In situ monitoring of artificial aging and solution heat treatment of a commercial Al-Mg-Si alloy with a high intensity positron beam.
JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020;
32:085705. [PMID:
31698341 DOI:
10.1088/1361-648x/ab556d]
[Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Microstructural changes of a commercial Al-Mg-Si alloy were studied during artificial aging by in situ Doppler broadening spectroscopy using a high-intensity positron beam. The in situ positron annihilation characteristics at high temperatures differ considerably from the conventionally applied ex situ measurements at low temperatures. Therefore, a more comprehensive view of precipitation processes in Al-Mg-Si alloys is obtained. Further, in situ positron-electron annihilation techniques allow for an investigation of aging processes with increased sensitivity. For the artificial aging temperatures of 180 °C and 210 °C pronounced variations of the Doppler broadening S-parameter reveal (i) the evolution of clusters into larger precipitates and (ii) the time of the formation of [Formula: see text]" precipitates and the role of vacancies in connection to this. Towards higher aging times, the transformation from coherent [Formula: see text]" to semi-coherent [Formula: see text]' precipitates could be verified. Additional insights are gained by in situ measurements of the S-parameter during the solution heat treatment of the previously overaged sample. Here, the S-parameter reveals both the dissolution of precipitates starting from temperatures of 364 °C and the thermal generation of vacancies.
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