Upcycling waste iron into high-performance Fe3Si-SiC-NbC in-situ nanocomposites enhances multiple properties during carbothermal reactions

Abstract

Abstract In this study, we are interested in reusing industrial waste to produce cost-effective Fe 3 Si intermetallic-based nanocomposites with excellent mechanical, thermal, and magnetic properties, fabricated through an in-situ carbothermal reaction during powder metallurgy sintering. Fe15Si5Nb (vol%) powder is milled with increasing proportions of activated carbon up to 8% using high-energy milling, then pressed into tablets and sintered in an inert gas. The microstructure and phase composition of the sintered sample were investigated with FESEM and XRD techniques. Moreover, physical, thermal, mechanical, and magnetic properties were studied. The results indicated that the particle size of the Fe 15 Si 5 Nb powder decreased with the addition of activated carbon during milling. After sintering, XRD results showed the formation of two phases: Fe₃Si and FeNb. Upon adding activated carbon, the FeNb phase dissolved, and ceramic phases, SiC and NbC, were formed. Furthermore, there was a marked improvement in both the thermal expansion coefficient (CTE) and mechanical properties, and also no breakdown of magnetic properties. The microhardness, strength, Young’s modulus, and CTE of the sample containing 8% activated carbon improved by approximately 69.81%, 33.95%, 21.77%, and 16.67%, respectively, compared to the base sample. Magnetization of the intermetallic base decreases from 28.12 to 26.20, 26.08, 23.65, and 21.98 emu/g, respectively, after incorporating 1%, 2%, 4%, and 8% activated carbon.