TY - JOUR
T1 - Comparative Investigation of the Undercooling Capacity and Single-Crystal Castability of Some Ni-Based Superalloys
AU - Ma, Dexin
AU - Zhao, Yunxing
AU - Xu, Weitai
AU - Xu, Fuze
AU - Wei, Jianhui
AU - Zhang, Haijie
N1 - Funding Information:
This research was funded by the Shenzhen Peacock Plan (KQTD2015032716463668) and by the Guangdong Innovative and Entrepreneurial Research Team Program (607264877417).
Publisher Copyright: © 2022 by the authors.
PY - 2023/1
Y1 - 2023/1
N2 - The undercooling capacity of a superalloy is an essential physical property to determine its single-crystal (SC) castability, because stray grains (SGs) will be formed if the geometrical undercooling established at the platform extremities exceeds the undercooling capacity of the applied alloy. In the present work, both the undercooling capacity of eight Ni-based superalloys and their SC castability were experimentally investigated. The liquidus temperature, the critical temperature for grain nucleation, and hence the undercooling capacities of the investigated alloys were evaluated based on the temperature evolution during the heating and cooling processes. The current experimental study revealed a significant difference in undercooling capacity for the superalloys. In the production of SC blade castings, the tendency to form SG defects was found to be highly related to the alloy’s undercooling capacity. The alloys having a low undercooling capacity of around 10 K were very prone to the formation of SGs. In comparison, the alloys with a moderate undercooling capacity from 20 K to 30 K could be easily cast into SC blades without SGs, exhibiting the best SC castability. Other factors influencing the SG formation were also analyzed. As a result, a criterion for the formation of geometry-related SG defects was proposed, in which the influence of the alloy undercooling capacity, casting geometry, and solidification condition are involved.
AB - The undercooling capacity of a superalloy is an essential physical property to determine its single-crystal (SC) castability, because stray grains (SGs) will be formed if the geometrical undercooling established at the platform extremities exceeds the undercooling capacity of the applied alloy. In the present work, both the undercooling capacity of eight Ni-based superalloys and their SC castability were experimentally investigated. The liquidus temperature, the critical temperature for grain nucleation, and hence the undercooling capacities of the investigated alloys were evaluated based on the temperature evolution during the heating and cooling processes. The current experimental study revealed a significant difference in undercooling capacity for the superalloys. In the production of SC blade castings, the tendency to form SG defects was found to be highly related to the alloy’s undercooling capacity. The alloys having a low undercooling capacity of around 10 K were very prone to the formation of SGs. In comparison, the alloys with a moderate undercooling capacity from 20 K to 30 K could be easily cast into SC blades without SGs, exhibiting the best SC castability. Other factors influencing the SG formation were also analyzed. As a result, a criterion for the formation of geometry-related SG defects was proposed, in which the influence of the alloy undercooling capacity, casting geometry, and solidification condition are involved.
KW - blade casting
KW - single crystal
KW - stray grain
KW - superalloy
KW - undercooling capacity
UR - http://www.scopus.com/inward/record.url?scp=85146695203&partnerID=8YFLogxK
U2 - 10.3390/cryst13010057
DO - 10.3390/cryst13010057
M3 - Article
AN - SCOPUS:85146695203
SN - 2073-4352
VL - 13.2023
JO - Crystals
JF - Crystals
IS - 1
M1 - 57
ER -