Ni-Co-Nb-Si合金の減衰特性

Abstract

The effects of Nb and Si on the internal friction, coercive force, and mechanical properties of Ni-25 mass%Co-Nb-Si alloys have been investigated when either furnace-cooled or water-quenched after heating at 1273 K for 7.2 ks. The measurements of internal friction, hysteresis loop and mechanical properties were carried out by an inverted torsion pendulum method, an automatic recording fluxmeter and an Instron tensile testing machine.As the shear strain amplitude increases, the internal friction of these alloys first grows larger and reaches a maximum. Therefore, the maximum internal friction and the shear strain amplitude were defined as Qmax−1 and γc. The alloys containing no Nb showed the highest value of Qmax−1 at 3 mass%Si on furnace cooling and at 4 mass%Si on water quenching, respectively. The alloys containing 1 mass%Nb showed the highest value of Qmax−1, at 2 mass%Si on both cooling procedures. The γc, gradually lowered with decreasing Si concentration in these alloys. The alloys containing 3 mass%Nb were highest in Qmax−1 and lowest in γc at 2 mass%Si on both cooling procedures. The Qmax−1 alloys containing 5 mass%Nb was highest at 1 mass%Si on furnace cooling and lowest at 2 mass%Si on both cooling procedures.The coercive force Hc, also varied with Si concentration much like γc: both Hc, and γc, were small when Qmax−1 was large. This indicates a close relationship between the damping capacity and magnetoelastic properties of the alloys. Both tensile strength and yield strength rose with increasing Nb and Si concentrations. Elongation was independent of Si concentration and remained nearly constant.