Abstract
The microstructure and superelasticity in additive manufactured NiTi shape memory alloys (SMAs) were investigated. Using elementally blended Ni and Ti powder feedstock, Ni-rich build coupons were fabricated via the laser-based directed energy deposition (LDED) technique. The build volumes were large enough to extract tensile and compressive test specimens from selected locations for spatially resolving microconstituents and the underlying stress-induced martensitic phase transformation (SIMT) morphology. In the as-deposited condition, X-ray diffraction identified the B2 atomic crystal structure of the austenitic parent phase in NiTi SMAs, and Ni4Ti3 precipitates were the predominant microconstituent identified through scanning electron microscopy. The microstructure exhibited anisotropy, which was characterized by the Ni4Ti3 precipitate morphology being coarsest nearest the substrate, while a finer morphology was observed farthest from the substrate. In-situ full-field deformation measurements calculated using digital image correlation confirmed that the SIMT predominately occurred in the finer precipitate morphology. Heat treatment reduced the degree of anisotropy, and DIC analysis revealed localized SIMT strains increased compared to the as-deposited condition.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 125-134 |
| Number of pages | 10 |
| Journal | Materials Science and Engineering A |
| Volume | 674 |
| DOIs | |
| State | Published - Sep 30 2016 |
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All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Condensed Matter Physics
- Mechanics of Materials
- Mechanical Engineering
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Anisotropic microstructure and superelasticity of additive manufactured NiTi alloy bulk builds using laser directed energy deposition. / Bimber, Beth A.; Hamilton, Reginald Felix; Keist, Jayme Scot; Palmer, Todd.
In: Materials Science and Engineering A, Vol. 674, 30.09.2016, p. 125-134.Research output: Contribution to journal › Article
TY - JOUR
T1 - Anisotropic microstructure and superelasticity of additive manufactured NiTi alloy bulk builds using laser directed energy deposition
AU - Bimber, Beth A.
AU - Hamilton, Reginald Felix
AU - Keist, Jayme Scot
AU - Palmer, Todd
PY - 2016/9/30
Y1 - 2016/9/30
N2 - The microstructure and superelasticity in additive manufactured NiTi shape memory alloys (SMAs) were investigated. Using elementally blended Ni and Ti powder feedstock, Ni-rich build coupons were fabricated via the laser-based directed energy deposition (LDED) technique. The build volumes were large enough to extract tensile and compressive test specimens from selected locations for spatially resolving microconstituents and the underlying stress-induced martensitic phase transformation (SIMT) morphology. In the as-deposited condition, X-ray diffraction identified the B2 atomic crystal structure of the austenitic parent phase in NiTi SMAs, and Ni4Ti3 precipitates were the predominant microconstituent identified through scanning electron microscopy. The microstructure exhibited anisotropy, which was characterized by the Ni4Ti3 precipitate morphology being coarsest nearest the substrate, while a finer morphology was observed farthest from the substrate. In-situ full-field deformation measurements calculated using digital image correlation confirmed that the SIMT predominately occurred in the finer precipitate morphology. Heat treatment reduced the degree of anisotropy, and DIC analysis revealed localized SIMT strains increased compared to the as-deposited condition.
AB - The microstructure and superelasticity in additive manufactured NiTi shape memory alloys (SMAs) were investigated. Using elementally blended Ni and Ti powder feedstock, Ni-rich build coupons were fabricated via the laser-based directed energy deposition (LDED) technique. The build volumes were large enough to extract tensile and compressive test specimens from selected locations for spatially resolving microconstituents and the underlying stress-induced martensitic phase transformation (SIMT) morphology. In the as-deposited condition, X-ray diffraction identified the B2 atomic crystal structure of the austenitic parent phase in NiTi SMAs, and Ni4Ti3 precipitates were the predominant microconstituent identified through scanning electron microscopy. The microstructure exhibited anisotropy, which was characterized by the Ni4Ti3 precipitate morphology being coarsest nearest the substrate, while a finer morphology was observed farthest from the substrate. In-situ full-field deformation measurements calculated using digital image correlation confirmed that the SIMT predominately occurred in the finer precipitate morphology. Heat treatment reduced the degree of anisotropy, and DIC analysis revealed localized SIMT strains increased compared to the as-deposited condition.
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U2 - 10.1016/j.msea.2016.07.059
DO - 10.1016/j.msea.2016.07.059
M3 - Article
AN - SCOPUS:84982845589
VL - 674
SP - 125
EP - 134
JO - Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing
JF - Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing
SN - 0921-5093
ER -