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High-permeability alloys of the composition 80-percent Ni, 4-percent Mo, remainder Fe, are generally used for recorder heads. The annealing temperature for highest initial permeability in such alloys is 2150°F. This high annealing temperature is not desirable for recorder head laminations since it makes the laminations too soft. Theoretical guidelines for calculating the necessary permeability of recorder head laminations are presented. The lowest possible annealing temperature, yielding sttfficient permeability and high hardness, can be selected from the given experimental data.