Challenges in optimizing the resistance to corrosion and wear of amorphous Fe-Cr-Nb-B alloy containing crystalline phases

The conflicting role of crystalline phase on the corrosion and wear resistance of the glass former Fe66Cr10Nb5B19 alloy was investigated. Amorphous to crystalline structures were produced by amorphous ribbons annealing and solidification of the liquid into a wedge-shaped copper mold. Amorphous and amorphous/nanocrystalline microstructures displayed good balance of properties. Their corrosion resistance remained elevated since α-(Fe,Cr) and (Fe,Cr)2B crystals were non-percolated within the corrosion-resistant amorphous matrix. Wear resistance was still high because (Fe,Cr)2B is even harder than the amorphous matrix. Crystalline microstructures were resistant against wear thanks to the large fraction of (Fe,Cr)2B and (Fe,Cr)NbB, both effective to protect the softer α-(Fe,Cr) matrix. Their corrosion resistance, however, was severely compromised, given the elemental partitioning to form crystals, with the interfaces more prone to corrode. While amorphous and amorphous/nanocrystalline microstructures presented the best-combined resistance to corrosion and wear, the crystalline microstructures are interesting for load-bearing applications where high corrosion resistance is not required.