arXiv subjects

Nensi Toncich

Publications and source records attributed to Nensi Toncich.

3 recordsLinked to original sources

arXiv2026

Ru Alloying in Ni/Al Reactive Multilayers: Experimental Observations and Molecular Dynamics Simulations

Reactive multilayer thin films, a class of energetic materials, are increasingly recognized for their potential in joining applications, utilizing the chemical energy released as heat during exothermic reactions. These materials hold also promise for additional diverse technological applications, which require precise control over heat release rates and reaction propagation velocities. The microstructural properties of reactive multilayers play a critical role in determining their chemical reaction behavior. Among these, Ni/Al reactive multilayers have been extensively studied and used due to their favorable characteristics. In this study, we explore the incorporation of ruthenium (Ru) as a co-alloying element with nickel (Ni) in the Ni/Al system to investigate its impact on the materials properties, with a particular focus on reaction velocity and temperature. Ru enhances the reaction rates, but also causes a composition dependent phase transition in the as-deposited state from fcc to hcp. Additionally, molecular dynamics simulations are employed to examine the effects of Ru co-alloying with Ni, providing deeper insights into the underlying mechanisms. This work aims to advance the understanding of Ru's role in influencing the performance of Al/Ni-based reactive multilayers for advanced applications.

cond-mat.mtrl-sci↗

arXiv2025

Composition Effects on Ni/Al Reactive Multilayers: A Comprehensive Study of Mechanical Properties, Reaction Dynamics and Phase Evolution

Ni/Al reactive multilayers are promising materials for applications requiring controlled local energy release and superior mechanical performance. This study systematically investigates the impact of compositional variations, ranging from 30 to 70 at.% Ni, and bilayer thicknesses (30 nm and 50 nm) on the mechanical properties and reaction dynamics of Ni/Al multilayers. Multilayers with varying Ni-to-Al ratios were fabricated and subjected to instrumented nanoindentation testing to evaluate hardness and elastic modulus. Combustion experiments, conducted on dogbone-shaped multilayers deposited onto silicon wafers with thermal barrier coatings, characterized the reaction front's speed, temperature, and the resulting phases. The findings revealed that composition variations within this range enable precise tuning of reaction speed and temperature without significant changes in mechanical properties, while deviations in modulus and hardness at higher nickel concentrations suggest microstructural influences. Notably, phase formation in Al-rich samples deviated from equilibrium predictions, highlighting the role of kinetic factors, such as diffusion and rapid quenching, in driving non-adiabatic processes during phase evolution. Molecular dynamics simulations provided complementary atomistic insights into mechanical responses and reaction kinetics, bridging experimental observations with theoretical predictions. This integrated approach advances the understanding of Ni/Al multilayers, offering a framework for optimizing their composition and structural design to achieve tailored performance for application-specific requirements.

cond-mat.mtrl-sci↗

arXiv2024

Physical Properties and Thermal Stability of Zirconium Platinum Nitride Thin Films

Ternary transition metal nitrides (TMNs) promise to significantly expand the material design space by opening new functionality and enhancing existing properties. However, most systems have only been investigated computationally and limited understanding of their stabilizing mechanisms restricts translation to experimental synthesis. To better elucidate key factors in designing ternary TMNs, we experimentally fabricate and analyze the physical properties of the ternary Zr-Pt-N system. Structural analysis and DFT modeling demonstrate that Pt substitutes nitrogen on the non-metallic sublattice, which destabilizes the rock-salt structure and forms a complex cubic phase. We also show insolubility of Pt in the Zr-Pt-N at 45 at % with the formation of a secondary Pt-rich phase. The measured reduced plasma frequency, decrease in resistivity, and decrease in hardness reflect a dominance of metallic behavior in bonding. Contrary to previous computational predictions, Zr-Pt-N films are shown to be metastable systems where even low Pt concentrations (1%) facilitate a solid reaction with the Si-substrate, that is inaccessible in ZrN films.

cond-mat.mtrl-sci↗