元素混合烧结制备Cu-Ni-Si合金及其薄板快速成形工艺
发布时间：2019-07-09 21:18
【摘要】：由于具有高强度、高导电性和无磁致热效应等优点,Cu-Ni-Si合金被认为是最有希望取代Cu-Be合金、成为新型引线框架的主要候选材料。然而,传统熔铸法制备Cu-Ni-Si合金时极易在铜晶界上形成网状不导电金属间化合物相,从而影响合金的强度和导电性,且从铸锭到薄板的加工工艺繁琐,生产成本高、效率低。本文以Cu、Ni和Si单质粉末为原料,结合热压烧结制备Cu-Ni-Si合金块体,通过对烧结体的密度、硬度、导电率和晶粒尺度等进行测量,探索了烧结温度和烧结时间对混合粉末压坯致密化行为的影响,确定了最佳的烧结工艺并对烧结体的显微结构进行了表征。随后,通过实验研究确定了 Ni/Si质量比对Cu-Ni-Si合金强度和导电率的影响规律,考察了固溶和时效处理对烧结态Cu-Ni-Si合金的强度和导电率的影响。最后,积极探索了一种Cu-Ni-Si合金薄板的快速成形工艺,即利用直接粉末轧制技术通过对Cu、Ni和Si单质混合粉末体系进行轧制成形和气氛烧结,制备出了厚度在0.3mm左右的Cu-Ni-Si合金薄板,并对其强度和导电性进行了测试分析。本文得到主要结论如下:1.烧结态Cu-Ni-Si合金组织主要为:基体相α-Cu(Ni, Si)、晶界相Ni31Si12及晶内相δ-Ni2Si组成,其中Ni31Si12相为直径3-5μm的颗粒,主要分布于Cu基体粉末的边界处,δ-Ni2Si相的直径小于1μm,弥散分布于铜基体晶粒内部。与普通熔铸态Cu-Ni-Si合金相比发现,粉末烧结法制备确能抑制晶界上网状Ni31 Si12结构的出现。2.随着烧结温度的升高或烧结时间的延长,烧结体的密度从8.13g/cm~3上升到8.71g/cm~3,烧结体的硬度从99.1HV增大到134.7HV,烧结体的导电率从23.67%IACS提高到28.78%IACS;铜粉末基体的晶粒尺寸逐渐变大,进而致使合金导电率略微下降。因此,确定了最佳的Cu-Ni-Si合金块体的烧结工艺参数为:烧结温度为900℃、烧结时间1h;当Cu含量为90wt.%、Ni、Si质量比为5.4:1时,烧结态Cu-Ni-Si合金的导电率和硬度均达到较高的数值,即29.8%IACS和134HV。3.经固溶和时效处理后,Ni、Si固溶原子从Cu基体中析出形成弥散分布的δ-Ni2Si析出相,由于δ-Ni2Si相对合金导电率影响较小,而且对Cu-Ni-Si合金还存在时效强化的作用,其导电率和硬度较烧结态分别提高了 18.72%和73.13%。4.相比气雾化Cu单质粉末,电解Cu单质粉末更易于轧制成形。一道次轧制后Cu-Ni-Si生坯板材韧性好且不易断裂,其长度可达到170mm; Cu-Ni-Si生坯板材经二道次轧制后其致密度和厚度分别可达到81%和0.38mm;而经三道次轧制后, Cu-Ni-Si生坯板材边缘出现卷曲和开裂现象,且表面发黑,严重影响到Cu-Ni-Si合金薄板的抗拉强度和美观程度。5.初次烧结(烧结温度900℃、烧结时间1h)后Cu-Ni-Si合金板材的致密度从73%逐渐增大至92%,但Cu基体表面存在较多空洞或缺陷,合金板材并未实现完全烧结,因此对Cu-Ni-Si板材进行二次烧结(烧结温度950℃、烧结时间1h),获得的板材组织中颗粒间结合紧密,同时Cu-Ni-Si合金板材的导电率、致密度、抗拉强度和延伸率分别为31%IACS、93%、609.74MPa 和 6.04%。
文内图片：
图片说明：粉末轧机及纯Cu粉末轧制示意图
[Abstract]:The Cu-Ni-Si alloy is considered to be the most promising candidate for the lead frame due to the advantages of high strength, high electrical conductivity and no magneto-caloric effect. However, when a Cu-Ni-Si alloy is prepared by a conventional fusion casting method, a mesh-like non-conductive intermetallic compound phase is easily formed on the copper grain boundary, so that the strength and the conductivity of the alloy are influenced, and the processing technique from the ingot to the thin plate is complex, the production cost is high, and the efficiency is low. In this paper, Cu, Ni and Si elementary powder are used as raw materials, and the Cu-Ni-Si alloy block is prepared by hot-pressing and sintering, and the influence of the sintering temperature and the sintering time on the densification behavior of the mixed powder compact is investigated by measuring the density, the hardness, the conductivity and the grain size of the sintered body. The optimum sintering process was determined and the microstructure of the sintered body was characterized. The influence of the Ni/ Si mass ratio on the strength and the conductivity of the Cu-Ni-Si alloy was determined by the experimental study, and the effect of the solution and aging treatment on the strength and the conductivity of the sintered Cu-Ni-Si alloy was investigated. In the end, a rapid prototyping process of a Cu-Ni-Si alloy sheet is actively explored, that is, a Cu-Ni-Si alloy sheet having a thickness of about 0.3 mm is prepared by rolling and forming a mixed powder system of Cu, Ni and Si by direct powder rolling technology. And the strength and the electrical conductivity are tested and analyzed. The main conclusions are as follows:1. The sintered Cu-Ni-Si alloy is mainly composed of a matrix phase Ni-Cu (Ni, Si), a grain boundary phase Ni31Si12 and a crystal inner phase Ni-Ni2Si, wherein the Ni31Si12 phase is a particle with a diameter of 3-5 & mu; m, and is mainly distributed