TY - JOUR
T1 - Grain boundary network evolution in Inconel 718 from selective laser melting to heat treatment
AU - Holland, Sharniece
AU - Wang, Xiaoqing
AU - Fang, X. Y.
AU - Guo, Y. B.
AU - Yan, Feng
AU - Li, Lin
N1 - Publisher Copyright:
© 2018 Elsevier B.V.
PY - 2018/5/16
Y1 - 2018/5/16
N2 - Inconel 718 fabricated by selective laser melting (SLM) was used to investigate the evolution of grain boundary (GB) network structures from as-SLM to heat-treated (HT) samples. Using electron backscatter diffraction (EBSD) data and percolation theory based cluster analysis, GB character distribution and GB network topological metrics were computed at different build locations and directions. The microstructures of the as-SLM samples reveal large spatial heterogeneity in grain morphology and are dominated by general GBs (i.e., ∑> 29), which form one connected cluster spanning across the whole GB network. Heat-treatment homogenizes the microstructure and leads to the formation of annealing twins as a result of recrystallization, which dramatically increases the number of special boundaries (mainly twin ∑3 and twin-related ∑9, ∑27 boundaries with ~ 60% in boundary length fraction). However, these special boundaries have not yet fully connected/merged to form a percolated path throughout the GB network. The triple junction distributions of the HT sample are dominated by J1-type that consists of one special and two general boundaries, further confirming the interweaving GB network made of the general and special boundary clusters. In addition, the implication of applying GB engineering to the SLMed parts is discussed based on the comparison of GB network structures between the SLMed alloys and the conventionally GB engineered metals and alloys.
AB - Inconel 718 fabricated by selective laser melting (SLM) was used to investigate the evolution of grain boundary (GB) network structures from as-SLM to heat-treated (HT) samples. Using electron backscatter diffraction (EBSD) data and percolation theory based cluster analysis, GB character distribution and GB network topological metrics were computed at different build locations and directions. The microstructures of the as-SLM samples reveal large spatial heterogeneity in grain morphology and are dominated by general GBs (i.e., ∑> 29), which form one connected cluster spanning across the whole GB network. Heat-treatment homogenizes the microstructure and leads to the formation of annealing twins as a result of recrystallization, which dramatically increases the number of special boundaries (mainly twin ∑3 and twin-related ∑9, ∑27 boundaries with ~ 60% in boundary length fraction). However, these special boundaries have not yet fully connected/merged to form a percolated path throughout the GB network. The triple junction distributions of the HT sample are dominated by J1-type that consists of one special and two general boundaries, further confirming the interweaving GB network made of the general and special boundary clusters. In addition, the implication of applying GB engineering to the SLMed parts is discussed based on the comparison of GB network structures between the SLMed alloys and the conventionally GB engineered metals and alloys.
KW - Grain boundary
KW - Grain boundary engineering
KW - Inconel 718
KW - Microstructure
KW - Network
KW - Selective laser melting
UR - https://www.scopus.com/pages/publications/85045713906
U2 - 10.1016/j.msea.2018.04.045
DO - 10.1016/j.msea.2018.04.045
M3 - Article
AN - SCOPUS:85045713906
SN - 0921-5093
VL - 725
SP - 406
EP - 418
JO - Materials Science and Engineering A
JF - Materials Science and Engineering A
ER -