Investigation of Nanoscale Phase Formation in Rapidly Solidified Fe₂₀Co₂₀Ni₂₀Cr₂₀B_20−xSi_x Alloys

Abstract

In this study, nanoscale phase formation in rapidly solidified Fe₂₀Co₂₀Ni₂₀Cr₂₀B_20−xSi_x alloys was investigated using atom probe tomography (APT) and transmission electron microscopy (TEM). According to previous X-ray diffraction measurements and scanning electron microscopy with energy-dispersive X-ray spectroscopy results, it was thought that this alloy system was composed of almost a single face-centered cubic (FCC) solid solution phase when the Si content was 5 at.%. However, APT and TEM results at the nanoscale showed that both an FCC solid solution and compound phases formed for all alloy compositions. The rapidly solidified alloy ribbon with a Si content of 5 at.% showed the presence of nanoscale FCC and Cr₂B phases. Furthermore, in addition to the nanoscale FCC and Cr₂B phases, a nanoscale Cr₃Ni₅Si₂ phase was observed when the Si content exceeded 7.5 at.%.

Projected atom maps of Fe₂₀Co₂₀Ni₂₀Cr₂₀B₁₅Si₅ alloy.