Directionally solidified single crystal superalloy test bars were prepared by the spiral grain selection method. The microstructural evolution and orientation characteristics of the starter block and spiral part were studied, and the influence of the competitive growth of crystals on the microstructural characteristics was analyzed. The results show that the divergent grain groups, with small size and randomly oriented grains, appear at the bottom of the start block due to the chilling effect, which is an important area for competitive growth. As the height of the starter block increases, the primary dendrite spacing increases, and the grain density decreases; furthermore, the proportion of grains with an orientation deflection angle less than 10° gradually increases. The <001> texture gradually becomes stronger as the height of the starter block increases, which indicates that the competitive growth of crystals gradually weakens. At the initial stage of the crystal selection in the spiral part, the obstacle of adjacent grains and spiral passage is the main working mechanism. The grains located at the inner side of the front edge of the spiral passage have the growth advantage. The single crystal screening process is achieved at about two-thirds of the spiral height, and the single crystal with the orientation deviation angle of 6.7° from the casting axis is prepared.

Mang Xu;Xiao-qi Geng;Xiang-long Zhang;Guo-huai Liu;Ye Wang;Zhao-dong Wang;Jing-jie Guo

State Key Laboratory of Rolling and Automation,Northeastern University,Shenyang 110819,China;School of Materials Science and Engineering,Harbin University of Science and Technology,Harbin 150040,China;School of Materials Science and Engineering,Harbin Institute of Technology,Harbin 150001,China

中国铸造

[1]Mang Xu;Xiao-qi Geng;Xiang-long Zhang;Guo-huai Liu;Ye Wang;Zhao-dong Wang;Jing-jie Guo-.Effect of competitive crystal growth on microstructural characteristics of directionally solidified nickel-based single crystal superalloy)[J].中国铸造,2022(02):109-116

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