Monitoring the alloying process of mechanically synthesized Fe80Ni20 through changes in magnetic properties

Highlights: • Changes in magnetic properties during mechanical alloying of Fe₈₀Ni₂₀ are reported. • Mechanical synthesis can be divided into three distinct stages. • Measuring magnetic properties can lead to better control over the alloying process. Fe₈₀Ni₂₀ was prepared by mechanical synthesis using a Fritsch Pulverisette Premium (P7) planetary ball mill at 400 RPM. The alloying process was monitored by measuring the magnetic properties of 14 subsamples taken at different milling times (1–2160 min) as well as structural modifications using powder X-ray diffraction and high-resolution imaging. A macroscopically homogeneous body-centered cubic (bcc) alloy with crystallite sizes below 11 nm and microstrain above 1.2% was reached after 960 min (16 h) of milling. The magnetic properties show three distinct stages: (1) the size reduction of the elementary powders, (2) alloying and (3) reduction in particle size of the final alloy.