Chengbao Liu Jian Shen Jian Zhang Langhong Lou
材料科学技术（英）
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°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°C/235 MPa showed that refined microstructure and low fraction of the remaining eutectic lead to significant improvement of the rupture life.
关键词:
Eutectic
,
single crystal superalloy
,
liquid-metal-cooling
,
withdrawal rate
