Magnetic and structural properties of nanostructured (Fe65Co35)100−xCrx (x = 0, 10) powders prepared by mechanical alloying process

• Adding 10% Cr to Fe65Co35 composition has increased the required milling time to accomplish the formation of solid solutions.
• Also, this addition has negligible effect on the grain size evolution during milling operations.
• However, its addition leads to a substantial decrement of Ms and a remarkable increment of Hc of the alloy.

This work focuses on the preparation of nanostructured (Fe65Co35)100−xCrx (x = 0, 10) powders by mechanical alloying. The powders are milled for different milling times (up to 90 h). Characterizations of the milled powders were carried out by X-ray diffraction (XRD), scanning electron microscopy (SEM) and vibratory sample magnetometer (VSM). It was observed that the formation of bcc-FeCo and bcc-FeCoCr phases were completely accomplished after 60 and 90 h of milling, respectively. The grain size decreases and the microstrain increases with increasing the milling time. In the initial stages of milling (up to 15 h) for the (Fe65Co35)90Cr10 powders, the saturation magnetization (Ms) decreased but further milling (up to 90 h) increased the Ms. However, the trend for coercivity was different and three stages were observed. An initial increasing stage (up to 15 h of milling), followed by a reducing middle stage (up to 60 h of milling) and then again an increasing final stage (up to 90 h milling). Besides, for the same milling time of 90 h, the addition of 10 at.% of Cr to Fe65Co35 powders leads to higher coercivity and lower saturation magnetization.

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