and Al-containing intermetallic compound particles having a particle diameter of more than 1 μm is not more than 1 × 10³Per mm²。

4. A Nb-and Al-containing titanium bronze alloy strip according to claim 1 or 2, wherein: after the titanium bronze alloy strip is subjected to heat preservation for 1H at 500 ℃ in the atmosphere, the hardness attenuation rate H is less than 5%.

5. A Nb-and Al-containing titanium bronze alloy strip according to claim 1 or 2, wherein: (1) the bending radius of the titanium bronze alloy strip parallel to the rolling direction is compared with the thickness ratio R of the strip₁T is less than or equal to 0.5, and the ratio R of the bending radius perpendicular to the rolling direction to the thickness of the strip₂the/T is less than or equal to 1.0; and/or (2) the titanium bronze alloy strip has a yield strength greater than 900MPa and an electrical conductivity of 10-20% IACS.

6. A Nb-and Al-containing titanium bronze alloy strip according to claim 1 or 2, wherein: the titanium bronze alloy strip also comprises 0-0.50 wt% of one or more of Ni, Co, Fe, Sn, Mn, Si, Cr, Mg, B, Zr and Ag.

7. Method for producing a Nb-and Al-containing titanium bronze alloy strip according to any of claims 1 to 6, characterized in that it comprises the following steps:

1) casting: melting the copper alloy raw material at 1200-1400 ℃ by adopting a vacuum or atmosphere protection melting method;

2) hot processing: carrying out hot processing on the ingot at the temperature of 700 plus 980 ℃, and controlling the reduction of the cross section area of the hot processing of the ingot to be not less than 75 percent;

3) milling a surface: milling the surface of the material obtained by hot processing;

4) first cold rolling: controlling the reduction of the cross section area of the material to be not less than 70 percent;

5) solution treatment: heating the cold-rolled material to the temperature of 700-950 ℃ and preserving the heat for 1-100s, and then carrying out water cooling or air cooling treatment, wherein the cooling speed is controlled at 10-250 ℃/s;

6) intermediate cold rolling: controlling the cross section area of the material to be reduced by 5-99%;

7) first time aging: selecting non-active atmosphere for protection, and keeping the temperature within the temperature range of 350-500 ℃ for 0.5-24 h;

8) and (3) final cold rolling: controlling the area of the cross section to be reduced by 5-80%;

9) and (3) secondary aging: selecting non-active atmosphere protection and keeping the temperature for 1min-10h within the temperature range of 200-550 ℃.

8. The method of claim 7, wherein one or more of the following is satisfied:

the casting mode in the step 1) is iron mold casting, horizontal continuous casting or vertical semi-continuous casting;

the hot working in the step 2) is hot forging, hot rolling or the combination of the hot forging and the hot rolling;

milling the upper and lower surfaces of the material by 0.5-2.0mm in the step 3) to remove surface defects;

performing multi-pass cold rolling in the step 6), wherein the single-pass deformation is controlled to be 5-20%;

the solution treatment of the step 5) and the intermediate cold rolling of the step 6) are taken as a step unit, the step unit is repeatedly carried out at least twice, wherein the cross section area of the intermediate cold rolled material between two adjacent solution treatments is reduced by more than or equal to 30 percent; and

the ageing in step 7) and/or step 9) is carried out in an atmosphere comprising hydrogen, nitrogen, argon, or any mixture of these gases.

9. The process defined in claim 7 or claim 8 wherein in step 1) the smelting process is divided into three steps, the first step: adding electrolytic copper and Nb-containing intermediate alloy into a smelting furnace at the same time, and starting smelting; the second step is that: after the electrolytic copper and the Nb-containing intermediate alloy are completely melted, sequentially adding a raw material containing Ti and Al and optionally one or more raw materials containing one or more of Ni, Co, Fe, Sn, Mn, Si, Cr, Mg, B, Zr and Ag; the third step: all the raw materials are melted and refined at 1300 +/-50 ℃ for 30-60min, and then cast into ingots.

10. The method according to claim 9, wherein the Nb-containing master alloy is a Cu-Nb master alloy or a Nb-Ti master alloy, the Ti-containing, Al-containing raw material is pure Ti, pure Al or a Ti and/or Al-containing master alloy, and the one or more raw materials containing one or more of Ni, Co, Fe, Sn, Mn, Si, Cr, Mg, B, Zr and Ag are the elements or master alloys containing these elements.

Technical Field

The invention belongs to the technical field of copper alloy materials, and particularly relates to a titanium bronze alloy strip containing Nb and Al. The titanium bronze alloy strip has excellent stability, especially mechanical properties at high temperatures. The invention also relates to a preparation method of the titanium bronze alloy strip.

