Novel technique for the synthesis of ultra-fine porosity metal foam via the inclusion of condensed argon through cryogenic mechanical alloying

It was discovered that mechanical milling of metal powders in an ultra high purity argon atmosphere at cryogenic temperatures can result in argon being incorporated into the metal. This incorporated argon causes expansion by increasing the porosity when the material is annealed. The resulting annealed material can be classified as metal foam due to its highly porous nature. The most porous samples were measured to have nearly 50% porosity. This effect was observed in nominally pure copper and an alloy of 81 at% palladium and 19 at% zirconium.