The Effect of Heat Treatment on the Microstructure and Mechanical Properties of 2D Nanostructured Au/NiFe System

Abstract

Nanostructured NiFe film was obtained on silicon with a thin gold sublayer via pulsed electrodeposition and annealed at a temperature from 100 to 400 °C in order to study the effect of heat treatment on the surface microstructure and mechanical properties. High-resolution atomic force microscopy made it possible to trace stepwise evolving microstructure under the influence of heat treatment. It was found that NiFe film grains undergo coalescence twice—at ~100 and ~300 °C—in the process of a gradual increase in grain size. The mechanical properties of the Au/NiFe nanostructured system have been investigated by nanoindentation at two various indentation depths, 10 and 50 nm. The results showed the opposite effect of heat treatment on the mechanical properties in the near-surface layer and in the material volume. Surface homogenization in combination with oxidation activation leads to abnormal strengthening and hardening-up of the near-surface layer. At the same time, a nonlinear decrease in hardness and Young’s modulus with increasing temperature of heat treatment characterizes the internal volume of nanostructured NiFe. An explanation of this phenomenon was found in the complex effect of changing the ratio of grain volume/grain boundaries and increasing the concentration of thermally activated diffuse gold atoms from the sublayer to the NiFe film.

Method of surface energy investigation by lateral AFM: application to control growth mechanism of nanostructured NiFe films

“…The chemical composition of the films was valuated by energy-dispersive X-ray microanalysis using a Bruker XFlash MIN SVE microanalyzer, working in conjunction with a Hitachi TM3030 SEM. The values of the normal specific surface energy (SSE) were determined with a widely known AFM technique called force spectroscopy 69 , 70 . The lateral SSE was studied using a unique technique based on recording the angle of the cantilever twist when scanning in contact with the surface, which was developed as part of this work (see paragraph 3.1).…”

Efficiency of Magnetostatic Protection Using Nanostructured Permalloy Shielding Coatings Depending on Their Microstructure

“…The unit cell parameter (a) and cell volume (V) decrease nonlinearly from 3.578 to 3.567 Å and from 45.80 to 45.38 Å 3 with transition from stationary to pulsed electrodeposition and with the pulse duration decreasing. The reason for the compression of the crystal lattice can be two factors: (1) surface compression of grains with a decrease in their size [ 27 , 49 , 50 ], and (2) the effect of the chemical composition (a decrease in the Fe content with an atomic radius bigger (r Fe = 0.156 nm) than that of Ni (r Ni = 0.124 nm)).…”

“…The most commonly used material for creating magnetostatic and electromagnetic shields is soft magnetic alloy of Ni and Fe or permalloy. Ni-rich permalloy has high permeability, low coercivity, and small magnetic anisotropy [ 11 , 17 , 19 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 ]. Electrodeposited coatings are promising due to the high economic viability of the electrodeposition process [ 29 , 30 , 31 , 32 ].…”

Effect of Titanium and Boron Microalloying on Sulfide Stress Cracking in C110 Casing Steel

“…All specimens were air cooled to room temperature after tempering. After polishing, quenched samples were eroded in 60 °C saturated picric acid, and the PAGS was measured by optical microscopy Axio Imager A2m (Zeiss, Jena, Germany) using the following equation [ 14 ]: where d is the diameter of prior austenite grains, S is the total area of all grains in the analyzed optical microscopy images, and n is the number of the prior austenite grains.…”