The MCF (Mitsubishi Cupro-Ferrous alloy) which can be used as the new material for marine propellers in place of conventional copper alloys has been developed. Although the static tensile strength of MCF is not so high, the alloy has the excellent corrosion and erosion resistance to sea water, and has the corrosion fatigue strength larger than or almost equal to that of nickel aluminium bronze. The MCF has the material features just appropriate for propellers which are used in polluted sea water, in which conventional copper alloy propellers may be deteriorated due to the sulphur attack, and the MCF will present a great contribution to the prevention against troubles concerning surface damage unavoidable in copper alloy propellers.