【摘要】：本文采用高能球磨(HEM)+真空燒結(jié)(P/M)法制備具有核殼結(jié)構(gòu)特征的(CNTs Al)/ZA27復合材料。首先采用球磨混粉法將CNTs包覆在Al粉內(nèi),形成(CNTs Al)混合增強體,然后采用HEM P/M法制備(CNTs Al)/ZA27復合材料。通過對復合材料進行顯微組織觀察、力學性能檢測以及熱模擬試驗,系統(tǒng)研究了制備工藝參數(shù)、CNTs含量、熱變形工藝參數(shù)等對復合材料微觀組織和力學性能的影響規(guī)律。通過球磨混粉(200 rpm/1 h)+高能球磨(400 rpm/8 h),成功制備出具有核殼結(jié)構(gòu)特征的(CNTs Al)/ZA27復合粉末,有效的實現(xiàn)了CNTs在基體粉末中的均勻分散;在壓制壓力為300 MPa時,壓坯密度和燒結(jié)密度最大;采用真空燒結(jié)方法制備(CNTs Al)/ZA27復合材料,通過微觀組織分析表明,復合材料主要存在α-Al相、η-Zn相以及β-ZnAl相,未發(fā)現(xiàn)明顯的Al4C3等碳化合物,表明CNTs與基體沒有發(fā)生劇烈反應,保證了增強體與基體良好的結(jié)合性。同時,研究燒結(jié)工藝和CNTs含量對復合材料微觀組織和力學性能的影響,當復合材料在480℃燒結(jié)溫并保溫時間2h時,(CNTs Al)/ZA27復合材料的致密度最大,抗拉性能最優(yōu)。當CNTs含量為0.4 wt.%時,晶粒明顯細化,抗拉強度及伸長率得到顯著提升,復合材料的強化主要來自細晶強化,載荷傳遞強化,熱失配引起的幾何位錯強化,以及CNTs阻礙位錯運動產(chǎn)生的位錯強化等。在變形溫度473 623 K和應變速率0.01 10 s-1內(nèi),對(CNTs Al)/ZA27復合材料進行了熱壓縮模擬試驗,研究了不同變形溫度和應變速率對復合材料流變應力的影響規(guī)律。基于試驗結(jié)果,建立了兩種流變應力預測模型,即改進的Arrhenius本構(gòu)模型和人工神經(jīng)網(wǎng)絡(ANN)模型,并對兩種流變應力預測模型的預測精度進行了計算,其中改進的Arrhenius方程模型的相關(guān)誤差范圍和均方根誤差分別為-15.93 17.29%和6.81 MPa,ANN模型的相關(guān)誤差范圍和均方根誤差分別為-4.14 6.75%和1.57 MPa。相比于改進的Arrhenius模型,ANN模型的流變應力預測值與實驗值的各項誤差均較低,預測結(jié)果與試驗數(shù)據(jù)吻合較好,表明利用ANN建立的流變應力模型,可較好地反映復合材料的熱變形行為�；趧討B(tài)材料模型,建立了(CNTs Al)/ZA27復合材料的3D加工圖,并結(jié)合顯微組織觀察,確定了(CNTs Al)/ZA27復合材料的最佳熱加工參數(shù)區(qū)為變形溫度550 590 K,應變速率0.01 0.35 s-1,在此變形參數(shù)區(qū),材料的軟化機制主要為動態(tài)再結(jié)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 偽 -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，

本文編號：2195771