(中南大學(xué) 材料科學(xué)與工程學(xué)院，長(zhǎng)沙 410083)
摘 要: 借助超景深三維顯微鏡、掃描電鏡、能譜分析、透射電鏡、X射線物相分析、電化學(xué)測(cè)試等手段，對(duì)比不同Cu、Mg含量對(duì)2A12鋁合金化銑粗糙度的影響。結(jié)果表明：當(dāng)2A12鋁合金中的Cu含量或Mg含量位于成分上限時(shí)，化銑后的表面粗糙度達(dá)到3.4 μm，合金合理的成分配比為4.02%Cu+1.39%Mg(質(zhì)量分?jǐn)?shù))，化銑后的表面粗糙度為1.4 μm；θ和S的模擬相在化銑液中的電極電位較之Al基體更正，因而在電化學(xué)腐蝕過(guò)程中，θ相、S相充當(dāng)陰極，其周?chē)腁l基體會(huì)優(yōu)先發(fā)生腐蝕；合金在化銑時(shí)，隨著局部不均勻腐蝕的進(jìn)行，形成相凸起、腐蝕坑等表面形貌特征；尺寸為50 μm左右的大型腐蝕坑是造成表面粗糙度增大的主要原因，晶內(nèi)小尺寸的彌散T相(Al20Cu2Mn3)對(duì)化銑粗糙度的影響較小。
關(guān)鍵字: 2A12鋁合金；Cu含量；Mg含量；化銑；表面粗糙度；微觀組織；模擬相
（School of Materials Science and Engineering, Central South University, Changsha 410083, China）
Abstract:The effect of different Cu and Mg content on the surface roughness of 2A12 Al alloy after chemical milling was investigated by ultra-depth three-dimensional microscope, scanning electron microscope with energy dispersive X-ray spectroscopy, transmission electron microscope, X-ray diffraction analysis and electrochemical measurement. The results indicate that, when the Cu or Mg content in the alloy is at the upper limit of the composition, the surface roughness after milling is 3.4 μm. The reasonable distribution ratio of the alloy is 4.02%Cu+1.39%Mg (mass fraction). The surface roughness after milling is 1.4 μm. The corrosion potentials of the simulated θ phase and S phase in chemical milling solution are more positive than that of the Al matrix. During the electrochemical corrosion process, the θ phase and S phase act as cathodic zone and lead the Al matrix around them be preferentially corroded. Besides, the development of local nonuniform-corrosion results in phase protrusion and corrosion pit. The large-scale corrosion pit with a size of about 50 μm is the main cause to increase surface roughness, whereas, the small-sized intragranular dispersoid such as T-phase (Al20Cu2Mn3) has little influence on it.
Key words: 2A12 aluninum alloy; Cu content; Mg content; chemical milling; surface roughness; microstructure; simulated phase
