Microstructure evolution of A380 aluminum alloy during rheological process under applied pressure  

作　　者：Ying Wang Shu-ming Xing Xiao-hui Ao Ting-yue Wang 

机构地区：[1]School of Mechanical,Electronic and Control Engineering,Beijing Jiaotong University,Beijing 100044,China [2]School of Mechanical Engineering,Beijing Institute of Technology,Beijing 100081,China

出　　处：《China Foundry》2019年第6期371-379,共9页中国铸造（英文版）

基　　金：National Natural Science Foundation of China(No.51275031).

摘　　要：In squeeze casting process,the essence of mold-filling and feeding is rheological solidification of the alloy melt under pressure.Microstructure evolution is inevitable in this process,which affects the mold-filling and feeding in turn.In this work,the Archimedes spiral sample prepared by indirect squeeze casting was applied to investigate the microstructure evolution during the rheological process under pressure.The results showed that the primaryα-Al phase was transformed from fine rosette-like or granular structure to coarse platelet-like structure with the increase of spiral length.However,the primaryα-Al grain size of the starting point had a slight growing trend compared with that at the position of 140 mm away from the starting point.The volume fraction of the primaryα-Al phase increased from 45.57%to 70.35%along the spiral length direction,demonstrating that the experimental pressure improved the rheological ability of the alloy melt to some extent.Furthermore,the eutectic Si phase was varied from a fine granular or wormlike structure to a coarse platelet-like or needle-like structure,and the dispersion of eutectic Si particles was also varied along the spiral length direction.This microstructure evolution was mainly owing to the comprehensive action of rheological solidification and pressurized solidification.More specifically,the microstructure evolution strongly depended on the pressure and rheological velocity during the rheological process,however,the effect of rheological distance was relatively small.In squeeze casting process, the essence of mold-filling and feeding is rheological solidification of the alloy melt under pressure. Microstructure evolution is inevitable in this process, which affects the mold-filling and feeding in turn. In this work, the Archimedes spiral sample prepared by indirect squeeze casting was applied to investigate the microstructure evolution during the rheological process under pressure. The results showed that the primary α-Al phase was transformed from fine rosette-like or granular structure to coarse platelet-like structure with the increase of spiral length. However, the primary α-Al grain size of the starting point had a slight growing trend compared with that at the position of 140 mm away from the starting point. The volume fraction of the primary α-Al phase increased from 45.57% to 70.35% along the spiral length direction, demonstrating that the experimental pressure improved the rheological ability of the alloy melt to some extent. Furthermore, the eutectic Si phase was varied from a fine granular or wormlike structure to a coarse platelet-like or needle-like structure, and the dispersion of eutectic Si particles was also varied along the spiral length direction. This microstructure evolution was mainly owing to the comprehensive action of rheological solidification and pressurized solidification. More specifically, the microstructure evolution strongly depended on the pressure and rheological velocity during the rheological process, however, the effect of rheological distance was relatively small.

关 键 词：microstructure evolution primaryα-Al EUTECTIC Si RHEOLOGICAL SOLIDIFICATION pressurized SOLIDIFICATION 

分 类 号：TG146.21[一般工业技术—材料科学与工程]