Abstract
The study investigated the dependence of the indentation load on nanomechanical properties for a gas-borided layer produced on Inconel 600-alloy. During the measurements, the indentation load range from 10 mN to 500 mN was used. Three types of tested areas, differing in the concentration of chromium, were examined. The increase in chromium concentration was accompanied by an increase in indentation hardness and Young’s modulus. Simultaneously, the increase in the indentation load resulted in a decrease in the indentation hardness and Young’s modulus, for each type of the tested area. The presence of the indentation size effect was analyzed using four models: Meyer’s law, Hays and Kendall model, Li and Bradt model, Nix and Gao model. For all tested areas, good agreement with the Meyer’s law was obtained. However, areas with a higher chromium concentration were more susceptible to indentation size effect (ISE). The proportional specimen resistance (PSR) model was used to describe the plastic-elastic behavior of the tested materials, as well as to detect the presence of ISE. It was found that the increase in chromium concentration in the tested area was accompanied by a greater tendency to elastic deformation during nanoindentation.
Highlights
Nanomechanical PropertiesBoriding of nickel-based alloys causes the formation of a multiphase layer which differs in phase composition depending on the chemical composition of the substrate material
Zones marked as (1) and (2) can be collectively referred to as the diffusion layer. Such a layer is a result of diffusion of boron atoms into the workpiece, creating new phases that differ in structure and properties compared to the substrate material (3)
The good quality of the produced layer can be considered in terms of the presence of small amount of porosity, which was observed near the top surface
Summary
Boriding of nickel-based alloys causes the formation of a multiphase layer which differs in phase composition depending on the chemical composition of the substrate material. In the case of the boride layer containing both nickel and chromium borides, the hardness ranged from 19.95 to 36.26 GPa. A similar effect was obtained for the Young’s modulus [2]. The appropriate technique used to determine the hardness and Young’s modulus of a fine-grained microstructure consisting of various types of borides is nanoindentation. This method of measurements allows for a detailed analysis of the mechanical properties in the nanoscale for various types of borides. Fine-grained cermets showed a more pronounced tendency towards ISE [11] Such conclusions inspired the analysis of the tendency to the indentation size effect in multiphase borided layers
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