Internal friction investigation of reverse martensitic transformation in oil‐quenched Ni64Al36 alloy

Abstract

AbstractLow‐frequency internal friction investigation of reverse martensitic transformation in oil‐quenched Ni64Al36 alloy has been carried out using a multifunctional internal friction apparatus from room temperature to 400 °C and additionally differential scanning calorimetry and X‐ray diffraction experiments were also completed. It has been shown that an internal friction peak presents at about 220 °C in the internal friction–temperature curve during heating for the oil‐quenched Ni64Al36 alloy but not for the furnace‐cooled Ni64Al36 alloy. The peak still appears during cooling and the peak temperature shifts to lower temperature. The changes of the peak temperature positions cannot be visibly observed when the vibration frequency is changed. The peak heights increase with decreasing vibration frequency and increasing heating rate, being linearly directly proportional to $ \dot T / f $ It has been suggested that the internal friction peak results from reverse martensitic transformation of L10 → γ during heating and originates from martensitic transformation of γ → L10 during the subsequent cooling process. The influence of the thermal cycles on the transformation is not observed for the limited thermal cycles. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)