This study improves upon understanding of the effects of reinforcing particle content and microstructure on the mechanical properties and failure of low-pressure cold spray fabricated tungsten carbide-nickel (WC-Ni) metal matrix composite (MMC) coatings. Image analyses were performed on scanning electron microscope (SEM) micrographs of the coatings to characterize the microstructure and measure the total interfacial area between the reinforcing WC particles and the Ni metal matrix, the mean free path between the particles, the average particle size, and the porosity of the coating. Uni-axial quasi-static tensile testing was conducted on the as-sprayed coatings. The tensile stresses that were measured were coupled with the evolving strains that were calculated by using the digital image correlation (DIC) technique. The results showed that mechanical properties, namely tensile strength and Young's modulus, of the composite coatings increased with increasing WC content in the coatings. The increases were due to the refined microstructural features that occurred with the decrease in the porosity of the coating that was caused by significant consolidation of the Ni metal matrix. Furthermore, this increase in strength and Young's modulus was also related to the increase in the interfacial area between the reinforcing carbide particles and the metal matrix that was caused by the increase in carbide content in the coating, a decrease in the average size of the carbides in the coating, and a reduction of the mean free path between the carbide particles. A framework was presented to elicit the micro-macro relationships between the microstructure and the tensile strength of the cold-sprayed composite coatings. Based on the developed framework, two distinct coating mechanical strength regimes were observed, indicating a significant increase in the tensile strength of the coatings that were comprised of more than 30 wt% WC due to the refined microstructure of the coatings. The higher value tensile strength regime was also confirmed by the larger average mechanical energy absorbed to failure under tensile loading and lower damage accumulation. This collection of data of mechanical properties and the microstructures presented in this study are important to validate numerical-based failure models for cold-sprayed composite coatings. Altogether, the results of this study will enhance understanding of the sensitivity of mechanical response of a composite coating to microstructural changes.

On the microstructure-dependency of mechanical properties and failure of low-pressure cold-sprayed tungsten carbide-nickel metal matrix composite coatings

Laser-aided additive manufacturing of high entropy alloys: Processes, properties, and emerging applications

TiAl-5wt.%Ti2AlC-3wt.%Mn composites reinforced by the addition of Mn and in situ synthesized Ti2AlC nanoparticles with a novel microstructure were fabricated. The microstructure and compressive properties of the fabricated composites were thoroughly investigated. The interface between the nanoparticles and the TiAl matrix maintained a very small mismatch and exhibited a stable combination, leading to noticeable grain refinement in the fabricated composites. Furthermore, the yield strength, maximum compressive strength, fracture strain, and strength-ductility balance of the TiAl-5wt.%Ti2AlC-3wt.%Mn composites increased by 30.7%, 10.1%, 5.5%, and 9.9%, respectively, compared with those of the TiAl alloy. The mechanisms by which the properties of the composites were improved mainly thermal mismatch strengthening, Orowan strengthening, grain refinement strengthening, and solid solution strengthening.

Microstructural configuration and compressive deformation behavior of a TiAl composite reinforced by Mn and in situ Ti2AlC particles

Achieving higher dynamic mechanical response by adjusting texture through twinning in a ZK61 Mg alloy

Fabrication of nano-TiC reinforced high Nb-TiAl nanocomposites by electron beam melting

Mechanical and microstructural properties of a CoCrFe0.75NiMo0.3Nb0.125 high-entropy alloy additively manufactured via cold-spray

On the evaluation of mechanical properties and ballistic performance of two variants of boron carbide

In this paper, a microstructure-based finite element model for nano-grained ( γ + α 2 ) -TiAl/Al2O3 cermets is proposed based on a modified variational formulation of the Gurson model for an elastic-plastic porous material. In the modeling approach, the high volume fraction of alumina, variability in material characteristics, and microstructural features (e.g., inclusion size) are considered. Mechanical properties and microstructure inputs are derived from nanoindentation and microscopy analysis performed for this study, as well as using available information in the literature. Once developed, modeling results are validated against experimental quasi-static compressive stress-strain measurements using digital image correlation techniques. The validation is extended by comparing experimental observations and computational outputs of the ratio of the lateral to axial strain (as a measure of deformation), and reasonable agreement is found. Once the model is validated for an experimentally known condition, the effect of varying the mechanical properties (e.g., strain hardening parameters and elastic modulus) and microstructure variables (e.g., alumina volume fraction and porosity) on material responses are then explored. These results serve as a foundation for future microstructure optimization.

Haoyang Li

Papers

Mechanical and microstructural properties of a CoCrFe0.75NiMo0.3Nb0.125 high-entropy alloy additively manufactured via cold-spray

On the evaluation of mechanical properties and ballistic performance of two variants of boron carbide

An experimental and numerical study of novel nano-grained (γ+α2)-TiAl/Al2O3 cermets

Two-dimensional dynamic damage accumulation in engineered brittle materials

Micro-hardness and strain-rate-dependent compressive response of an ultra-light-weight Mg-Li-Al alloy