Background

With the rapid development of miniaturization and multi-functionalization of products in consumer electronics and other connector related industries, designers need to select copper alloy materials with higher strength and better formability to manufacture the contact element therein, so as to meet the design requirements of lightness, thinness and miniaturization of the terminal products. In the existing copper alloy system, beryllium copper alloy which is a representative of high strength and high conductivity can meet the performance requirements, but the use of the material is limited due to the problems of cost and generation of highly toxic substances in the processing process of beryllium-containing materials. The titanium bronze alloy is a copper alloy with titanium as a main alloy element, has high strength and excellent forming performance, and can be used for replacing beryllium copper alloy in some application occasions.

The titanium bronze is an AM decomposition strengthening and time-effect precipitation strengthening type alloy, and the main strengthening structures are an AM decomposition structure and β' -Cu₄In the early stage of aging treatment, the strengthening mode of the titanium bronze alloy is amplitude modulation decomposition strengthening, Ti atoms dissolved in the copper matrix are diffused to form a periodic Ti atom enrichment region in crystal grains, namely an amplitude modulation decomposition structure, and the amplitude modulation decomposition structure is gradually converted into β' -Cu atoms arranged periodically as the aging process continues₄A Ti phase. However, it is not limited toAm decomposition of tissue with β' -Cu₄The Ti phase has poor stability at high temperature and is easy to evolve, thereby causing adverse effect on the mechanical property of the alloy, and the property deteriorates more rapidly at higher temperature. In the material processing and application process, the stability of the material performance is crucial, and the good stability ensures that the product cannot rapidly lose efficacy when sudden overload and high temperature occur in the processing and application process. The titanium bronze has high strength and excellent elastic property, so that the titanium bronze has wide application prospects in the fields of electric automobiles, 5G communication base stations and the like. Transient or sustained high temperature conditions, which may reach temperatures above 200 ℃, are common in these areas, especially in the area of electric vehicles. If the material is developed, the mechanical property stability of the material at high temperature and the performance change condition of the material after use under the high-temperature working condition are not considered, so that the service life of the component prepared from the material under the high-temperature working condition is uncertain, and the component even has the risk of sudden failure, thereby causing great potential safety hazard. Therefore, when a titanium bronze alloy material system is designed, the requirements of various subsequent processing and application scenes of the material cannot be completely met only by regulating and controlling the conventional strength, conductivity, processing performance and the like. The stability of the performance of the titanium bronze alloy material, particularly the stability of the mechanical performance at high temperature, is considered while considering the conventional performance index.

By the present inventors' search, no research on the mechanical property stability of the titanium bronze alloy strip at high temperature has been found in the prior art.

Disclosure of Invention

According to the invention, a certain amount of Nb and Al are added into titanium bronze at the same time, so that a Cu-Ti-Nb-Al system alloy is designed. Compared with the conventional titanium bronze alloy, the Cu-Ti-Nb-Al system alloy has the advantages that the excellent bending property is ensured, the stability of the mechanical property of the Cu-Ti-Nb-Al system alloy at high temperature is obviously improved, and the strength of the alloy is also improved.

The technical problem to be solved by the invention is as follows: aiming at the defects of the prior art, how to ensure the excellent mechanical property and bending property of the titanium bronze alloy strip and enable the alloy strip to have optimized stability, especially the stability of the mechanical property at high temperature.

The technical scheme adopted by the invention for solving the technical problems is as follows: a Nb and Al containing titanium bronze alloy strip having a composition, in weight percent, comprising: 2.0-4.5 wt% of Ti, 0.005-0.4 wt% of Nb, 0.01-0.5 wt% of Al, and the balance of Cu and inevitable impurities.

The invention adds 2.0-4.5 wt% Ti in the titanium bronze alloy strip. Ti contributes to improving the mechanical properties of the titanium bronze alloy. When the content of Ti added is less than 2.0 wt%, the titanium bronze alloy strip does not obtain ideal mechanical properties although it has high electrical conductivity, and thus is limited in application. When the content of Ti added exceeds 4.5 wt%, too high content of Ti may reduce the electrical conductivity of the alloy strip and significantly deteriorate its workability, especially bending property. Thus, the Ti content of the titanium bronze alloy strip of the present invention is 2.0 to 4.5 wt%. Preferably, the Ti content of the titanium bronze alloy strip is 2.5-4.0 wt%. Further preferably, the Ti content of the titanium bronze alloy strip is 2.9-3.5 wt%.

