Abstract: A porous metal having a much smaller ligament size is provided. The porous metal includes a crystal of an alloy, the alloy containing n or more kinds of elements, n being an integer of 3 or more, the alloy having a composition of each element of from {(100/n)?(75/n)) at % to {(100/n)+(75/n)} at %, and the porous metal having a ligament size of 220 nm or less. The alloy is preferably a high entropy alloy or a medium entropy alloy. In addition, the alloy preferably contains a solid solution of the respective elements.

Abstract: The invention relates to a method capable of enhancing both the antifouling properties of a high entropy alloy and also the mechanical properties thereof, without using chemical substances such as antifouling paints to prevent the attachment of animals and plants such as barnacles, mussels, sea lettuces, diatoms, etc., the method according to the invention being characterized by the use of severe plastic deformation to reduce the grain size in a high entropy alloy and thereby impart to the high entropy alloy a property of suppressing the attachment of aquatic or marine organisms, and according to the method, environmental issues caused by the use of antifouling paint, which is conventionally the most widely used method, may be resolved, and the energy efficiency of ships may be improved, thereby reducing societal and economic loss.