PURPOSE: To provide the title cheap structural material made of aluminum nitride alloy obtd. by electrolytically nitriding an aluminum alloy, lighter than a Ti alloy, easy to form, cut and die forge, and mainly used as aircraft parts.

CONSTITUTION: An aluminum alloy as an anode is put into a salt bath contg. gaseous NaCN formed by dipping electrolytic Ti in a NaCN-dissolved bath, and a DC current is supplied to manufacture an aluminum nitride alloy. As a result, a deep nitrided layer is obtd., and the aluminum nitride alloy capable of strengthening not only the surface but up to the core of the aluminum alloy is used as a structural material for aircraft parts such as rivet, propeller, push rod, fluid transporting tube, bolt and nut. Since hardening of the aluminum alloy after the nitriding is gentle, the following effect is obtd.: press forming, punching, rough cutting and cutting, die forging, etc. are performed before age hardening after the nitriding.