It has been known for over forty years that B2-structured FeAl can undergo a paramagnetic to ferromagnetic transition upon cold working. Strain-induced ferromagnetism (SIF) in FeAl arises from the generation of APB tubes, where Fe atoms can have ≥3 like nearest neighbors. The resulting saturation magnetization, Ms, depends on both the Fe:Al ratio, the presence of substitional alloying elements and the degree of deformation. This presentation will outline a semi-quantitative model that describes SIF in terms of the local environment theory applied to the atoms in APB tubes. The effects of plastic strain on the magnetic properties of other strongly-ordered intermetallics will also be briefly outlined. Finally, we will briefly discuss the role of APB tubes on the work-hardening of intermetallic compounds. This research is supported by the US Department of Energy, Office of Basic Energy Sciences grant DE- SC0018962.

PART 2 : High entropy FeNiMnAlCr alloys.

Two types of high-entropy FeNiMnAlCr stainless steels have been developed, one of which is single-phase f.c.c. in the as-cast state while the other consists of alternating f.c.c and B2-ordered lamellae, formed via a eutectic transformation, with a Kurdjumov-Sachs orientation relationship between the phases. Both high entropy alloys (HEAs) show good strength and ductility at temperatures from room temperature up to 973 K, and show superior strength to 316 stainless steel at all temperatures. Further, both HEAs show good oxidation resistance and superior aqueous corrosion resistance compared to 316 stainless steel. The deformation mechanisms, as determined by transmission electron microscopy (TEM), will be related to the microstructures as determined by TEM, scanning electron microscopy and atom probe tomography. This research was supported by the Thayer School of Engineering Innovation Ph.D. program and the US Department of Energy, Office of Basic Energy Sciences grant DE- SC0018962.

Contact : stephane.grenier@neel.cnrs.fr