Structure of Complex Concentrated Alloys Derived from Iron Aluminide Fe3Al

The phase structure and composition of a series of four alloys based on Fe3Al was investigated by means of scanning electron microscopy, X-ray diffraction and transmission electron microscopy. The materials were composed of Fe and Al with a fixed ratio of 3:1 alloyed with V, Cr and Ni at 8, 12, 15 and 20 at. % each (composition formula: Fe3(100-3x)/4 Al(100-3x)/4VxCrxNix). For 8% alloying, the material is single-phase D0(3). Furthermore, 12 and 15% alloying results in bcc-B2 phase separation on two length scales. Moreover, 20% alloying gives rise to the FeNiCrV & sigma; phase supplemented by B2. These findings are discussed with respect to the results obtained via Calphad modeling using the TCHEA5 database and can serve in further improvement.