at the boundary of the Cu matrix powder; and the diameter of the Ni-Ni2Si phase is less than 1. m And the dispersion is distributed inside the crystal grains of the copper matrix. Compared with the common cast-in-state Cu-Ni-Si alloy, it is found that the preparation of the powder sintering method can restrain the appearance of the net-like Ni31 Si12 structure on the grain boundary. As the sintering temperature is raised or the sintering time is prolonged, the density of the sintered body is increased from 8.13 g/ cm to 3, the hardness of the sintered body is increased from 99.1 HV to 134.7 HV, and the conductive rate of the sintered body is increased from 23.67% IACS to 28.78% IACS, and the grain size of the copper powder matrix is gradually increased, which in turn causes a slight decrease in the conductivity of the alloy. Therefore, the optimum sintering process parameters of the Cu-Ni-Si alloy block are determined as follows: the sintering temperature is 900 DEG C, the sintering time is 1 h, and when the Cu content is 90 wt. When the mass ratio of Ni and Si was 5.4:1, the conductivity and hardness of the sintered Cu-Ni-Si alloy reached a higher value, that is, 29.8% IACS and 134HV.3. After the solid solution and the aging treatment, the solution atoms of Ni and Si are separated out from the Cu matrix to form a dispersion-distributed Ni-Ni2Si precipitation phase, and the effect of aging strengthening is also existed for the Cu-Ni-Si alloy due to the small influence on the conductivity of the Ni-Ni2Si relative to the alloy, Its conductivity and hardness were increased by 18.72% and 73.13%, respectively. Compared with the gas-atomized Cu elementary powder, the elemental powder of the electrolytic Cu is easier to roll and form. the toughness of the Cu-Ni-Si green plate after a secondary rolling is good, the toughness is not easy to break, the length of the Cu-Ni-Si green sheet material can reach 170 mm, and the density and the thickness of the Cu-Ni-Si green sheet material can reach 81 percent and 0.38 mm respectively after the two pass rolling, and after three times of rolling, the edge of the Cu-Ni-Si green sheet material is curled and cracked, and the surface is blackened, The tensile strength and the aesthetic degree of the Cu-Ni-Si alloy sheet are seriously affected. The density of Cu-Ni-Si alloy sheet was gradually increased from 73% to 92% after primary sintering (sintering temperature 900 鈩，
本文编号：2512458
文内图片：
图片说明：粉末轧机及纯Cu粉末轧制示意图
[Abstract]:The Cu-Ni-Si alloy is considered to be the most promising candidate for the lead frame due to the advantages of high strength, high electrical conductivity and no magneto-caloric effect. However, when a Cu-Ni-Si alloy is prepared by a conventional fusion casting method, a mesh-like non-conductive intermetallic compound phase is easily formed on the copper grain boundary, so that the strength and the conductivity of the alloy are influenced, and the processing technique from the ingot to the thin plate is complex, the production cost is high, and the efficiency is low. In this paper, Cu, Ni and Si elementary powder are used as raw materials, and the Cu-Ni-Si alloy block is prepared by hot-pressing and sintering, and the influence of the sintering temperature and the sintering time on the densification behavior of the mixed powder compact is investigated by measuring the density, the hardness, the conductivity and the grain size of the sintered body. The optimum sintering process