Paper: In-Situ Alloying of CoCrFeNiX High Entropy Alloys by Selective Laser Melting
Authors: Farquhar, L., Maddison, G., Hardwick, L., Livera, F., Todd, I., Goodall, R.
High-entropy alloys typically use different metals mixed in roughly equal proportions leading to a large number of potential compositions.
Faster alloy development methods are desirable to speed up the investigation of new alloys.
The authors explore one such method, in-situ alloying during additive manufacture. A powder of a pre-alloyed composition is mixed with the powder of an additional element. Alloying takes place when the powders are melted during the additive manufacturing process.
To test the approach the authors used selective laser melting (SLM) to alloy in-situ copper and titanium powders with pre-alloyed CoCrFeNi powders.
The resulting samples were characterised for microstructure and phase composition.
The paper states: “It has been shown that in-situ alloying could be a useful tool with which to develop novel alloys quickly.
“In the future, further work involving heat treatments of in-situ alloyed samples could possibly result in a more homogeneous microstructure, therefore expanding the range of elements which could be added and alloyed successfully.”
Results showed the success of in-situ alloying is dependent on the melting point of the additional element compared to the base alloy, along with the tendency of that additional element to segregate in that alloy.
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“Back Scattered Electron images & accompanying Energy Dispersive X-ray Spectroscopy scans of alloys. EDS point scans showing the variation in concentration of Cu and Ti have also been shown, where all other elements remained equiatomic.” (CC BY) Farquhar et al. (2022).
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