铝一镁合金中的反常位错内耗峰

Al-0.03at％ Mg合金在倒扭摆上-65℃在原位进行拉伸,形变量为0.5％,然后在升温过程中测量内耗,于-30℃及60℃附近观测到内耗峰,随后从80℃的降温过程中仍在相同温度观测到内耗峰。研究了不同温度下的内耗-振幅曲线,在降温过程中出现内耗峰的温度范围内观测到了振幅内耗峰,并由此计算得到等效激活能分别为0.32及0.22eV。初步认为,当低温冷加产生的位错弯结在外力作用下作沿边往复运动时,“镁原子-空位”对和镁原子被拖曳运动是分别引起-30℃峰和60℃峰的可能的原因。 关键词：

DISLOCATION INTERNAL FRICTION PEAKS WITH ANOR- MALOUS AMPLITUDE EFFECT IN Al-Mg ALLOY

Two low frequency internal friction peaks have been observed at 243 K and 333 K respectively in Al-0.03 at% Mg alloy during the process of temperature going up after the specimen was stretched in situ with a tensile strain of 0.5% at 208 K. Such two peaks appeared also at the same temperatures when the measurement was made in the subsequent cooling from 353 K. The dependence of internal friction on the amplitude was determined and the amplitude internal friction peaks were observed in the temperature range of the peaks. The relationship between these two kinds of peaks was analysed and the effective activation energies of the temperature internal friction peaks were found to be about 0.32 eV for the 243 K peak and 0.22 eV for the 333 K peak. It was suggested that the two peaks at 333 K and 243 K may be respectively associated with the dragging of the solute atoms and the "Mg atom-vacancy" pairs, which may be produced through the sidewise motion of the kinks on the dislocations formed during the low temperature cold working.