(北京航空材料研究院，北京 100095)
摘 要: 采用低溫球磨、熱等靜壓和擠壓等工藝制備塊體納米晶純鋁。分別采用透射電鏡(TEM)和差熱分析(DSC)對(duì)塊體納米晶純鋁的微觀組織和熱穩(wěn)定性進(jìn)行研究，并對(duì)所制備的塊體納米晶純鋁的化學(xué)成分、密度、硬度和拉伸性能進(jìn)行測(cè)定，借助掃描電鏡(SEM)對(duì)塊體納米晶純鋁的拉伸斷口進(jìn)行觀察。同時(shí)，分別依據(jù)Hall-Petch公式、Orowan機(jī)制和Taylor公式定量估算細(xì)晶強(qiáng)化、彌散強(qiáng)化和位錯(cuò)強(qiáng)化對(duì)塊體納米晶純鋁屈服強(qiáng)度的獨(dú)立貢獻(xiàn)。結(jié)果表明：所制備的塊體納米晶純鋁的平均晶粒尺寸約為300 nm，密度為2.692 g/cm3，顯微硬度為109.15HV；塊體納米晶純鋁的屈服強(qiáng)度和抗拉強(qiáng)度分別達(dá)270 MPa和379 MPa，伸長(zhǎng)率為3.2%；塊體納米晶純鋁的高強(qiáng)度主要可歸因于細(xì)晶強(qiáng)化和彌散強(qiáng)化。
關(guān)鍵字: 納米晶；純鋁；低溫球磨；微觀組織；力學(xué)性能；強(qiáng)化機(jī)理
（Beijing Institute of Aeronautical Materials , Beijing 100095, China）
Abstract:The combination of three processing routes of cryomilling, hot isotropic pressing (HIP) and hot extrusion was employed for the fabrication of the bulk nanocrystalline Al. The microstructure and thermal stability of the bulk nanocrystalline Al were studied by transmission electron microscopy (TEM) and differential scanning calorimetry (DSC), respectively. The chemical composition, density, microhardness and tensile property of the bulk nanocrystalline Al were also measured. Besides, the tensile fracture surface of the bulk nanocrystalline Al was observed by scanning electron microscopy (SEM). Furthermore, the contributions of grain-size effect, Orowan strengthening and dislocation strengthening to the yield strength of the bulk nanocrystalline Al were quantitatively estimated by Hall-Petch, Orowan and Taylor equations, separately. The results demonstrate that the average grain size of the bulk nanocrystalline Al is approximately 300 nm. The density and microhardness of the bulk nanocrystalline Al are 2.692 g/cm3 and 109.15HV, respectively. The resulted sample exhibits super high yield strength of 270 MPa and ultimate strength of 379 MPa with an elongation of 3.2%. The enhanced strength of the bulk nanocrystalline Al can be mainly attributed to the grain-size effect and Orowan strengthening.
Key words: nanocrystalline; aluminum; cryomilling; microstructure; mechanical properties; strengthening mechanism
