Effect of Withdrawal Rates on Microstructure and Creep Strength of a Single Crystal Superalloy Processed by LMC
Effect of Withdrawal Rates on Microstructure and Creep Strength of a Single Crystal Superalloy Processed by LMC
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DOI：
10.1016/s1005-0302(10)60050-3
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发表时间：
2010-04-01
影响因子：
10.9
通讯作者：
Lou, Langhong
中科院分区：
文献类型：
--
作者：
Liu, Chengbao;Shen, Jian;Lou, Langhong
采用液态金属冷却（LMC）工艺以不同的拉拔速率对镍基单晶（SC）高温合金进行定向凝固。随着拉拔速度从 3 毫米/分钟增加到 12 毫米/分钟，显微组织得到细化。然而，15 毫米/分钟的较高提拉速度会导致杂散晶粒的形成。发现共晶的尺寸和体积分数随着退出速率的增加而减小。在1250℃固溶热处理后，在样品中观察到未溶解的共晶。据观察，高温蠕变断裂寿命对这些剩余共晶的分数非常敏感。 1000 ℃/235 MPa 下的蠕变断裂试验表明，细化的微观结构和低含量的剩余共晶可显着提高断裂寿命。
A nickel base single crystal (SC) superalloy was directionally solidified using liquid metal cooling (LMC) process at various withdrawal rates. The microstructure was refined as increasing the withdrawal rate from 3 to 12 mm/min. However, higher withdrawal rate of 15 mm/min induced the formation of stray grains. Size and volume fraction of the eutectics were found to decrease with the increasing in withdrawal rate. After solution heat treatment at 1250 degrees C, un-dissolved eutectic was observed in specimens. High temperature creep rupture life was observed to be very sensitive to the fraction of these remaining eutectics. Creep rupture tests at 1000 degrees C/235 MPa showed that refined microstructure and low fraction of the remaining eutectic lead to significant improvement of the rupture life.