Internal Friction Investigation Of Reverse Martensitic Transformation In Oil-quenched Ni_(64)al_(36) Alloy

摘要

Low-frequency internal friction investigation of reverse martensitic transformation in oil-quenched Ni_(64)Al_(36) alloy has been carried out using a multifunctional internal friction apparatus from room temperature to 400 ℃ and additionally differentialrnscanning calorimetry and X-ray diffraction experiments were also completed. It has been shown that an internal friction peak presents at about 220 ℃ in the internal friction temperature curve during heating for the oil-quenched Ni_(64)Al_(36) alloy but not for the furnace-cooled Ni_(64)Al_(36) 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 incrcase with decreasing vibration frequency and increasing heating rate, being linearly direetly proportional to T/f. It has been suggested that the internal friction peak results from reverse martensitic transformation of L1_0→γ during heating and originates from martensitie transformation of γ →L1_0 during the subsequent cooling process. The influence of the thermal cycles on the transformation is not observed for the limited thermal eycles.