Abstract
The article presents the study of alumina nanoparticles’ (nanofibers) concentration effect on the strength properties of pure nickel. The samples were obtained by spark plasma sintering of previously mechanically activated metal powders. The dependence of the grain size and the relative density of compacts on the number of nanofibers was investigated. It was found that with an increase in the concentration of nanofibers, the average size of the matrix particles decreased. The effects of the nanoparticle concentration (0.01–0.1 wt.%) on the elastic modulus and tensile strength were determined for materials at 25 °C, 400 °C, and 750 °C. It was shown that with an increase in the concentration of nanofibers, a 10–40% increase in the elastic modulus and ultimate tensile strength occurred. A comparison of the mechanical properties of nickel in a wide range of temperatures, obtained in this work with materials made by various technologies, is carried out. A description of nanofibers’ mechanisms of influence on the structure and mechanical properties of nickel is given. The possible impact of impurity phases on the properties of nickel is estimated. The tendency of changes in the mechanical properties of nickel, depending on the concentration of nanofibers, is shown.
Highlights
Nickel-based materials are used in various industries: aviation, astronautics, engineering, energy, and others [1]
This is illustrated by the fact4that of 16powders with a size of 20 μm or more were ground to 10 μm or less
Nickel samples containing alumina nanofibers in the range of 0–0.1 wt.% were obtained by mechanical activation of powders with the subsequent addition of nanoparticles under the influence of ultrasound during mixing and spark plasma sintering
Summary
Nickel-based materials are used in various industries: aviation, astronautics, engineering, energy, and others [1]. Nickel is a universal chemically stable metal. Pure nickel is not used as a structural material because of its high density and relatively low strength. Dispersion strengthening of metals is caused by both coherent and incoherent particles and precipitates. There are many works related to the strengthening of molybdenum [4] and aluminum [5,6,7] by 0.01–0.1 wt.% spherical nanoparticles of refractory oxides. It was shown that the increase in tensile strength could reach 30–300% compared to pure metal. Materials were obtained using powder metallurgy technologies. The addition of nanoparticles into a powder matrix leads to various strengthening effects:
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