was determined and the microstructure of the sintered body was characterized. The influence of the Ni/ Si mass ratio on the strength and the conductivity of the Cu-Ni-Si alloy was determined by the experimental study, and the effect of the solution and aging treatment on the strength and the conductivity of the sintered Cu-Ni-Si alloy was investigated. In the end, a rapid prototyping process of a Cu-Ni-Si alloy sheet is actively explored, that is, a Cu-Ni-Si alloy sheet having a thickness of about 0.3 mm is prepared by rolling and forming a mixed powder system of Cu, Ni and Si by direct powder rolling technology. And the strength and the electrical conductivity are tested and analyzed. The main conclusions are as follows:1. The sintered Cu-Ni-Si alloy is mainly composed of a matrix phase Ni-Cu (Ni, Si), a grain boundary phase Ni31Si12 and a crystal inner phase Ni-Ni2Si, wherein the Ni31Si12 phase is a particle with a diameter of 3-5 & mu; m, and is mainly distributed at the boundary of the Cu matrix powder; and the diameter of the Ni-Ni2Si phase is less than 1. m And the dispersion is distributed inside the crystal grains of the copper matrix. Compared with the common cast-in-state Cu-Ni-Si alloy, it is found that the preparation of the powder sintering method can restrain the appearance of the net-like Ni31 Si12 structure on the grain boundary. As the sintering temperature is raised or the sintering time is prolonged, the density of the sintered body is increased from 8.13 g/ cm to 3, the hardness of the sintered body is increased from 99.1 HV to 134.7 HV, and the conductive rate of the sintered body is increased from 23.67% IACS to 28.78% IACS, and the grain size of the copper powder matrix is gradually increased, which in turn causes a slight decrease in the conductivity of the alloy. Therefore, the optimum sintering process parameters of the Cu-Ni-Si alloy block are determined as follows: the sintering temperature is 900 DEG C, the sintering time is 1 h, and when the Cu content is 90 wt. When the mass ratio of Ni and Si was 5.4:1, the conductivity and hardness of the sintered Cu-Ni-Si alloy reached a higher value, that is, 29.8% IACS and 134HV.3. After the solid solution and the aging treatment, the solution atoms of Ni and Si are separated out from the Cu matrix to form a dispersion-distributed Ni-Ni2Si precipitation phase, and the effect of aging strengthening is also existed for the Cu-Ni-Si alloy due to the small influence on the conductivity of the Ni-Ni2Si relative to the alloy, Its conductivity and hardness were increased by 18.72% and 73.13%, respectively. Compared with the gas-atomized Cu elementary powder, the elemental powder of the electrolytic Cu is easier to roll and form. the toughness of the Cu-Ni-Si green plate after a secondary rolling is good, the toughness is not easy to break, the length of the Cu-Ni-Si green sheet material can reach 170 mm, and the density and the thickness of the Cu-Ni-Si green sheet material can reach 81 percent and 0.38 mm respectively after the two pass rolling, and after three times of rolling, the edge of the Cu-Ni-Si green sheet material is curled and cracked, and the surface is blackened, The tensile strength and the aesthetic degree of the Cu-Ni-Si alloy sheet are seriously affected. The density of Cu-Ni-Si alloy sheet was gradually increased from 73% to 92% after primary sintering (sintering temperature 900 鈩，
本文编号：2512458
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