In the invention, Ti is a main strengthening element, an amplitude-modulated decomposition structure is formed by the diffusion of Ti atoms in a solid solution in the aging process, the strength of the copper alloy is obviously improved, and needle-shaped β' -Cu is gradually precipitated from a matrix along with the increase of the aging time₄Ti phase, in which the ageing strengthening effect gradually reaches the peak, and as the ageing time is further prolonged, β -Cu sheets are separated out on the grain boundary₄Ti phase, the volume fraction of which gradually increases with time and finally replaces β' -Cu₄Ti phase, in which the strengthening effect of the copper alloy gradually decreases, spinodal decomposition into a uniform nanoscale structure, β' -Cu₄The Ti phase is also a nano-scale precipitation phase and is dispersed in the matrix, and the two tissues can block the movement of grain boundaries and dislocation, so that the strength of the copper alloy is improved. By controlling the aging process, different microstructures are formed, and the comprehensive performance of the alloy can be effectively regulated and controlled.

Drawings

FIG. 1 shows the metallographic structure of a Cu-Ti-Nb-Al alloy strip according to the invention.

FIG. 2 shows the metallographic structure of a Cu-Ti alloy strip of the prior art.

FIG. 3 is a metallographic structure of a Cu-Ti-Nb alloy strip of the prior art.

FIG. 4 shows the metallographic structure of a Cu-Ti-Al alloy strip of the prior art.

Fig. 5 is a scanning electron microscope picture of intermetallic compounds containing Nb and Al in Cu-Ti-Nb-Al alloy strip according to the present invention.

Detailed Description

The invention is described in further detail below with reference to the figures and examples.

20 example and 10 comparative example alloys were designed. Each alloy adopts the smelting method of the two-step alloy raw material addition according to the requirement of the addition amount of the alloy raw material (see the following table 1), and the first step is as follows: adding electrolytic copper and Cu-Nb intermediate alloy into a smelting furnace at the same time, and starting smelting; the second step is that: after the electrolytic copper and the Cu-Nb intermediate alloy are completely melted, pure Ti, pure Al and simple substances of optional elements selected from Ni, Co, Fe, Sn, Mn, Si, Cr, Mg, B, Zr and Ag are sequentially added according to the components in the table 1; the third step: all raw materials are melted and refined at 1300 + -50 deg.C for 30-60 min. After smelting, rectangular ingots are cast by a vertical semi-continuous casting method.

And (2) carrying out heat preservation on the ingot at the temperature of 800-950 ℃ for 1-12h, carrying out hot rolling at the hot rolling speed of 50-120m/min, controlling the single-pass processing rate of rolling to be 10-30%, controlling the final rolling temperature to be above 650 ℃, carrying out online water cooling after the hot rolling, and carrying out face milling after the hot rolling.

Then, the first cold rolling is carried out, and the total reduction ratio of the cold rolling is controlled to be more than 80%.

Solid solution is carried out after the first cold rolling, the solid solution temperature is 700-950 ℃, the heat preservation time is 1-100s, and the cooling speed is 10-250 ℃/s.

After solid solution, intermediate cold rolling is carried out, the rolling rate is controlled to be 30-60%, and the single-pass deformation is controlled to be 5-20%.

And carrying out secondary solid solution after intermediate cold rolling, wherein the solid solution temperature is 700-950 ℃, the heat preservation time is 1-100s, and the cooling speed is 10-250 ℃/s.

After the secondary solution treatment, the intermediate cold rolling is carried out again, the rolling rate is controlled to be 10-60%, and the single-pass deformation is controlled to be 5-20%.

It should be noted that: although the above intermediate cold rolling step involves a specific rolling reduction and two solution treatments and two intermediate cold rolling, the rolling reduction may vary in the range of 5 to 99% according to the actual finished product specification requirements, and the number of solution treatments and intermediate cold rolling may be one or more than two.

Followed by a first ageing in an atmosphere comprising hydrogen, nitrogen, argon or any mixture of these gases at 400 c for a holding time of 4 h.

And carrying out final cold rolling after the first time aging, wherein the rolling rate is controlled to be 10-30%. It should be noted that: although specific rolling reduction is involved in the final cold rolling step herein, the rolling reduction may vary in the range of 5-80% depending on the actual finished product specification requirements.

And finally, carrying out secondary aging in an atmosphere containing hydrogen, nitrogen, argon or any mixture of the gases, wherein the aging temperature is 350 ℃, and the holding time is 4 h.

It should be noted that although a specific gas atmosphere is used during the first and second aging, it is understood that other inert gases may be used as the protective atmosphere.

The number of Nb and Al containing intermetallic particles in the alloy with a particle size between 50-500nm and a particle size >1 μm was then measured and the resulting alloy strip was tested for mechanical properties, electrical conductivity, bending properties and mechanical stability at high temperature.

In order to avoid making the description of the present application redundant, detailed process parameters of example 12 are described below as an example. Although the detailed process parameters of other embodiments are not described, it should be understood that the disclosure of the present specification is sufficient to enable one skilled in the art to practice the claimed invention and that such disclosure can fully support the scope of the claims.