Magnetic Behavior of Dilute Fe‐Doped Martensitic Cu–Al Alloys: Magnetization and EPR Study

The magnetic properties of nanocrystalline Cu–Al–Fe alloys with a dilute Fe concentration of 0.1–1.0 wt% were investigated. PXRD shows that the alloys are dominated by the β1ʹ martensitic phase, while the lattice microstrain slightly increases with increasing Fe content. The 0.1 wt% Fe alloy exhibits weak, nearly reversible magnetization characteristic of a magnetically soft system. Increasing the Fe concentration to 1.0 wt% leads to higher magnetization, finite coercivity and remanence, along with the appearance of ZFC‐FC irreversibility with a blocking‐like maximum near 7 K. X‐band EPR spectra reveal contributions from both isolated Fe ³⁺ ions and exchange‐coupled Fe‐related magnetic centers. The low‐field microwave absorption signal observed in the 0.1 wt% Fe alloy disappears as the Fe concentration increases. An anomaly in EPR parameters for Fe‐related paramagnetic centers near 25 K indicates changes in spin dynamics associated with Fe–Fe interactions. The magnetic behavior is attributed to Fe atoms incorporated into the martensitic lattice.