Al-Zn-Mg-Cu合金塊體材料
(1. 北京科技大學(xué) 新金屬材料國(guó)家重點(diǎn)實(shí)驗(yàn)室，北京 100083;
2. 北京有色金屬研究總院， 北京 100088)
摘 要: 利用液氮球磨和真空熱壓技術(shù)制備納米晶Al-10Zn-3Mg-1.8Cu(質(zhì)量分?jǐn)?shù), ％)合金塊體材料。 采用X射線衍射(XRD)和透射電鏡(TEM)對(duì)材料在制備過(guò)程中的固態(tài)相變、 晶粒尺寸和熱穩(wěn)定性進(jìn)行分析。 結(jié)果表明， 材料經(jīng)過(guò)液氮球磨15 h后晶粒尺寸為37 nm， 真空熱壓后材料晶粒保持在100 nm， 熱擠壓后晶粒尺寸約為300 nm， 熱處理后晶粒尺寸保持不變。 材料的高熱穩(wěn)定性原因在于大量合金元素和雜質(zhì)元素超飽和固溶于Al基體中阻止了晶粒的長(zhǎng)大， 以及細(xì)小析出MgZn2相和Al2O3顆粒對(duì)于晶界的釘扎作用。
關(guān)鍵字: 低溫球磨； 納米晶塊體材料； Al-Zn-Mg-Cu合金； 熱穩(wěn)定性
TIAN Xiao-feng2, ZHANG Ji-shan1
（1. State Key Laboratory for Advanced Metals and Materials,
University of Science and Technology Beijing, Beijing 100083, China;
2. Beijing General Research Institute for Nonferrous Metals,
Beijing 100088, China）
Abstract: The preparation of bulk nanocrystalline Al-10Zn-3Mg-1.8Cu (mass fraction, %) alloy by mechanically milling at cryogenic temperature (cryomilling) and hot pressing in vacuum was studied. By X-ray diffraction (XRD) and transmission electron microscopy (TEM), the effects of cryomilling process on the phase transformations in solid, the grain size and the thermal stability for this alloy were investigated. The results show that the grain size of the as-atomized Al-Zn-Mg-Cu alloy powder is gradually reduced and approaches 37 nm after 15 h cryomilling. The average grain size reaches about 100 nm after hot pressing in vacuum. After hot extrusion and heat treatment, the grains grow to about 300 nm. The results obtained herein suggest that the significant thermal stability of the bulk nanocrystalline Al-Zn-Mg-Cu alloy may be attributed to the solute drag of the alloy elements and the impurity elements, which can prevent the grain growth. And more, the zener pinning from grain boundary of the nano-scale Al2O3 arising from cryomilling and the fine MgZn2 phase also play an important role.
Key words: cryomilling; bulk nanocrystalline materials; Al-Zn-Mg-Cu alloy; thermal stability
