Effect of Mo Element on Microstructure and Properties of Laser Powder Bed Fusion Co-Cr-Fe Alloy

Abstract:

Compositionally graded 15Co-25Cr-(60-x)Fe-xMo (x=0-5, wt%) specimens were fabricated by laser powder bed fusion (LPBF) using blended elemental powders of Co, Cr, Fe, and Mo, employing an in-situ alloying strategy. The compositional homogeneity, phase constitution, and microstructure of the specimens with different Mo contents were investigated. Furthermore, the influence of Mo content on the magnetic properties was elucidated by integrating experimental findings with first-principles calculations. The results indicate that all specimens achieve full alloying without defects such as porosity or un-melted particles. The magnetic properties exhibit a non-monotonic trend with increase in Mo content, initially enhancing before deteriorating. Optimal magnetic performance is obtained at the Mo content of 3wt%, yielding a coercivity () of 26.54 kA/m, a remanence () of 0.9 T, and a maximum energy product () of 11.56 kJ/m³. Additionally, Mo incorporation is found to enhance the microhardness of the alloys, with the 15Co-25Cr-57Fe-3Mo sample exhibiting a hardness of 424HV_0.5.