Effect of Ni Doping on Strength and Damping Capacity of Fe–Al Alloys

Abstract

Strength and damping capacity of Fe–Al alloys doped with different amounts of Ni were examined. Fe–Al alloys with an appropriate amount of Ni doping exhibited yield stress higher than 1 GPa and internal friction of above 0.032. In these alloys, the NiAl phase with the B2 structure densely precipitated in the Fe–Al matrix, satisfying the cube-on-cube orientation relationship. The precipitation of NiAl resulted in high strength, which was associated with the difference in primary slip systems between the NiAl precipitates and the Fe–Al matrix. Moreover, the internal friction measured under an external magnetic field showed low values, suggesting that Fe–Al alloys with the NiAl precipitates demonstrated magneto-mechanical damping caused by the irreversible motion of magnetic domain walls. The Al concentration in the Fe–Al matrix became appropriate for damping properties by the precipitation of NiAl, resulting in an increase in the internal friction of the alloy.