Microstructure and mechanical properties of rapidly solidified FeAlCr intermetallic compound

Abstract

In this work results regarding microstructural characterization of a melt‐spun intermetallic compound Fe40Al5Cr (% at.) produced by rapid solidification employing the melt spinning technique at three different tangential wheel speeds (12, 16 and 20 ms‐1) are presented. Melt spun ribbons were characterized by optical and scanning electron microscopy (SEM) in order to observe morphology, grain size, ribbon thickness and also fracture surfaces after tensile tests. EDS coupled to SEM was employed to perform punctual and scan line chemical analyses on samples, x‐ray diffraction (XRD) was utilized to identify crystal structure and phases. Transmission electron microscopy (TEM) was employed to confirm crystal structure and also to characterize nanopores formed in the specimens by vacancy clustering. With regard to mechanical properties, micro hardness Vickers measurements as well as tensile tests at room temperature were applied to the rapidly solidified ribbons.The grain size of rapidly solidified Fe40Al5Cr ribbons suffered a drastic reduction as compared with alloys of the same composition produced by conventional melting and casting methods, and in melt‐spun ribbons it decreases as the wheel speed increases. Punctual and line‐scanning chemical analyses revealed that Cr enters in solid solution in FeAl matrix. Hardness measurements revealed a softening in rapidly solidified FeAlCr ribbons as compared with FeAl alloys and tensile test exhibited a (transgranular + intergranular) mode of fracture, reaching up to 3 % of elongation in FeAlCr alloys. The presence of porous (meso and nano) were also characterized.