Al-Permalloy (Ni71.25Fe23.75Al5) obtained by mechanical alloying. The influence of the processing parameters on structural, microstructural, thermal, and magnetic characteristics

Abstract

A new alloy, permalloy alloyed with aluminum, has been obtained by mechanical alloying using elemental powders as raw materials. The new alloy was obtained in powder form by adding an amount of 5 wt% of Al to permalloy (75% Ni and 25% Fe, wt.%) resulting Al-Permalloy with Ni71.25Fe23.75Al5 composition. The alloy was obtained using different ball to powder ratio (BPR): 4:1, 8:1 and 17:1 and keeping the rest of the mechanical alloying/milling parameter constant. The BPR influences the time required for the alloy synthesis and alloy characteristics. The time required for alloy synthesis as FCC single phase varies from 4 h when using a BPR of 17:1 to 8 h when using a BPR of 4:1. A more compact cubic structure is obtained when using a BPR of 8:1. The particles are flattened for all BPRs used, but upon changing the BPRs particles shape is changing and become more or less flattened. Large particles have been obtained when using BPRs of 4:1 and 17:1 and finer particles when using a BPR of 8:1. Curie temperature of the Al-Permalloy is depending on synthesis conditions varying from 478 °C to 501 °C. The higher saturation magnetization has been found when using a BPR of 8:1. The powder characteristics evolution upon increasing the milling time for all three BPRs is discussed in the light of X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectrometry, differential scanning calorimetry, particles size analyses and magnetic investigation.