arXiv subjects

Samuel Price

Publications and source records attributed to Samuel Price.

4 recordsLinked to original sources

arXiv2026

Two-step transient liquid phase bonding of NiTi to Ti-6Al-4V through a NbZrW barrier

Dissimilar joining of NiTi to Ti-6Al-4V (Ti-64) is limited by brittle Ti2Ni formation and degradation of NiTi functionality. A two-step transient liquid phase (TLP) route was developed in which a refractory NbZrW diffusion barrier converts the incompatible couple into two independently bondable interfaces. The barrier plays a different role for each alloy: a reactive substrate for NiTi, dissolving to form a Ti-rich Ni-Ti-Nb liquid that infiltrates its own grain boundaries and is terminated by selective Ti absorption into the barrier; and an inert substrate for Ti-64, joined through contact melting of a sacrificial Cu foil. Both interfaces are fully dense and free of continuous intermetallic layers. In tension, joints spanning both interfaces began transforming at 350 MPa, exhibited a stress plateau to 2.5 global strain (consistent with stress-induced transformation of the NiTi half of the gauge) and failed beyond the plateau at 380-410 MPa. Five load-unload cycles to 460 MPa showed stable superelastic loops with minor ratcheting. These results demonstrate that a diffusion barrier enables dissimilar TLP joining of otherwise incompatible alloys.

cond-mat.mtrl-sci↗

arXiv2026

Transient Liquid Phase Bonding of NiTi Using Cu- and Nb-base Interlayers

Transient liquid phase (TLP) bonding was examined as an approach for joining NiTi to achieve a high joint efficiency while minimizing chemical variance within the joint region. Two bonding interlayer chemistries (Cu-base and Nb-base) were identified by screening thermodynamic criteria for TLP in ternary alloys using the CALPHAD method. These two systems were then experimentally evaluated with respect to their impact on solidification kinetics, microstructure in the joint region, and performance during quasistatic and cyclic tensile loading. For both interlayer chemistries, the composition profile and microstructure in the joint region confirmed an isothermal solidification mechanism. In addition, the joints were found to be fully dense and contain at most 1.2% intermetallic phases. Tensile testing showed excellent load transfer across the joints with approximately 4% recoverable strain and martensite onset stresses reaching 94% and 89% of the unbonded, annealed NiTi values for Cu-base and Nb-base interlayers, respectively. Lastly, a stable superelastic response was observed under cyclic loading for both bond chemistries, with spatial variation in the strain evolution linked to enhanced stiffness and hardness in the joint region arising from the substitutional Cu and Nb solutes, as confirmed via nanoindentation. This study demonstrates that TLP bonding of NiTi can produce high-strength and nearly intermetallic-free joints without sacrificing functional performance, such as the superelastic response.

cond-mat.mtrl-sci↗

arXiv2024

On-the-Fly Path Planning for the Design of Compositional Gradients in High Dimensions

Functional gradients have recently experienced an explosion in activity due to advances in manufacturing, where compositions can now be spatially varied on-the-fly during fabrication. In addition, modern computational thermodynamics has reached sufficient maturity -- with respect to property databases and the availability of commercial software -- that gradients can be designed with specific sets of properties. Despite these successes, there are practical limitations on the calculation speeds of these thermodynamic tools that make it intractable to model every element in an alloy. As a result, most path planning is carried out via surrogate models on simplified systems (e.g., approximating Inconel 718 as Ni$_{59}$Cr$_{23}$Fe$_{18}$ instead of Ni$_{53}$Cr$_{23}$Fe$_{18}$Nb$_{3}$Mo$_{2}$Ti$_{1}$). In this work, we demonstrate that this limitation can be overcome using a combination of on-the-fly sampling and a conjectured corollary of the lever rule for transformations of isothermal paths in arbitrary compositional dimensions. We quantitatively benchmark the effectiveness of this new method and find that it can be as much as 106 times more efficient than surrogate modeling.

physics.comp-ph↗

arXiv2022

Landmark Enforcement and Style Manipulation for Generative Morphing

Morph images threaten Facial Recognition Systems (FRS) by presenting as multiple individuals, allowing an adversary to swap identities with another subject. Morph generation using generative adversarial networks (GANs) results in high-quality morphs unaffected by the spatial artifacts caused by landmark-based methods, but there is an apparent loss in identity with standard GAN-based morphing methods. In this paper, we propose a novel StyleGAN morph generation technique by introducing a landmark enforcement method to resolve this issue. Considering this method, we aim to enforce the landmarks of the morph image to represent the spatial average of the landmarks of the bona fide faces and subsequently the morph images to inherit the geometric identity of both bona fide faces. Exploration of the latent space of our model is conducted using Principal Component Analysis (PCA) to accentuate the effect of both the bona fide faces on the morphed latent representation and address the identity loss issue with latent domain averaging. Additionally, to improve high frequency reconstruction in the morphs, we study the train-ability of the noise input for the StyleGAN2 model.

cs.CV↗