Formation and decomposition of laser-deposited metastable Fe-Cr phases

Abstract

Contrary to expectations to obtain a continuous series of supersaturated b.c.c. Fe-Cr solid solutions by co-deposition of both metals in cross-beam PLD, there form unusual for this materials system metastable intermetallic phases. The structure of alloys develops from a tetragonally distorted b.c.c. at low Cr-content through a face centered orthorhombic (f.c.o.) to partly ordered primitive orthorhombic (p.o.) crystal structure of the A15-like type at nearly equiatomic composition. It seems to be the first observation of an ordering of restrictedly soluble components under the bombardment of hyperthermal species in PLD. Intriguing fact is that these metastable phases are initially paramagnetic (PM) at room temperature but become ferromagnetic (FM) after annealing in a temperature range 400-500 °C or under ion bombardment. The induced PM-FM transformation in the alloys is demonstrated to be useful for formation of stable lateral magnetic microstructures.