【摘要】：鎢銅合金板材既有較高的強(qiáng)度、硬度和較低的熱膨脹系數(shù)還有良好的導(dǎo)電導(dǎo)熱性,在電觸頭,電子封裝材料和熱沉材料等方面應(yīng)用較為廣泛。鎢和銅熔點(diǎn)差大并且互不固溶,使得傳統(tǒng)的鑄錠軋制方法無法制備鎢銅合金板材。利用粉末軋制工藝結(jié)合后續(xù)燒結(jié)工序,是制備鎢銅粉末合金的一條極佳途徑。并且粉末軋制具有很多優(yōu)點(diǎn),如生產(chǎn)的板材成分和組織均勻,工藝簡單,生產(chǎn)成本低等。本文采用有限元數(shù)值模擬和實(shí)際試驗(yàn)相結(jié)合的方法,研究W-Cu20粉末軋制規(guī)律。以鎢粉和銅粉為原料,構(gòu)建W-Cu20粉末的Drucker-Prager/Cap模型,建立W-Cu20粉末軋制有限元模擬模型。將模擬值和實(shí)際試驗(yàn)做對比驗(yàn)證,認(rèn)為本文中的W-Cu20粉末軋制數(shù)值模擬是可信的。根據(jù)模擬結(jié)果分析軋制過程中工藝參數(shù)對模擬結(jié)果的影響規(guī)律。對粉末軋制制備出的W-Cu20生板進(jìn)行燒結(jié),并對燒結(jié)板材的相對密度,顯微組織和力學(xué)性能進(jìn)行了研究。構(gòu)建W-Cu20粉末的Drucker-Prager/Cap模型。首先對金屬鎢粉和銅粉的相貌和粒度進(jìn)行了分析,然后按質(zhì)量比例4:1混合制備出W-Cu20粉末。利用巴西圓盤試驗(yàn)、單軸壓縮試驗(yàn)計(jì)算得到了參數(shù)d和β隨相對密度變化關(guān)系。又設(shè)計(jì)壓縮模具,測量粉末壓縮過程中受到的軸向力和徑向力隨壓縮應(yīng)變的關(guān)系,根據(jù)相關(guān)公式計(jì)算得到了模型參數(shù)R、pa和pb隨相對密度變化的關(guān)系。最后給出了Drucker-Prager/Cap關(guān)于相對密度的空間構(gòu)形。利用有限元軟件Abaqus建立了W-Cu20粉末軋制數(shù)值模擬模型。首先利用Abaqus自帶的幾何造型功能進(jìn)行幾何建模并合理劃分網(wǎng)格。賦予粉末材料Drucker-Prager/Cap模型參數(shù),建立溫度-位移耦合分析步,利用FORTRAN語言編寫的子程序VUSDFLD更新W-Cu20粉末軋制過程中因粉末體變形改變相對密度引起的材料屬性參數(shù)的變化。有限元模擬結(jié)果發(fā)現(xiàn),W-Cu20粉末軋制過程模擬值和實(shí)際值基本吻合,最大誤差為4.73%,認(rèn)為有限元模型的建立有效和可信。工藝參數(shù)對模擬結(jié)果影響比重依次為:軋輥縫隙、軋制速度和軋制溫度。W-Cu20粉末軋制時(shí),軋輥縫隙越大,軋制所得板材相對密度越大,粉末橫向流動(dòng)位移越小;軋制速度越快,所得板材相對密度越小,粉末橫向位移也就越小,溫度場分布越均勻;軋制溫度越高,板材相對密度越大,粉末流動(dòng)性越好。對粉末軋制制備的W-Cu20生坯進(jìn)行液相燒結(jié)。相同軋制溫度制備的生坯,燒結(jié)溫度從1250℃提高到1450℃,試樣的相對密度最大增幅從4.63%升高到11.87%,而制備W-Cu20合金生坯的軋制溫度從80℃升高到150℃,1450℃的燒結(jié)溫度對試樣致密度的提高由11.87%下降到1450℃下的5.3%。1350℃下制備的板材斷裂強(qiáng)度324MPa,硬度平均為224HV,顯微組織觀察表明,鎢相作為基體,銅相填充在鎢相孔隙中。
[Abstract]:Tungsten-copper alloy sheet has high strength, hardness and low coefficient of thermal expansion, and good conductivity and thermal conductivity. It is widely used in electric contact, electronic packaging material and heat sink material. The difference of melting point between tungsten and copper makes it impossible for traditional ingot rolling method to prepare tungsten-copper alloy sheet. It is an excellent way to prepare tungsten-copper powder alloy by powder rolling combined with subsequent sintering process. Powder rolling has many advantages, such as uniform composition and structure, simple process, low production cost and so on. In this paper, the law of W-Cu20 powder rolling is studied by means of finite element numerical simulation and practical test. Using tungsten and copper powder as raw materials, the Drucker-Prager/Cap model of W-Cu20 powder was constructed, and the finite element simulation model of W-Cu20 powder rolling was established. The numerical simulation of W-Cu20 powder rolling in this paper is proved to be credible. According to the simulation results, the influence of process parameters on the simulation results is analyzed. The W-Cu20 raw plate prepared by powder rolling was sintered, and the relative density, microstructure and mechanical properties of the sintered plate were studied. The Drucker-Prager/Cap model of W-Cu20 powder was constructed. The appearance and particle size of tungsten powder and copper powder were analyzed, and then W-Cu20 powder was prepared by mixing at 4:1. The variation of parameters d and 尾 with relative density was calculated by using Brazilian disk test and uniaxial compression test. A compression die was designed to measure the relationship between the axial and radial forces in the process of powder compression and the compressive strain. The relationship between the model parameters RPA and pb with the relative density was calculated according to the relevant formulas. Finally, the spatial configuration of the relative density of Drucker-Prager/Cap is given. The numerical simulation model of W-Cu20 powder rolling was established by using finite element software Abaqus. Firstly, the geometric modeling function of Abaqus is used to model the geometry and the mesh is divided reasonably. The parameters of Drucker-Prager/Cap model are given to the powder material, and the temperature displacement coupling analysis step is established. The change of the material property parameters caused by the change of the relative density of the powder body deformation during the rolling process of W-Cu20 powder is updated by the subprogram VUSDFLD compiled by FORTRAN language. The results of finite element simulation show that the simulated value of W-Cu20 powder rolling process is basically consistent with the actual value, and the maximum error is 4.73. It is considered that the establishment of finite element model is effective and reliable. The influence of process parameters on the simulation results is as follows: roll gap, rolling speed and rolling temperature. When W-Cu20 powder rolling, the bigger the roll gap, the greater the relative density of rolled plate, the smaller the transverse displacement of powder, the faster the rolling speed, the faster the rolling speed. The smaller the relative density of the plate, the smaller the transverse displacement of the powder and the more uniform the temperature field distribution; the higher the rolling temperature, the greater the relative density of the plate, the better the powder fluidity. The W-Cu20 billet prepared by powder rolling was sintered in liquid phase. The sintering temperature of the billet prepared at the same rolling temperature was raised from 1250 鈩，

本文編號：2286443