含Zn,Ag或Sc的Al-Li-Cu-Mg-Zr合金正电子寿命谱研究

Positron Annihilation Lifetime Study of Al-Li-Cu-Mg-Zr Alloy with Doping Zn, Ag or Sc

关键词:  深低温  正电子寿命谱  Al-Li-Cu-Mg-Zr合金  缺陷  基体电子密度

Key words:  cryogenic temperature  position lifetime spectrum  Al-Li-Cu-Mg-Zr alloy  defects  bluk electronic density

摘要:

在深低温到室温的不同温度下,测量了不同时效状态的Al-Li-Cu-Mg-Zr合金和含Zn,Ag或Sc的Al-Li-Cu-Mg-Zr合金的正电子寿命谱。对e寿命谱特征参数的分析表明:峰值时效使热空位大量回复,缺陷的数目减少。在深低温下,空位主要以单空位形式存在且随温度升高而激活并运动复合成多空位。Zn或Ag的加入对空位的运动复合有束缚作用,而Sc却有助于空位的运动复合。所有实验样品低温下基体电子密度都比室温的高,W'相析出长大使合金基体的电子密度提高,而S'相析出则使合金基体的电子密度降低。Zn,Ag或Sc的加入都增加了基体电子密度,有利于合金强度的提高。

Abstract:

At the variant points from cryogenic to ambient temperature, the positron annihilation lifetime spetra. of Al-Li-Cu-Mg-Zr alloy and that added by Zn, Ag or Sc in different ageing conditions were measured. The analysis for characteristic parameters of e lifetime spectra showed that a large number of thermal vacancies were recovered during the peak-ageing process, which made the amount of defects decrease greatly. At the cryogenic temperature the vacancies were mainly monovacancies and they became activated and moved to combine into multivacancies with increasing temperature. The doping of Zn or Ag hindered the movement and combination of monovacancies but that of Sc was available to it. In addition, the bulk electronic density in all samples at low temperature was higher than that at ambient temperature. The precipitation and growth of W' (Al₃Li) phase particles increased the bulk electronic density, but the precipitation of S' (Al₃CuMg) phase particles decreased the bluk electronic density. The adding of Zn, Ag or Sc increased the bluk electronic density, so it was available to improve the strength of alloys.