Phase Transformation in the L1 2 -Structure of Fe 3 Ge Driven by Mechanical Milling

We report for the first time a phase transformation from the f.c.c.-like L1 2 structure to the b.c.c. structure induced by mechanical milling. This is found in Fe 3 Ge. X-ray diffraction shows that after short periods of milling, anti-site disorder is created in L1 2 -Fe 3 Ge indicated by the disappearance of superlattice reflections and that after long periods of milling, a nanocrystalline b.c.c. solid solution of Ge in Fe is obtained. High-field magnetization at 4.2 K increases upon disordering in f.c.c. L1 2 and decreases upon phase transformation from f.c.c. to b.c.c. Thermal analysis of various Fe 3 Ge samples gives more insight in the change of magnetic behaviour and the phase transformation during milling.