鋁基復合材料時效行為的影響
吳楨干2， 王鴻華2，張 荻2， 吳人潔2
(1.四川大學 金屬材料工程系， 成都 610065；
2.上海交通大學 金屬基復合材料國家重點實驗室， 上海 200030)
摘 要: 采用擠壓鑄造方法制備mullite/Al-4.0Cu-1.85Mg鋁基復合材料，用硬度測試(HB)、差示掃描量熱儀(DSC)和分析透射電鏡(ATEM)等手段，研究了復合材料及其基體合金的時效硬化特性、時效相的析出序列、析出相和位錯的微觀形貌特征以及界面結構。結果表明： mullite纖維的引入抑制了GPB區(qū)的形成，提高了基體合金的時效硬度，但纖維加速復合材料時效硬化的作用不明顯。這是由于Mg元素在纖維/基體界面處發(fā)生了界面反應，生成鎂鋁尖晶石(MgAl2O4)，使復合材料中非纖維區(qū)內實際Mg含量降低所致。
關鍵字: mullite纖維； Al-Cu-Mg合金；時效； 位錯； 界面反應
on ageing behaviour of short mullite fibre
reinforced Al-4.0Cu-1.85Mg composite
WU Zhen-gan2, WANG Hong-hua2, ZHANG Di2, WU
（1. Department of Metallic Materials Engineering,
Sichuan University, Chengdu 610065,P.R.China;
2. State Key Lab of MMCs, Shanghai Jiaotong University,
Shanghai 200030, P.R.China）
Abstract: Short mullite fibre reinforced Al-4.0Cu-1.85Mg composite and unreinforced monolithic alloy were fabricated through squeeze casting route. The age-hardening behaviour, precipitation procedure, microstructure of dislocation and precipitates and the interfacial structure have been studied by means of hardness measurement(HB), differential scanning calorimetry (DSC) and analytical transmission electron microscope(ATEM), respectively. It is found that short mullite fibre in the composite induces high dislocation density in the near vicinity of the interface after solutionized and ice-water quenched, suppresses or delays the formation of GPB zones. The aged hardness of the composite is always higher than that of the monolithic alloy,but there appears little difference between the times needed in the composite and in the monolith to reach the peak hardness, which means that the acceleration effect of mullite fibre on the precipitation of Al-Cu-Mg alloy is not great enough. It is also found that Mg reacts with Al and SiO2, resulting in the formation of spinel(MgAl2O4)， hence depleting Mgin the matrix and finally hindering the ageing acceleration in the testing composite.
Key words: mullite fibre; Al-Cu-Mg alloy; ageing; dislocation; interfacial reaction
