In-situ mechanical investigation of the deformation of splat interfaces in cold-sprayed aluminum alloy

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

卷:737

Article

Nautiyal, Pranjal¹  Zhang, Cheng¹  Champagne, Victor K.²  Boesl, Benjamin¹  Agarwal, Arvind¹ 

[1] Florida Int Univ, Plasma Forming Lab, 10555 West Flagler St, Miami, FL 33174 USA

[2] US Army Res Lab, Weap & Mat Res Directorate, Aberdeen, MD 20783 USA

关键词: Cold spray;    Mechanical properties;    Splat sliding;    Multiscale mechanics;    In-situ investigation;   

DOI  :  10.1016/j.msea.2018.09.065

来源: Elsevier

【 摘 要 】

The mechanical properties of cold sprayed deposits, with splats as their building blocks, are affected by debonding and relative sliding of splats during mechanical loading. In this study, inter-splat deformation behavior in 6061 Al coatings is investigated by in-situ mechanical characterization for real-time visualization. The role of processing gas type (He vs. Air), splat geometry, particle bonding, and post-spray heat treatment on splat sliding is evaluated. High porosity and poor splat-bonding in air-sprayed coating result in inferior microhardness (917 MPa) and flexural strength (120 MPa), as compared to He-sprayed coating which exhibits microhardness and flexural strength of 1000 MPa and 450 MPa, respectively. In-situ cyclic bending of coatings is performed inside a scanning electron microscope to examine the splat deformation behavior. Digital image correlation (DIC) analysis of the real-time videos is performed to determine local microstructure strains, experimentally demonstrating splat sliding phenomenon for the first time. Heat-treatment of the coatings heals inter-splat microcracks, reduces porosity and consequently improves the mechanical properties. DIC strain maps revealed arrested splat sliding after heat-treatment. A splat sliding factor (SSf) is introduced, which compares coldsprayed microstructure deformation with the bulk structure like substrate, providing quantitative information about inter-splat bonding. The SSf is found to be higher for air-sprayed coating (similar to 1.4) as compared to Hesprayed coating (similar to 0.28), and is further reduced after heat-treatment. The correlation between splat sliding and microstructure will enable development of coatings with predictable and improved mechanical properties by cold spray.

【 授权许可】

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