High-entropy alloys (HEAs) represent a new class of advanced metallic alloys that have gained significant interest. They offer a unique combination of mechanical, thermal, and functional properties, making HEAs ideal for various industrial applications. One such alloy is the recently developed equiatomic body-centred cubic phase AlCoCrFeMo. In particular, thermally sprayed AlCoCrFeMo coatings have gained wide interest due to their exceptional mechanical properties compared to common industrial steel. In the current study, the effect of Mo concentrations on the strength of single crystal AlCoCrFeMo HEA was investigated using molecular dynamics simulation and the phase stability of the alloy was studied using polyhedral template matching. Our results indicate that the local lattice distortion of the alloy is not significantly related to Mo concentration. The yield strength of AlCoCrFeMo HEA obtained through tensile loading, was found to increase with Mo concentration, at a molar ratio of Mo higher than 0.5. Investigation of the deformation behavior of the HEA revealed that bands with high shear strains evolved during plastic deformation. The formation of shear bands after the yield point elucidated the softening exhibited by the material due to localized deformation. These findings provide guidance for tailoring the mechanical properties of AlCoCrFeMo HEA by adjusting Mo concentrations, offering new avenues for designing functional coating materials.

Knowledge of thermal interactions between the substrate and deposited particles during cold spraying can shed light on coating formation and bonding mechanisms. In this study, a mathematical model based on the differential quadrature method was used to solve the hyperbolic heat conduction problem to predict the transient thermal evolution associated with the impact of a single particle. In addition, a 2D finite element model was developed to simulate the thermal and dynamic behavior of particle impact. The two models showed good agreement in predicting the maximum temperature at the particle-substrate interface. It was concluded that the proposed mathematical model could be used to predict the transient temperature of metallic and nonmetallic particle-substrate interfaces during cold spray deposition.

This paper is the second part of a study on how Al and Ta diffusion affects the oxidation of NiCoCrAlYTa coatings. Thermodynamic and diffusion simulations of the coatings with different additions of Al and Ta predicted the development of a typical γ, γ’, ß-phase microstructure and suggested that the ß-NiAl phase was depleted as Al diffused into the substrate. The simulations also indicated that Ta could diffuse back to γ’-Ni 3 (Al,Ta) phase in the substrate with a γ’ depletion due to inward diffusion of Co and Cr from the HVOF-sprayed deposit. How this process impacts microstructure development is discussed in detail.

A low thermal conductivity in feedstock material and high plasma temperatures generally lead to inhomogeneous heating of particles in plasma spraying. Existing modeling methods can determine heat transfer within idealized spherical particles with homogenous morphology, but in many cases, particles have an agglomerated morphology, consisting of multiple smaller particles that are packed together. The reduced contact area between the individual smaller particles results in a drastic reduction of the effective thermal conductivity of the agglomerate. On the other hand, it enhances heat transfer from the plasma gas due to the increased particle surface area and penetration of the hot plasma into the agglomerate. Moreover, the momentum transfer from the plasma to the agglomerate differs from that of a homogenous spherical particle, which can significantly affect heating dynamics. This paper presents a novel particle modeling approach that accounts for all such phenomena. Differences in kinematics and heating dynamics of the agglomerates are analyzed with regard to their packing densities.

In suspension high-velocity oxyfuel (SHVOF) thermal spraying, the suspension is usually injected axially into the combustion chamber. Deposition of oxygen sensitive materials such as graphene can be difficult using this approach as the particles degrade with extended exposure to oxygen at high temperatures. Radial injection outside of the nozzle, however, reduces in-flight particle time thereby accommodating oxygen sensitive nanomaterials. The aim of this study is to investigate how radial injection parameters affect in-flight particle conditions during SHVOF spraying. The models used in this work are shown to accurately predict flame temperature in the combustion chamber for an Al 3 O 2 suspension. Experimental observations of the liquid jet obtained using high-speed imaging are compared to numerically predicted values. The results indicate that in-flight particle characteristics can be improved by more than 30% in SHVOF spraying by optimizing the suspension flow rate and radial injection angle.