Clarifying the formation of equiaxed grains and microstructural refinement in the additive manufacturing of Ti-Cu

Controlling microstructural evolution in metallic additive manufacturing (AM) is difficult, especially in producing refined as-built grains instead of coarse, directional grains. Traditional solutions involve adding inoculants to AM feedstocks, but titanium (Ti) alloys cannot employ this approach wi...

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Main Authors: Alec I. Saville, Adriana Eres-Castellanos, Andrew B. Kustas, Levi Van Bastian, Donald F. Susan, Dale E. Cillessen, Sven C. Vogel, Natalie A. Compton, Kester D. Clarke, Alain Karma, Amy J. Clarke
Format: Article
Language:English
Published: Elsevier 2024-12-01
Series:Materials & Design
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Online Access:http://www.sciencedirect.com/science/article/pii/S0264127524008153
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author Alec I. Saville
Adriana Eres-Castellanos
Andrew B. Kustas
Levi Van Bastian
Donald F. Susan
Dale E. Cillessen
Sven C. Vogel
Natalie A. Compton
Kester D. Clarke
Alain Karma
Amy J. Clarke
author_facet Alec I. Saville
Adriana Eres-Castellanos
Andrew B. Kustas
Levi Van Bastian
Donald F. Susan
Dale E. Cillessen
Sven C. Vogel
Natalie A. Compton
Kester D. Clarke
Alain Karma
Amy J. Clarke
author_sort Alec I. Saville
collection DOAJ
description Controlling microstructural evolution in metallic additive manufacturing (AM) is difficult, especially in producing refined as-built grains instead of coarse, directional grains. Traditional solutions involve adding inoculants to AM feedstocks, but titanium (Ti) alloys cannot employ this approach without producing detrimental secondary phases. Ti-Cu (Ti-copper) alloys offer a solution through constitutional supercooling and/or solid state thermal cycling under AM conditions. This work analyzes a compositionally graded directed energy deposition (DED) Ti-Cu build, single-melt laser tracks, and dilatometric heat treatments to evaluate if, when, and by what mechanism(s) microstructural refinement occurs. Refinement by inoculation of unmelted powder particles was also considered. Constitutional supercooling produced no net microstructural refinement as any equiaxed dendrites which form are remelted with new deposition. This finding agreed with solidification modeling of powder bed fusion-laser beam (PBF-LB) and DED builds. Solid state thermal cycling refined microstructures only during ex-situ dilatometric heat treatments, suggesting build parameter optimization is needed to achieve refinement in-situ. Accidental heterogeneous nucleation on unmelted Ti powder, originating from the different thermophysical properties of Ti and Cu, provided the most significant microstructural refinement. This work systematically assesses the microstructural refinement mechanisms of Ti-Cu in AM builds and offers insights into microstructural control in eutectoid alloys.
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spelling doaj-art-9bfbbad9fe7e428fae619797f39f2abc2025-08-20T01:57:00ZengElsevierMaterials & Design0264-12752024-12-0124811344010.1016/j.matdes.2024.113440Clarifying the formation of equiaxed grains and microstructural refinement in the additive manufacturing of Ti-CuAlec I. Saville0Adriana Eres-Castellanos1Andrew B. Kustas2Levi Van Bastian3Donald F. Susan4Dale E. Cillessen5Sven C. Vogel6Natalie A. Compton7Kester D. Clarke8Alain Karma9Amy J. Clarke10Colorado School of Mines, 1500 Illinois Street, Golden, CO, 80401, United States; National Institute of Standards and Technology, 325 Broadway, Boulder, CO, 80305, United States; Corresponding author.Colorado School of Mines, 1500 Illinois Street, Golden, CO, 80401, United StatesSandia National Laboratory, 1611 Innovation Parkway SE, Albuquerque, NM, 87123, United StatesSandia National Laboratory, 1611 Innovation Parkway SE, Albuquerque, NM, 87123, United StatesSandia National Laboratory, 1611 Innovation Parkway SE, Albuquerque, NM, 87123, United StatesSandia National Laboratory, 1611 Innovation Parkway SE, Albuquerque, NM, 87123, United StatesLos Alamos National Laboratory, Los Alamos, NM, 87545, United StatesColorado School of Mines, 1500 Illinois Street, Golden, CO, 80401, United StatesColorado School of Mines, 1500 Illinois Street, Golden, CO, 80401, United States; Los Alamos National Laboratory, Los Alamos, NM, 87545, United StatesNortheastern University, Boston, MA, 02115, United StatesColorado School of Mines, 1500 Illinois Street, Golden, CO, 80401, United States; Los Alamos National Laboratory, Los Alamos, NM, 87545, United StatesControlling microstructural evolution in metallic additive manufacturing (AM) is difficult, especially in producing refined as-built grains instead of coarse, directional grains. Traditional solutions involve adding inoculants to AM feedstocks, but titanium (Ti) alloys cannot employ this approach without producing detrimental secondary phases. Ti-Cu (Ti-copper) alloys offer a solution through constitutional supercooling and/or solid state thermal cycling under AM conditions. This work analyzes a compositionally graded directed energy deposition (DED) Ti-Cu build, single-melt laser tracks, and dilatometric heat treatments to evaluate if, when, and by what mechanism(s) microstructural refinement occurs. Refinement by inoculation of unmelted powder particles was also considered. Constitutional supercooling produced no net microstructural refinement as any equiaxed dendrites which form are remelted with new deposition. This finding agreed with solidification modeling of powder bed fusion-laser beam (PBF-LB) and DED builds. Solid state thermal cycling refined microstructures only during ex-situ dilatometric heat treatments, suggesting build parameter optimization is needed to achieve refinement in-situ. Accidental heterogeneous nucleation on unmelted Ti powder, originating from the different thermophysical properties of Ti and Cu, provided the most significant microstructural refinement. This work systematically assesses the microstructural refinement mechanisms of Ti-Cu in AM builds and offers insights into microstructural control in eutectoid alloys.http://www.sciencedirect.com/science/article/pii/S0264127524008153Ti-CuConstitutional supercoolingDirected energy depositionLaser powder bed fusionMicrostructural refinement
spellingShingle Alec I. Saville
Adriana Eres-Castellanos
Andrew B. Kustas
Levi Van Bastian
Donald F. Susan
Dale E. Cillessen
Sven C. Vogel
Natalie A. Compton
Kester D. Clarke
Alain Karma
Amy J. Clarke
Clarifying the formation of equiaxed grains and microstructural refinement in the additive manufacturing of Ti-Cu
Materials & Design
Ti-Cu
Constitutional supercooling
Directed energy deposition
Laser powder bed fusion
Microstructural refinement
title Clarifying the formation of equiaxed grains and microstructural refinement in the additive manufacturing of Ti-Cu
title_full Clarifying the formation of equiaxed grains and microstructural refinement in the additive manufacturing of Ti-Cu
title_fullStr Clarifying the formation of equiaxed grains and microstructural refinement in the additive manufacturing of Ti-Cu
title_full_unstemmed Clarifying the formation of equiaxed grains and microstructural refinement in the additive manufacturing of Ti-Cu
title_short Clarifying the formation of equiaxed grains and microstructural refinement in the additive manufacturing of Ti-Cu
title_sort clarifying the formation of equiaxed grains and microstructural refinement in the additive manufacturing of ti cu
topic Ti-Cu
Constitutional supercooling
Directed energy deposition
Laser powder bed fusion
Microstructural refinement
url http://www.sciencedirect.com/science/article/pii/S0264127524008153
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