Investigation of the chemical vicinity of crystal defects in ion-irradiated Mg and AZ31 with coincident Doppler broadening spectroscopy

TL;DR

This study uses Doppler broadening spectroscopy to analyze the chemical environment of crystal defects in ion-irradiated magnesium and AZ31 alloys, revealing no solute-vacancy complexes despite high defect mobility.

Contribution

It introduces a detailed atomic-scale analysis of defect surroundings in Mg and AZ31 using advanced spectroscopic techniques and compares experimental results with simulations.

Findings

Excellent agreement between experiments and SRIM simulations.

No solute-vacancy complexes formed despite high defect mobility.

Chemical surroundings of defects characterized with coincident Doppler broadening spectroscopy.

Abstract

Crystal defects in magnesium and magnesium based alloys like 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 (DBS) 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 (CDBS) 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.