Partial liquid metal dealloying to synthesize nickel-containing porous and composite ferrous and high-entropy alloys

Liquid metal dealloying is performed by immersing soluble and insoluble elements into a liquid metal bath but this prevents precise composition control. Here, the authors control the amount of soluble element remaining in the microstructure by partial dealloying and applied them to high-entropy alloys. Liquid metal dealloying is a promising technique to produce bicontinuous porous metals with high specific surface areas. This processing technique relies on the selective dissolution of a component from a precursor alloy into a metal bath while the remaining insoluble component self-assembles into an interconnected structure. However, it has not been applied to produce nickel-containing porous metals because of the lack of a suitable metallic bath. Here we show that nickel-containing porous metals can be produced by partial liquid metal dealloying. The amount of soluble component in the resulting microstructure can be tuned by carefully choosing the bath element so that the ligaments of desired composition equilibrate with the metal bath. We demonstrate this partial liquid dealloying concept using magnesium and bismuth baths and rationalize the results through thermodynamics calculations. Furthermore, we apply this technique to produce porous nickel-containing stainless steel and high-entropy alloy.