(中南大学 材料科学与工程学院，长沙 410083)
摘 要: 采用X射线衍射(XRD)、电子探针(EPMA)、扫描电子显微镜(SEM)和X射线光电子能谱(XPS)研究挤压前后Mg-10Li-5Al-0.02Zr合金的微观组织及合金在3.5% NaCl(质量分数)溶液中的析氢和电化学腐蚀行为，并分析腐蚀膜结构。结果表明：Mg-Li-Al-Zr合金热挤压后物相由α-Mg相、不规则的AlLi相、弥散的MgLi2Al和β-Li基体组成。热挤压后，合金组织均匀，晶粒细化，第二相数量减少。铸态和挤压态样品的腐蚀速率(PH)分别为(2.74±0.2) mm/a和(1.47±0.2) mm/a，沿挤压方向形成的不连续带状组织和均匀组织减弱微电偶腐蚀，提高合金的耐蚀性。挤压态Mg-Li-Al-Zr合金在NaCl溶液中浸泡时，表面形成一层较致密的腐蚀表面膜，其由Mg(OH)2、LiOH、Li2CO3和MgO构成。
关键字: 镁锂合金；电化学测试；腐蚀行为
（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
