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采用真空感应熔炼法制备一种大型镍基高温合金铸件。对铸件本体取完整的横截面进行宏观腐蚀,并利用OM、SEM和EDS对截面不同区域进行显微组织分析。结果表明:铸件截面的宏观组织区域分为激冷晶区、柱状晶区、等轴晶区和心部细晶区。激冷晶区富集初生M_6C碳化物,其体积分数高达40.2%。等轴晶、心部细晶和柱状晶区,M_6C体积分数显著减少,分别为6.5%,1.3%和0。在上述不同区域,M_6C的成分相对固定,为73.8%~78.5%的W,其他为少量的Ni、Co、Cr。M_6C碳化物富含Nb、Ta和Ti,靠近冒口区W含量略高。共晶γ’成分稳定,不同区域无明显差异。
Preparation of a large nickel base superalloy casting by vacuum induction melting. The complete cross-section of the cast body was macro-corroded, and the microstructure of different sections of the cross-section was analyzed by OM, SEM and EDS. The results show that the macrostructure of the cast section is divided into chilled zone, columnar zone, equiaxed zone and fine heart zone. The chilled crystal area enriches the primary M_6C carbides with a volume fraction of up to 40.2%. Equiaxed grains, fine core grains and columnar grains, the volume fraction of M_6C decreased significantly, which was 6.5%, 1.3% and 0 respectively. In the above-mentioned different regions, the composition of M_6C is relatively fixed, ranging from 73.8% to 78.5% W, while others are small amounts of Ni, Co and Cr. M_6C carbides are rich in Nb, Ta and Ti, slightly higher in the riser zone. Eutectic γ ’composition is stable, no significant difference in different regions.