TY - THES

T1 - Influence of microalloying elements on the precipitation behavior of Al-Mg-Si alloys

AU - Werinos, Marion

N1 - embargoed until 26-06-2017

PY - 2012

Y1 - 2012

N2 - This work deals with a phenomenon called the negative effect of natural pre-aging on artificial aging, shown by many industrial important Al-Mg-Si alloys. An extensive literature research including the precipitation sequence in Al-Mg-Si alloys, fundamentals of vacancy assisted diffusion and theories treating the negative effect, served as a basis for the interpretation of experimental results. The approach of the work is based on a theory regarding interactions between the main alloying elements Si and Mg with quenched-in vacancies as the main reason for the negative effect of natural pre-aging on artificial aging. In the experimental part selected microalloying elements (Li, Ca, Sr, Ba, Ag, Cd, In, Ge, Sn, Sb, Pb and Bi) were added to the industrial important alloy AA6061. Some of these microalloying elements are believed to interact with vacancies in the aluminum matrix and are able to prohibit the negative effect of natural pre-aging on artificial aging. Using calculations from literature-based data of element-vacancy interactions in pure aluminum facilitated not only to verify the aforementioned theory, but also to interpret the effect which some tested microalloying elements exhibited on the overall precipitation kinetics of AA6061.

AB - This work deals with a phenomenon called the negative effect of natural pre-aging on artificial aging, shown by many industrial important Al-Mg-Si alloys. An extensive literature research including the precipitation sequence in Al-Mg-Si alloys, fundamentals of vacancy assisted diffusion and theories treating the negative effect, served as a basis for the interpretation of experimental results. The approach of the work is based on a theory regarding interactions between the main alloying elements Si and Mg with quenched-in vacancies as the main reason for the negative effect of natural pre-aging on artificial aging. In the experimental part selected microalloying elements (Li, Ca, Sr, Ba, Ag, Cd, In, Ge, Sn, Sb, Pb and Bi) were added to the industrial important alloy AA6061. Some of these microalloying elements are believed to interact with vacancies in the aluminum matrix and are able to prohibit the negative effect of natural pre-aging on artificial aging. Using calculations from literature-based data of element-vacancy interactions in pure aluminum facilitated not only to verify the aforementioned theory, but also to interpret the effect which some tested microalloying elements exhibited on the overall precipitation kinetics of AA6061.

KW - Aluminium Legierungen

KW - Al-Mg-Si Legierungen

KW - AA6061

KW - Negativer Kaltauslagerungseffekt

KW - Warmauslagerung

KW - Ausscheidungskinetik

KW - Leerstellen

KW - Diffusion

KW - Mikrolegierungselemente

KW - Element-Leerstellen Wechselwirkung

KW - Härte

KW - Atomsonden-Tomographie

KW - aluminum alloys

KW - Al-Mg-Si alloys

KW - AA6061

KW - negative effect of natural pre-aging

KW - artificial aging

KW - precipitation kinetics

KW - vacancies

KW - diffusion

KW - microalloying elements

KW - solute-vacancy interactions

KW - hardness

KW - atom probe tomography

M3 - Diploma Thesis

ER -