In-situ Modification of a High Entropy Alloy with 2.4% Molybdenum Using LPBF, and Its Effect on Microstructure and Corrosion Resistance




Ritchie, M.
Mehraban, S.
Brown, S.G.R.
Butcher, D.
Cullen, J.
Calvo-Dahlborg, M.
Lavery, N.P.

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Laser powder bed fusion (LPBF) components display higher porosity compared to parts made by conventional processes and these pores act as preferential initiation sites for pitting corrosion to occur. In stainless steels such as 316L, molybdenum is 3.5X more effective at enhancing the pitting resistance than chromium, without adding unwanted nitrides to the alloy. In this work, the effect on corrosion resistance is reported for an Al-Cr-Mn-Ni-Fe high entropy alloy (HEA) gas atomised specifically for LPBF, as well as the effects of modifying the alloy by blending the HEA with molybdenum. In-situ LPBF processing, even for low levels of additions has made the comparison difficult, as the pitting resistance is so strongly linked to the porosity, which is higher in the in-situ process. Pitting resistance for both the original HEA and the doped HEA will be compared between samples processed by casting and by LPBF.


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