Ultrafine alloy particles, and process for producing the same

A process for producing ultrafine alloy particles comprising an alloy including a primary metal and two or more subsidiary metals, comprising the steps of:

• introducing powder materials for producing said ultrafine alloy particles into a thermal plasma flame under reduced pressure to form a vapor-phase mixture, said powder materials including said primary metal and said two or more subsidiary metals solid-soluble in said primary metal and a content of said two or more subsidiary metals being in a range of 1 wt % to 25 wt %;
• and
• introducing a cooling gas toward an end portion of said thermal plasma flame in a supply amount sufficient for quenching said vapor-phase mixture so as to generate said ultrafine alloy particles capable of inhibiting coalescence or oxidation, or both, of said ultrafine alloy particles including said primary metal and said two or more subsidiary metals.