(中國航發(fā)北京航空材料研究院 鋼與稀貴金屬研究所，北京100095)
摘 要: 利用透射電子顯微鏡(TEM)觀察和分析了7055-T7751預(yù)拉伸厚板中的一種納米尺度析出相，采用選區(qū)電子衍射(SAED)分析方法以及能譜成分分析方法(EDS)對析出相的結(jié)構(gòu)和成分進(jìn)行了表征，并結(jié)合析出相的明場像和高分辨(HRTEM)像，確定了析出相的種類、形貌和分布特征；通過分析基體α(Al)的五個(gè)低指數(shù)晶帶軸([100]、[110]、[111]、[112]和[013])的SAED圖特征，確定了納米析出相與基體之間的取向關(guān)系；采用會(huì)聚束電子衍射(CBED)分析方法測定了入射電子束方向鋁合金試樣的局部厚度，分析了這種析出相的數(shù)密度。結(jié)果表明：7055-T7751預(yù)拉伸厚板中存在納米尺度析出相Al2ZnZr，呈球形或圓片狀，尺寸大多在20 nm左右；Al2ZnZr為簡單立方(SC)結(jié)構(gòu)，點(diǎn)陣參數(shù)為a=0.403 nm；7055-T7751預(yù)拉伸厚板中析出相Al2ZnZr的數(shù)密度約為3.44×1011 mm-3；簡單立方(SC)結(jié)構(gòu)的析出相Al2ZnZr與面心立方(FCC)結(jié)構(gòu)的基體α(Al)之間存在共格關(guān)系，二者之間的取向關(guān)系為 、〈001〉Al//〈001〉 。
關(guān)鍵字: 7055鋁合金；Al2ZnZr；析出相；取向關(guān)系；會(huì)聚束電子衍射；薄晶體厚度；數(shù)密度
（Department of Steel and Rare-Noble Metals, AECC Beijing Institute of Aeronautical Materials, Beijing 100095, China）
Abstract:In this paper, a kind of nano-scale precipitate in 7055-T7751 aluminum alloy was studied by TEM. Bright field images and HRTEM images were observed in order to determine the morphology and distribution characteristics. SAED and EDS analysis were performed to characterize the composition and structure. In addition, by analyzing the SAED patterns of five low-index zone axes of α(Al) (including [100], [110], [111], [112] and [013]), the orientation relationship between the precipitates and the matrix was determined. Finally, the local thickness of the aluminum alloy specimen was measured by CBED, and the number density of this precipitate was further determined. The results show that there are nano-scale Al2ZnZr precipitates in 7055-T7751 pre-stretched thick plate. The precipitates are spherical or dics-shaped, and most of them are about 20 nm in size. The structure of Al2ZnZr precipitates is simple cubic (SC) with lattice parameter a=0.403 nm. The number density of Al2ZnZr precipitates in 7055-T7751 aluminum alloy is about 3.44×1011 mm-3. Moreover, there is a coherent relationship between Al2ZnZr with simple cubic (SC) structure and α(Al) with face centered cubic (FCC) structure, and the orientation relationship between them is , 〈001〉Al//〈001〉 .
Key words: 7055 aluminum alloy; Al2ZnZr; precipitate; orientation relationship; convergent beam electron diffraction(CBED); thin foil thickness; number density
