显微组织的非均匀性对AA2099-T8铝锂合金局部-中国有色金属学报.PDFVIP

25 3 2015 3 Volume 25 Number 3 The Chinese Journal of Nonferrous Metals March 2015 1004-0609(2015)-03-0611-07 AA2099-T8 ( 400054) AA2099-T8 3.5%NaCl( ) (SLC) T (Al CuLi) 1 2 AA2099-T8 TG113.23+1 A Effect of microstructural heterogeneity on localized corrosion of AA2099-T8 aluminum-lithium alloy MA Yan-long, MENG Xiao-min, HUANG Wei-jiu, ZHANG Xiao-bin (College of Materials Science and Engineering, Chongqing University of Technology, Chongqing 400054, China) Abstract: The influence of microstructure on localized corrosion of the AA2099-T8 aluminum-lithium alloy was investigated using electrochemistry and scanning electron microscopy. The result shows that the microstructure of the alloy is not uniform and high densities of dislocations and slip bands are found within some of the grains. The micro-galvanic coupling between coarse second phase particles and aluminum matrix leads to mild pitting corrosion and the corrosion behavior is related to the types of the phase particles. Severe localized corrosion (SLC) is associated with heterogeneous plastic deformation and preferential precipitation during aging. Heterogeneous plastic deformation induces that population density of dislocations increases and number or volume fraction of the electrochemically active T (Al CuLi) phase consequently increases after artificial aging, resulting in increased corrosion susceptibility in local 1 2 regions which leads to SLC.