Magnetomechanical and Structural Internal Friction in Ni-Mn-In-Co Metamagnetic Shape Memory Alloy

摘要

The strain amplitude-independent and strain amplitude-dependent components of the internal friction in a Ni_(45)Mn_(36.7)In_(13.3)Co_5 metamagnetic shape memory alloy have been studied as function of temperature, strain amplitude and polarizing magnetic field. For ultrasonic oscillation frequency (91 kHz) and low strain amplitudes (10~(-7) -10~(-5)), the experimental results show that the internal friction in the ferromagnetic austenite is much higher than in non-magnetic martensite. We suggest that this unusual relationship is due to a high contribution of the magnetomechanical component to the internal friction of the ferromagnetic austenite.