Influence of Alumina Nanofibers Sintered by the Spark Plasma Method on Nickel Mechanical Properties

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.

Characteristics of Ternary Metal (Cu-Ni-TiN) Electrodes Used in an Electrical Discharge Machining Process

“…The melting temperatures of the copper and nickel are obtained by a Cu-Ni binary alloy phase diagram of the American Society for Metals (ASM) handbook Volume 3 [1]. The melting temperatures of TiN is obtained as previously shown in a literature [25]. The differences in the Cu ratios of the mixtures of Cu-Ni-TiN electrodes are presented in Table 2.…”

“…At low pressure, chromium particles were better dispersed throughout ten specimens because of the stronger bonding between atoms. In addition, Fonda et al [25] studied the impacts of adding titanium carbide (5-20%) to a copper-tungsten electrode. The results showed that the electrode had the highest density, lowest electric resistivity, highest EDM efficiency, lowest wear rate, and highest material removal rate when 15% titanium carbide was added.…”

“…However, its modification allows one to achieve a significant increase in mechanical properties. Furthermore, the use of TiN electrode can result in an increase in corrosion and wear resistance [24][25][26]. The material removal rate is also an important consideration, as altering the machining gap can increase the material removal rate, as well as improve surface finish [24].…”

Preparation and Study of Composite Materials of the NiAl-Cr-Mo-Nanoparticles (ZrO2, MgAl2O4) System

“…In this work, we investigated the effect of small amounts of ZrO 2 and MgAl 2 O 4 nanoparticles, which have Young’s modulus of 577 GPa [ 32 ] and 275 GPa [ 33 ], respectively, on mechanical properties of the NiAl-CrMo matrix. Thermodynamic modeling was carried out in the Terra ® software environment [ 34 ] to predict the phase formation in the NiAl-Cr-Mo system, as well as with a small amount of carbon that enters the matrix from graphite molds during spark plasma sintering [ 35 , 36 ], considering the formation of a regular Cr-Mo solid solution. A fractographic analysis of the obtained samples was carried out, as well as studies of the features of the temperature dependence of internal friction.…”