Investigation of the chemical vicinity of crystal defects in ion-irradiated Mg and a Mg-Al-Zn alloy with coincident Doppler broadening spectroscopy

[摘要] Crystal defects in magnesium and magnesium-based alloys such as AZ31 are of major importance for the understanding of their macroscopic properties. We have investigated defects and their chemical surrounding in Mg and AZ31 on an atomic scale with Doppler broadening spectroscopy of the positron annihilation radiation. In these Doppler spectra, the chemical information and the defect contribution have to be thoroughly separated. For this reason, samples of annealed Mg were irradiated with Mg ions in order to create exclusively defects. In addition, Al- and Zn-ion irradiation on Mg samples was performed in order to create samples with defects and impurity atoms. The ion-irradiated area on the samples was investigated with laterally and depth resolved positron Doppler broadening spectroscopy and compared with preceding SRIM simulations of the vacancy distribution, which are in excellent agreement. The investigation of the chemical vicinity of crystal defects in AZ31 was performed with coincident Doppler broadening spectroscopy by comparing Mg-ion-irradiated AZ31 with Mg-ion-irradiated Mg. No formation of solute-vacancy complexes was found due to the ion irradiation, despite the high defect mobility.

[发布日期] 2007-11-01

[关键词] POSITRON-ANNIHILATION;MAGNESIUM;AZ31;EVOLUTION