PURPOSE: To obtain a high-strength heat-resistant material having high-temp. strength and high hardness by subjecting an Ni-base alloy incorporated therein with a specific amt. of C, Cr and Al, Ti, etc. to soaking to the solutionizing temp. of a γ phase or above and to work hardening at the recrystallization temp. or below and further to age hardening.

CONSTITUTION: An Ni-base alloy contg. 0.01W0.20wt% C, 13.0W23.0% Cr, 1.5W 3.5% Ti and 0.1W4.5% Al (where ≥2.0% Ti+Al) is melted. The billet of such Ni-base alloy is soaked to the temp. above the solubilizing temp. of the γ phase [Ni3(Ti; Al)]. The billet is then work-hardened by ≥20% working at the recrystallization temp. or below and is age-hardened at 600W850°C in this state. The inter-granular precipitation of the γ phase is thereby accelerated and the η phase at the grain boundary is suppressed. This material is applicable to a material for the exhaust valve of an internal-combustion engine and a material for heat-resistant parts of a turbine, etc.