Structural and compositional stability of the mechanically alloyed (Fe, Mo)-Al at elevated temperatures
Abstrakt
Fe, Al, and Mo elemental powder mixture with composition Fe-29 at.% Al-1.5 at.% Mo was alloyed via solid-state reactions in a planetary ball mill. The composition, structural parameters, and magnetic properties of the powdered samples after milling were studied at room temperature by scanning electron microscopy, X-ray diffraction and magnetic measurements.
Subsequently, the samples were exposed to temperatures up to 1000 degrees C directly in a heating chamber of diffractometer and/or magnetometer and the evolution of the structural/compositional and magnetic changes in relation to their metastable asalloyed states were followed. The powdered sample milled 32 h, sample denoted as S/32, has yielded the finest structure of homogeneously distributed elements and quasi-binary bcc-(Fe,Mo)-Al composition well-established by the elemental maps measured by an energy-dispersive X-ray spectroscopy.
This sample was stable also during a treatment at elevated temperatures as both in-situ X-ray diffraction and thermomagnetic measurements have evidenced. On the other hand, the next 32 h of milling (in sum 64 h; sample S/64) has led to a partial decomposition and the small Al and Mo peaks reappeared in diffraction patterns.
The behavior of this sample at elevated temperatures is compared with the previous one and moreover, with the sample after 16 h of milling (S/16) which has yielded similarly the Al and Mo diffraction peaks. Despite the structural! compositional states of the 5/16 and S/64 samples seem to be during thermal treatment similar, their magnetic behavior is different and none of them achieves the properties of S/32 sample.