碳纳米管增强锌基复合材料的制备及其热变形行为研究
发布时间：2018-08-21 12:42
【摘要】：本文采用高能球磨(HEM)+真空烧结(P/M)法制备具有核壳结构特征的(CNTs Al)/ZA27复合材料。首先采用球磨混粉法将CNTs包覆在Al粉内,形成(CNTs Al)混合增强体,然后采用HEM P/M法制备(CNTs Al)/ZA27复合材料。通过对复合材料进行显微组织观察、力学性能检测以及热模拟试验,系统研究了制备工艺参数、CNTs含量、热变形工艺参数等对复合材料微观组织和力学性能的影响规律。通过球磨混粉(200 rpm/1 h)+高能球磨(400 rpm/8 h),成功制备出具有核壳结构特征的(CNTs Al)/ZA27复合粉末,有效的实现了CNTs在基体粉末中的均匀分散;在压制压力为300 MPa时,压坯密度和烧结密度最大;采用真空烧结方法制备(CNTs Al)/ZA27复合材料,通过微观组织分析表明,复合材料主要存在α-Al相、η-Zn相以及β-ZnAl相,未发现明显的Al4C3等碳化合物,表明CNTs与基体没有发生剧烈反应,保证了增强体与基体良好的结合性。同时,研究烧结工艺和CNTs含量对复合材料微观组织和力学性能的影响,当复合材料在480℃烧结温并保温时间2h时,(CNTs Al)/ZA27复合材料的致密度最大,抗拉性能最优。当CNTs含量为0.4 wt.%时,晶粒明显细化,抗拉强度及伸长率得到显著提升,复合材料的强化主要来自细晶强化,载荷传递强化,热失配引起的几何位错强化,以及CNTs阻碍位错运动产生的位错强化等。在变形温度473 623 K和应变速率0.01 10 s-1内,对(CNTs Al)/ZA27复合材料进行了热压缩模拟试验,研究了不同变形温度和应变速率对复合材料流变应力的影响规律。基于试验结果,建立了两种流变应力预测模型,即改进的Arrhenius本构模型和人工神经网络(ANN)模型,并对两种流变应力预测模型的预测精度进行了计算,其中改进的Arrhenius方程模型的相关误差范围和均方根误差分别为-15.93 17.29%和6.81 MPa,ANN模型的相关误差范围和均方根误差分别为-4.14 6.75%和1.57 MPa。相比于改进的Arrhenius模型,ANN模型的流变应力预测值与实验值的各项误差均较低,预测结果与试验数据吻合较好,表明利用ANN建立的流变应力模型,可较好地反映复合材料的热变形行为。基于动态材料模型,建立了(CNTs Al)/ZA27复合材料的3D加工图,并结合显微组织观察,确定了(CNTs Al)/ZA27复合材料的最佳热加工参数区为变形温度550 590 K,应变速率0.01 0.35 s-1,在此变形参数区,材料的软化机制主要为动态再结晶。
[Abstract]:In this paper (CNTs / Al) / ZA27 composites with core-shell structure were prepared by high energy ball milling (HEM) vacuum sintering (P / M) method. Firstly, CNTs was coated in Al powder by ball milling method to form (CNTs / Al) mixed reinforcements. Then (CNTs / Al) / ZA27 composites were prepared by HEM / P / M method. By observing the microstructure of the composites, testing the mechanical properties and thermal simulation tests, the effects of the preparation process parameters such as the content of CNTs and the thermal deformation parameters on the microstructure and mechanical properties of the composites were systematically studied. The (CNTs / ZA27) / ZA27 composite powder with core-shell structure was successfully prepared by ball milling (200 rpm/1 h) high energy ball milling (400 rpm/8 h), which effectively realized the uniform dispersion of CNTs in the matrix powder, and when the pressing pressure was 300 MPa, The compaction density and sintering density were the largest, and the microstructure analysis of (CNTs / ZA27) / ZA27 composites prepared by vacuum sintering showed that there were mainly 伪 -Al phase, 畏 -Zn phase and 尾 -ZnAl phase, and no obvious Al4C3 and other carbon compounds were found in the composites. The results show that there is no violent reaction between CNTs and matrix, which ensures the good bonding between the reinforcement and matrix. At the same time, the effects of sintering process and CNTs content on the microstructure and mechanical properties of the composites were studied. When the composites were sintered at 480 鈩，
本文编号：2195771
[Abstract]:In this paper (CNTs / Al) / ZA27 composites with core-shell structure were prepared by high energy ball milling (HEM) vacuum sintering (P / M) method. Firstly, CNTs was coated in Al powder by ball milling method to form (CNTs / Al) mixed reinforcements. Then (CNTs / Al) / ZA27 composites were prepared by HEM / P / M method. By observing the microstructure of the composites, testing the mechanical properties and thermal simulation tests, the effects of the preparation process parameters such as the content of CNTs and the thermal deformation parameters on the microstructure and mechanical properties of the composites were systematically studied. The (CNTs / ZA27) / ZA27 composite powder with core-shell structure was successfully prepared by ball milling (200 rpm/1 h) high energy ball milling (400 rpm/8 h), which effectively realized the uniform dispersion of CNTs in the matrix powder, and when the pressing pressure was 300 MPa, The compaction density and sintering density were the largest, and the microstructure analysis of (CNTs / ZA27) / ZA27 composites prepared by vacuum sintering showed that there were mainly 伪 -Al phase, 畏 -Zn phase and 尾 -ZnAl phase, and no obvious Al4C3 and other carbon compounds were found in the composites. The results show that there is no violent reaction between CNTs and matrix, which ensures the good bonding between the reinforcement and matrix. At the same time, the effects of sintering process and CNTs content on the microstructure and mechanical properties of the composites were studied. When the composites were sintered at 480 鈩，
本文编号：2195771
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