微观组织对一种超轻高强镁锂合金耐蚀性的影响
Effect of Microstructure on Corrosion Resistance of a High-strength Ultralightweight Mg-Li Alloy
谢云 1刘婷 1王雯 1周佳琳 1唐颂2
作者信息
- 1. 南昌航空大学材料科学与工程学院 南昌 330063
- 2. 南京理工大学材料科学与工程学院 南京 210094
- 折叠
摘要
借助X射线衍射(XRD)和扫描电子显微镜(SEM)研究了铸态Mg-15Li-6Al合金以及固溶处理后分别进行空冷和水冷等3种不同处理方式获得合金的相组成和形貌特征.采用浸泡实验和电化学实验对比研究了这3种不同状态合金在3.5％NaCl水溶液中的腐蚀行为.结果表明:3种不同状态合金的主要基体组织均为β-Li,且从铸态、固溶空冷态到固溶水冷态,合金中AlLi析出相逐渐减少,固溶水冷态合金基本由单相β-Li组成.3种不同状态合金耐蚀性由低到高的顺序为:铸态＜固溶空冷态＜固溶水冷态,且固溶水冷态合金相比铸态合金的腐蚀电位提高480 mV,腐蚀电流密度降低3个数量级.这主要是由于固溶处理使Al有效回溶到β-Li基体中,随后的快速冷却使AlLi相的析出受到抑制,减少了 AlLi与β-Li两相间腐蚀微电偶对的数量,提高了合金的耐蚀性.
Abstract
Mg-15Li-6Al alloy was prepared by vacuum induction melting and then the alloy was sub-jected to solution treatment plus air cooling or water cooling respectively.The phase constitution and mi-crostructure of the alloys(as-cast,solution treatment plus air cooling or water cooling),were analyzed by means of X-ray diffraction analysis(XRD)and scanning electron microscope(SEM).In addition,the cor-rosion behavior of the three alloys was studied by gravimetric and electrochemical tests.The results show that the three-state alloys are all mainly composed of β-Li with a little of second phase AlLi,and the fractions of secondary AlLi precipitates in the alloys decrease in the following order:as-cast,solution treatment+air cooling and solution treatment+water cooling.The alloy after solution treatment plus wa-ter cooling is almost composed of single β-Li phase.On the contrary,the corrosion resistance of the three alloys follows the sequence:as-cast＜solution treatment+air cooling＜solution treatment+water cool-ing.Relative to the as-cast alloy,the free corrosion potential increases by 480 mV and the corrosion cur-rent density decreases by three orders of magnitude for the alloy solution subjected to solution treatment plus water cooling.The solution treatment makes more Al to dissolve back into β-Li,and subsequent fast cooling strongly suppresses the precipitation of AlLi.Therefore,the number of micro galvanic couple of Al-Li and β-Li decreases,resulting in marked improvement of corrosion resistance.
关键词
镁锂合金/热处理/耐蚀性/显微组织Key words
Mg-Li alloys/heat treatment/corrosion resistance/microstructure引用本文复制引用
基金项目
国家自然科学基金青年基金(52101142)
江苏省自然科学基金青年基金(BK20200503)
江西省自然科学基金青年基金(20224BAB214018)
出版年
2024
NETL
NSTL
维普
万方数据