Slawomir M. Kaczmarek; Tomasz Bodziony; Vinh H. Tran; Pawal Figiel; Anna Biedunkiewicz; Grzegorz Leniec
Abstract
Series of nanocrystalline and TiC, TiB2, and B4C powders as dopants (3%-20%) embedded in an AISI 316L austenitic steel have been prepared and investigated by ferromagnetic resonance and magnetic measurements. The homogeneous composites with the dopants up to x = 7 vol. % exhibit superparamagnetic properties, ...
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Series of nanocrystalline and TiC, TiB2, and B4C powders as dopants (3%-20%) embedded in an AISI 316L austenitic steel have been prepared and investigated by ferromagnetic resonance and magnetic measurements. The homogeneous composites with the dopants up to x = 7 vol. % exhibit superparamagnetic properties, characterized by bifurcation between the field-cooled MFC(T) and zero-field cooled MZFC(T) magnetization below Tir and a maximum at Tmax in low-field MZFC(T) curves. We found that the Tir and Tmax values depend proportionally on the dopant concentrations x. The magnetization measurements in fields above 1000 Oe suggested an induced phase transition from superparamagnetic state to ferromagnetic one but presumably without long-range magnetic correlation. An analysis of magnetic anisotropic energy barrier distributions implied that different sizes and compositional types of dopants may contribute to the superparamagnetic relaxation process. The results demonstrate the possibility of obtaining new steel-based materials with desired properties and potential applications as combining magnetic and mechanical advantages.
N. A. Al-Mobarak
Abstract
The corrosion resistance of titanium alloy, Ti–6Al–7Nb, was investigated through electrochemical impedance spectroscopy (EIS), open circuit potential (OCP) measurements and scanning electron microscopy (SEM) and Energy Dispersive X-ray (EDX) analysis. The tests were done in Hank's solution ...
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The corrosion resistance of titanium alloy, Ti–6Al–7Nb, was investigated through electrochemical impedance spectroscopy (EIS), open circuit potential (OCP) measurements and scanning electron microscopy (SEM) and Energy Dispersive X-ray (EDX) analysis. The tests were done in Hank's solution at 37 o C for immersion periods expanded to 169 h. A high corrosion resistance was obtained for Ti–6Al–7Nb alloy in hank's solution due to the stable passive film formed on its surface. The EIS results indicated the presence of a single passive layer immediately after immersion. However, after 24 h of immersion in hank's solution, the EIS exhibited the presence of a bi-layered surface corresponding to an inner layer and an outer layer. Further, the film formed on the alloy after 169 h was confirmed by SEM and EDX analysis as calcium and phosphate may be due to apatite formation.
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