快冷Fe-Al合金中的原子缺陷弛豫

在多功能内耗仪上用自由衰减和强迫振动方法研究了不同Al含量淬火Fe-Al合金中的两个弛豫型内耗峰.结果显示：P1(180℃)和P2(340℃)两个内耗峰只出现在淬火样品的加热过程中，而在随后的冷却过程中不出现.P1峰是由在α和β(或γ)点阵上的空位组成的最近邻双空位偶极子在应力诱导下的重新取向产生的，其弛豫强度随Al含量非单调地变化，在大约25% Al(原子百分比，以下同)处出现最大值.Al含量较低的Fe-Al合金无 关键词： 空位 弛豫 Al含量

Relaxation resulting from atomic defects in quenched Fe-Al alloys

Two relaxational internal friction peaks in quenched Fe-Al alloys with different Al content have been investigated using a computer-controlled automatic inverted torsion pendulum through free-decay and forced vibration method. It has been shown that the two peaks (P1, 180℃ and P2, 340℃) appear only in the heating process and do not appear in subsequent in-situ cooling process. It is suggested that P1 resulted from the stress-induced reorientation of di-vacancies, which consists of the reorientation of nearest neighbour Fe-vacancies on the α and　β (or　γ) sublattice sites. The relaxation strength of P1 varies im-monotonicly with Al content and there is a maximum at about 25% Al(atomic percent). There is no P1 peak in the Fe-Al alloys with lower Al content since vacancies exist in the form of isolated vacancies. When Al content is over 25%, the number of vacancies on β and　γ sites is reduced. Therefore, the nearest neighbour di-vacancies are decreased and the height of P1 peak declines. P2 originates from the stress-induced reorientation of Fe_Al-V_Fe dipoles under. P2 does not appear in the Fe-Al alloys with Al less than 22% since no Fe_Al anti-site atoms and Fe_Al-V_Fe dipoles are produced.