TY - JOUR
T1 - Role of alloy composition on micro-cracking mechanisms in additively manufactured Ni-based superalloys
AU - Chakraborty, Apratim
AU - Muhammad, Waqas
AU - Masse, Jean Philippe
AU - Tangestani, Reza
AU - Ghasri-Khouzani, Morteza
AU - Wessman, Andrew
AU - Martin, Étienne
N1 - Funding Information:
The authors are thankful to Natural Sciences and Engineering Research Council of Canada (NSERC) under grant no. CRDPJ 533406-18 and Amber Andreaco, working in the material supply division at GE Additive, for supporting this work. Étienne Martin is thankful to the Jacques L’Écuyer Industrial Research Chair Foundation.
Publisher Copyright:
© 2023 Acta Materialia Inc.
PY - 2023/8/15
Y1 - 2023/8/15
N2 - Inherent micro-cracking mechanisms in two contrasting high-gamma-prime (high-γ’) Ni-based superalloys processed by laser powder bed fusion (LPBF) were investigated. RENÉ 65 (R65) has a 42% γ’ volume fraction including Al, Ti, and Nb, while RENÉ 108 (R108) has a higher γ’ volume fraction (63%) including Al, Ta, and lesser Ti. Quantitative analysis showed R108 exhibits 329% higher micro-cracking density than R65. All micro-cracks propagate along high angle boundaries (HABs) and exhibit interdendritic morphologies suggesting solidification cracking is the dominant micro-cracking mechanism. Moreover, secondary phases detrimental for solid-state cracking are not observed at the HABs. Atom probe tomography (APT) showed preferential segregation of Hf, Mo, C, B at the R108 HAB and Zr, Ti, Mo, C, B at the R65 HAB. The Kou solidification cracking criterion showed that Hf and Zr partitioning along the grain boundaries increases micro-cracking susceptibility. Gamma prime did not form during the LPBF process and titanium has a higher tendency than tantalum to partition in the last liquid to solidify.
AB - Inherent micro-cracking mechanisms in two contrasting high-gamma-prime (high-γ’) Ni-based superalloys processed by laser powder bed fusion (LPBF) were investigated. RENÉ 65 (R65) has a 42% γ’ volume fraction including Al, Ti, and Nb, while RENÉ 108 (R108) has a higher γ’ volume fraction (63%) including Al, Ta, and lesser Ti. Quantitative analysis showed R108 exhibits 329% higher micro-cracking density than R65. All micro-cracks propagate along high angle boundaries (HABs) and exhibit interdendritic morphologies suggesting solidification cracking is the dominant micro-cracking mechanism. Moreover, secondary phases detrimental for solid-state cracking are not observed at the HABs. Atom probe tomography (APT) showed preferential segregation of Hf, Mo, C, B at the R108 HAB and Zr, Ti, Mo, C, B at the R65 HAB. The Kou solidification cracking criterion showed that Hf and Zr partitioning along the grain boundaries increases micro-cracking susceptibility. Gamma prime did not form during the LPBF process and titanium has a higher tendency than tantalum to partition in the last liquid to solidify.
KW - Additive manufacturing
KW - Alloy composition
KW - Cracking
KW - Laser powder bed fusion
KW - Superalloys
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U2 - 10.1016/j.actamat.2023.119089
DO - 10.1016/j.actamat.2023.119089
M3 - Article
AN - SCOPUS:85162920212
SN - 1359-6454
VL - 255
JO - Acta Materialia
JF - Acta Materialia
M1 - 119089
ER -