Atom Location by Channeling-Enhanced Microanalysis (ALCHEMI) Study of Structure of Complex Concentrated Alloys Derived From FeAl Iron Aluminide
Abstrakt
Two sets of alloys derived from FeAl iron aluminide, with the ratio of Fe and Al equal 55:45 and 50:50, respectively, were investigated. The FeAl alloys were modified by the addition of chromium and vanadium in symmetric concentrations of 5 to 25 atomic percent.
The structure was investigated by X-ray diffraction and transmission electron microscopy, and the high-temperature yield stress was determined by compression tests. The B2 order of the FeAl iron aluminide is retained in the quasiternary alloy Fe(100-x)/2Al(100-x)/2Vx/2Crx/2 even for x = 30 or 40 (index and x are atomic percent).
The site occupancy was determined by atom location by channeling-enhanced microanalysis (ALCHEMI): The development of the occupation of V atoms in Al sublattice, and similarly for Cr in Fe sublattice, has been investigated. This distinction weakens with the increasing alloying.
This results in equal occupancy of both lattice sites in the equiatomic complex concentrated alloy (CCA) FeAlCrV. In the alloys with x = 30, 40, and 50, also the nanoprecipates of D03 structure were detected.
A pronounced increase of the yield stress with the increasing content of both Cr + V up to the value of Cr + V = 30 at. pct was observed. The alloys with the asymmetric concentration of Fe:Al = 55:45 exhibited a higher yield stress.