(中南大學(xué) 材料科學(xué)與工程學(xué)院，長(zhǎng)沙 410083)
摘 要: 采用X射線衍射(XRD)、電子探針(EPMA)、掃描電子顯微鏡(SEM)和X射線光電子能譜(XPS)研究擠壓前后Mg-10Li-5Al-0.02Zr合金的微觀組織及合金在3.5% NaCl(質(zhì)量分?jǐn)?shù))溶液中的析氫和電化學(xué)腐蝕行為，并分析腐蝕膜結(jié)構(gòu)。結(jié)果表明：Mg-Li-Al-Zr合金熱擠壓后物相由α-Mg相、不規(guī)則的AlLi相、彌散的MgLi2Al和β-Li基體組成。熱擠壓后，合金組織均勻，晶粒細(xì)化，第二相數(shù)量減少。鑄態(tài)和擠壓態(tài)樣品的腐蝕速率(PH)分別為(2.74±0.2) mm/a和(1.47±0.2) mm/a，沿?cái)D壓方向形成的不連續(xù)帶狀組織和均勻組織減弱微電偶腐蝕，提高合金的耐蝕性。擠壓態(tài)Mg-Li-Al-Zr合金在NaCl溶液中浸泡時(shí)，表面形成一層較致密的腐蝕表面膜，其由Mg(OH)2、LiOH、Li2CO3和MgO構(gòu)成。
關(guān)鍵字: 鎂鋰合金；電化學(xué)測(cè)試；腐蝕行為
（School of Materials Science and Engineering, Central South University, Changsha 410083, China）
Abstract:Microstructure of Mg-10Li-5Al-0.02Zr alloy and the effects of extrusion on hydrogen and electrochemical corrosion behavior of Mg-Li-Al-Zr alloy in 3.5% NaCl(mass fraction) solution and the corrosion film structure were studied by X-ray diffractometry(XRD), electron probe micro-analyze(EPMA), scanning electron microscopy(SEM) and X-ray photoelectron spectroscopy(XPS). The results indicate that the Mg-Li-Al-Zr alloy after extrusion consists mainly of α-Mg, irregular AlLi, dispersed MgLi2Al and β-Li phases. After extrusion, the structure of Mg-Li-Al-Zr alloy becomes more evenly, the grain size of Mg-Li-Al-Zr alloy refines, the number of second phases decreases. The average corrosion rates(PH) of Mg-Li-Al-Zr alloys before and after extrusion are (2.74±0.2) mm/a and (1.47±0.2) mm/a, respectively. A discontinuous banded structure forming along the extrusion direction and the uniform microstructure can weaken effectively micro-galvanic corrosion and increase corrosion resistance. After the extruded Mg-Li-Al-Zr alloy is immersed in NaCl solution, a dense and compact corrosion coating which consists mainly of Mg(OH)2, LiOH, Li2CO3 and MgO forms on the surface.
Key words: Mg-Li alloy; electrochemical measurement; corrosion behavior
