發(fā)布時間：2018-03-17 04:11

  本文選題：納米SiCp　切入點：鋁基復合材料　出處：《哈爾濱工業(yè)大學》2015年碩士論文　論文類型：學位論文

【摘要】：鋁基復合材料具有良好的強度、耐磨性和導熱性能的特點,在航空、航天和民用領域得到了大量的應用。納米顆粒增強鋁基復合材料可以實現復合材料強度、韌性、硬度和耐磨性等性能的結合,具有優(yōu)異的強度和韌性。半固態(tài)觸變成形技術可以有效地避免鑄造過程中的紊流和熱裂。本文結合納米顆粒增強鋁基復合材料的制備方法和鋁合金半固態(tài)成形技術,實現高性能納米增強鋁基復合材料結構件的成形制造,促進半固態(tài)觸變成形技術在納米顆粒增強鋁基復合材料結構件成形方面的應用。采用超聲輔助半固態(tài)機械攪拌方法制備納米Si C顆粒增強7075鋁基復合材料,復合材料的微觀組織具有明顯的球狀晶特征,晶粒平均尺寸為30μm,納米Si C顆粒在晶粒內部均勻分布,在晶界處存在一定的偏聚。鋁基復合材料等溫處理過程中固相晶粒尺寸和圓整度取決于等溫溫度和等溫時間,保溫溫度為590℃和600℃時制備的半固態(tài)坯料具有較小的晶粒尺寸和較好的圓整度,當保溫時間大于20min時,坯料中固相長大顯著,出現了明顯的薔薇組織。利用Deform-2D有限元軟件對納米Si C顆粒增強7075鋁基復合材料觸變成形過程進行了數值模擬分析。模擬結果表明,觸變成形過程中的等效應力隨著坯料溫度的升高逐漸減小,成形件不同位置處的等效應變數值相近,提升模具溫度和凸模速度可以有效地減緩坯料熱量的散失。開展了納米Si C顆粒增強7075鋁基復合材料半固態(tài)觸變成形實驗研究,研究結果表明,觸變變形的復合材料觸變成形筒形件不同位置處的金相存在較大差異,晶粒沿著擠壓方向被嚴重拉長,側壁區(qū)域的晶粒在垂直擠壓方向上變形量相對較小,觸變成形過程中納米Si C顆粒在基體中的分布沒有發(fā)生變化,晶界處Si C顆粒的分布高于晶粒內部的分布。成形件力學性能中屈服強度達到245MPa,比原材料提高了53%,抗拉強度達到313MPa,提高了2.3%,筒形件側壁的抗拉強度高于底部區(qū)域的抗拉強度,側壁區(qū)域的斷裂方式以韌性斷裂為主。經過T6熱處理后,材料中Cu元素的偏聚得到解決,抗拉強度達到552MPa,比原材料提高了12.7%,延伸率達到8%,與原材料7075鋁合金的延伸率相近。在室溫大氣環(huán)境下材料的耐磨性沒有得到明顯的提高,材料的磨損形式主要是磨粒磨損。
[Abstract]:Aluminum matrix composites have been widely used in aeronautical, aerospace and civil fields because of their good strength, wear resistance and thermal conductivity. The combination of hardness and wear resistance, With excellent strength and toughness, semi-solid thixoforming technology can effectively avoid turbulence and hot cracking in casting process. In this paper, the preparation method of nano-particle reinforced aluminum matrix composite and semi-solid forming technology of aluminum alloy are combined. To realize the forming manufacture of high performance nano-reinforced aluminum matrix composite structure, To promote the application of semi-solid thixoforming technology in the forming of nano-particle reinforced aluminum matrix composite structure, the ultrasonic assisted semi-solid mechanical stirring method was used to prepare the nano-Si C particle reinforced 7075 aluminum matrix composite. The microstructures of the composites have obvious spherulite characteristics, the average grain size is 30 渭 m, and the nano sic particles distribute uniformly in the grains. During the isothermal treatment of aluminum matrix composites, the grain size and roundness of solid phase depend on the isothermal temperature and time. The semi-solid billets prepared at the holding temperature of 590 鈩，

本文編號：1623096