Abstract:
The properties of alloys (Fe$_{0.95-y}$Cr$_{0.05}$Niy)$_{83}$C$_{17}$ è (Fe$_{0.90-y}$Cr$_{0.10}$Ni$_y$)$_{83}$C$_{17}$, where $y$ = 0.05 and 0.10, obtained by mechanosynthesis and subsequent annealing, were studied by Mossbauer spectroscopy and magnetic measurements, using X-ray diffraction data. As a result of annealing at 500$^\circ$C, nanocomposites are formed with a similar phase composition (cementite and austenite matrix with the ferrite inclusions) and maximum values of the coercive force $H_{\mathrm{c}}$. At the same time, $H_{\mathrm{c}}$ of high-chromium composites is more than two times higher than $H_{\mathrm{c}}$ of low-chromium composites (210–250 and 100 A/cm, respectively). Mossbauer studies have shown that the cementite of high-chromium alloys is in a paramagnetic state, while that of low-chromium alloys is in a ferromagnetic state. This aspect determines the features of magnetization reversal of close to the critical single-domain size ferrite inclusions, which leads to different maximum values of $H_{\mathrm{c}}$ for low- and high-chromium nanocomposites.
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