Influence of Dilute Hf Additions on Precipitation and Martensitic Transformation in Ni-Ti-Pd Alloys

Coppa, Anne C.; Kapoor, Monica; Hornbuckle, B.C.; Weaver, M.L.; Noebe, Ronald D.; Thompson, Gregory B.

doi:10.1007/s11837-015-1567-5

Cited by 4 publications

(2 citation statements)

References 30 publications

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“…Solute cluster analysis is a fundamental use of data mining in atom probe tomography (APT) aiding in the analysis of features such as nucleation sites, site-specific segregation, dispersants, dislocations, and precipitates. In many of these cases, isoconcentration surfaces have been employed to determine cluster compositions and generate particle size, density, inter-particle spacing, and composition (Coppa et al, 2015;Darling et al, 2015;Kapoor et al, 2017). From these isoconcentration surfaces, proximity histograms (or proxigrams) can be created to provide compositional profiles normal to these surfaces (Hellman et al, 2000(Hellman et al, , 2003Isheim et al, 2006), with a major advantage of a proxigram profile being able to accommodate curved surfaces.…”

Section: Introductionmentioning

confidence: 99%

The Influence of Isoconcentration Surface Selection in Quantitative Outputs from Proximity Histograms

et al. 2019

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Isoconcentration surfaces are commonly used to delineate phases in atom probe datasets. These surfaces then provide the spatial and compositional reference for proximity histograms, the number density of particles, and the volume fraction of particles within a multiphase system. This paper discusses the influence of the isoconcentration surface selection value on these quantitative outputs, using a simple oxide dispersive strengthened alloy, Fe91Ni8Zr1, as the case system. Zirconium reacted with intrinsic oxygen impurities in a consolidated ball-milled powder to precipitate nanoscale zirconia particles. The zirconia particles were identified by varying the Zr-isoconcentration values as well as by the maximum separation data mining method. The associated outputs mentioned above are elaborated upon in reference to the variation in this Zr isosurface value. Considering the dataset as a whole, a 10.5 at.% Zr isosurface provided a compositional inflection point for Zr between the particles and matrix on the proximity histogram; however, this value was unable to delineate all of the secondary oxide particles identified using the maximum separation method. Consequently, variations in the number density and volume fraction were observed as the Zr isovalue was changed to capture these particles resulting in a loss of the compositional accuracy. This highlighted the need for particle-by-particle analysis.

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Section: Introductionmentioning

confidence: 99%

The Influence of Isoconcentration Surface Selection in Quantitative Outputs from Proximity Histograms

et al. 2019

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“…Therefore, one of the key issues in researching Ti–Ni–Pd alloys is the improvement of resistance to permanent deformation upon actuation cycles at higher working temperature ranges. There have been various approaches to improve shape memory properties at higher temperatures such as (1) grain size refinement through severe plastic deformation [28], (2) the addition of quaternary elements [29,30,31] and (3) precipitation strengthening [25,32,33,34,35,36]. The combination of multiple strengthening mechanisms has been found to be effective for increasing strength and improving shape memory properties [37,38].…”

Section: Introductionmentioning

confidence: 99%

Effect of Stoichiometry on Shape Memory Properties and Functional Stability of Ti–Ni–Pd Alloys

et al. 2019

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Ti–Ni–Pd shape memory alloys are promising candidates for high-temperature actuators operating at above 373 K. One of the key issues in developing high-temperature shape memory alloys is the degradation of shape memory properties and dimensional stabilities because plastic deformation becomes more pronounced at higher working temperature ranges. In this study, the effect of the Ti:(Ni + Pd) atomic ratio in TixNi70−xPd30 alloys with Ti content in the range from 49 at.% to 52 at.% on the martensitic transformation temperatures, microstructures and shape memory properties during thermal cycling under constant stresses were investigated. The martensitic transformation temperatures decreased with increasing or decreasing Ti content from the stoichiometric composition. In both Ti-rich and Ti-lean alloys, the transformation temperatures decreased during thermal cycling and the degree of decrease in the transformation temperatures became more pronounced as the composition of the alloy departed from the stoichiometric composition. Ti2Pd and P phases were formed during thermal cycling in Ti-rich and Ti-lean alloys, respectively. Both Ti-rich and Ti-lean alloys exhibited superior dimensional stabilities and excellent shape memory properties with higher recovery ratio and larger work output during thermal cycling under constant stresses when compared with the alloys with near-stoichiometric composition.

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Phase Transformations and Microstructural Evolution: Part I

Clarke

2015

JOM

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Influence of Dilute Hf Additions on Precipitation and Martensitic Transformation in Ni-Ti-Pd Alloys

Cited by 4 publications

References 30 publications

The Influence of Isoconcentration Surface Selection in Quantitative Outputs from Proximity Histograms

The Influence of Isoconcentration Surface Selection in Quantitative Outputs from Proximity Histograms

Effect of Stoichiometry on Shape Memory Properties and Functional Stability of Ti–Ni–Pd Alloys

Phase Transformations and Microstructural Evolution: Part I

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