Effect of cooling rates on dendrite spacings of directionally solidified DZ125 alloy under high ther

• 作 者: ZHANG Weiguo LIU Lin ZHAO Xinbao HUANG Taiwen YU Zhuhuan QU Min FU Hengzhi
• 机 构: State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 7100
• 出 处: 稀有金属（英文版）
• 发表日期: 2009年6期
• 关键词: directional solidification superalloy thermal gradient cooling rote dendrite arm

The dendrite morphologies and spacings of directionally solidified DZ125 superalloy were investigated under high thermal gradient about 500 K/cm. The results reveal that, with increasing cooling rate, both the spacings of primary and secondary dendrite arms decrease, and the dendrite morphologies transit from coarse to superfine dendrite. The secondary dendrite arms trend to be refined and be well developed, and the tertiary dendrite will occur. The predictions of the Kurz/Fisher model and the Hunt/Lu model accord basically with the experimental data for primary dendrite arm spacing. The regression equation of the primary dendrite arm spacings λ_1 and the cooling rate V_c is λ_1=0.013V_c~(-0.32). The regression equation of the secondary dendrite arm spacing λ_2 and the cooling rate V_c is λ_2=0.00258V_c~(-0.31), which gives good agreement with the Feurer/Wunderlin model.