Demir-mangan-aluminyum-nikel esaslı düşük ağırlıklı çelikler: Bor ilavesinin mikroyapı ve mekanik özelliklere etkisi

A novel medium entropy alloy (MEA) based on Fe-Mn-Al-Ni has been designed adopting HEAs phase formation rules, and the effects of minor addition of boron on phase content have been also investigated using both theoretical and computational approaches. Boron-free Fe(52.71-x)Mn31.11Al5.09Ni11.08Bx (x=0,0.05,0.2,0.5,0.7 wt%) MEA showed a single face-centered cubic (FCC) structure. XRD results indicated that with 0.05 and 0.2 wt% boron addition the system maintains its single-phase structure. Further boron addition leads to the formation of metal boride intermetallics by 4.62 and 6.14% of Fe2B intermediate phase in as-cast and 2.7 and 5.4% in D&H samples due to Rietveld Analysis for 0.5 and 0.7 wt% boron doped alloys respectively. Boron addition has positive effect on grain size reduction of the system where just by 0.05 wt % boron addition the grain size has been almost halved compare to boron free as-cast sample. Moreover, it is observed that as the boron level increases, the hardness value increases. The thermomechanical process resulted in increasing the yield strength by ~50% ( from 151 MPa to 222.5 MPa) and ultimate tensile strength by ~15% ( from 476 MPa to 543 Mpa)-both in 0.7 wt % boron doped alloy- at comparable ductility(Ԑ>60%).