1420铝锂合金底遮板表面亮斑分析

Analysis of The Bright Spot on The Surface of 1420 Al-Li Alloy Bottom Cover Plate

为研究航天用1420铝锂合金底遮板表面产生异常亮斑的形成原因,对异常痕迹进行了组织分析、形貌观察、断口能谱分析、显微硬度测试、化学成分检测。结果表明:底遮板表面的异常痕迹贯穿壁厚,该区域组织成分异常,为光亮晶缺陷。结合底遮板所用原材料生产工艺分析,发现此光亮晶是1420铝锂合金铸锭在熔铸过程中形成的,属冶金类缺陷,在磷酸阳极化过程中,由于缺陷处膜层质量较差形成了宏观显现的亮斑。

In order to study the formation cause of abnormal bright spots on the surface of 1420 Al-Li alloy bottom cover plate for aerospace applications,the abnormal traces were analyzed by means of microstructure analysis,fracture morphology observation,energy dispersion spectrum analysis,micro-hardness test and chemical composition analysis.The results show that the abnormal traces on the surface of the bottom cover plate are bright crystalline defects which penetrate through the whole plate.The microstructure and composition of the traces are abnormal.Considering the production process of the bottom cover plate,the bright crystalline defects are formed during the melting of 1420 aluminum-lithium alloy ingots,which are metallurgical defects.Due to the poor quality of the film layer in the defect section,the bright spots are formed during the process of phosphoric acid anodizing.