In this work, the effect of the addition of Zirconium on the microstructure, hardness, wear behavior and magnetic properties of NiCoCrFe High Entropy Alloy (HEA) was investigated. The crystal structures and phase evolution of the alloys were characterized using X-Ray Diffraction (XRD). XRD patterns showed the FCC and BCC solid solutions in both alloy powders. To investigate the effect of Zr element on the wear behavior of NiCoCrFe HEA, the alloys, in the form of powder, were compressed using Spark Plasma Sintering (SPS) process, and then, the pin on disk wear test was applied. The results showed that after SPS, BCC/FCC phases of the NiCoCrFeZrx (x = 0) alloy had converted to single-phase FCC (NiCoCrFeZr0.4); however, the mechanical properties and wear behavior of the alloy improved compared to the NiCoCrFe alloy. The micro-hardness and nano-hardness of NiCoCrFe alloy increased from 682 ± 7 and 672 ± 7 Vickers to 828 ± 10 and 845 ± 10 Vickers, respectively. Moreover, the addition of Zr led to significant increasing in wear resistance and decreasing the coefficient of friction. Results of the scanning electron microscope (SEM) equipped with an XRD energy spectrometer (EDS) illustrated that the presence of Zr led to the conversion of the dominant abrasive mechanism to adhesive mechanism. Eventually, the results of the Vibrating Sample Magnetometer (VSM) indicated that the addition of Zr element led to the tendency of NiCoCrFe alloy to be paramagnetic. In this way, the magnetic saturation is reduced by 15%, and the coercive force is increased by 133%.

Investigation of hardness, wear and magnetic properties of NiCoCrFeZrx HEA prepared through mechanical alloying and spark plasma sintering

Cavaliere P.
2021-01-01

Abstract

In this work, the effect of the addition of Zirconium on the microstructure, hardness, wear behavior and magnetic properties of NiCoCrFe High Entropy Alloy (HEA) was investigated. The crystal structures and phase evolution of the alloys were characterized using X-Ray Diffraction (XRD). XRD patterns showed the FCC and BCC solid solutions in both alloy powders. To investigate the effect of Zr element on the wear behavior of NiCoCrFe HEA, the alloys, in the form of powder, were compressed using Spark Plasma Sintering (SPS) process, and then, the pin on disk wear test was applied. The results showed that after SPS, BCC/FCC phases of the NiCoCrFeZrx (x = 0) alloy had converted to single-phase FCC (NiCoCrFeZr0.4); however, the mechanical properties and wear behavior of the alloy improved compared to the NiCoCrFe alloy. The micro-hardness and nano-hardness of NiCoCrFe alloy increased from 682 ± 7 and 672 ± 7 Vickers to 828 ± 10 and 845 ± 10 Vickers, respectively. Moreover, the addition of Zr led to significant increasing in wear resistance and decreasing the coefficient of friction. Results of the scanning electron microscope (SEM) equipped with an XRD energy spectrometer (EDS) illustrated that the presence of Zr led to the conversion of the dominant abrasive mechanism to adhesive mechanism. Eventually, the results of the Vibrating Sample Magnetometer (VSM) indicated that the addition of Zr element led to the tendency of NiCoCrFe alloy to be paramagnetic. In this way, the magnetic saturation is reduced by 15%, and the coercive force is increased by 133%.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11587/457293
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