Creep resistant zinc alloys: Towards thermodynamic and mechanical stability by microalloying

点击翻译按钮获取中文摘要

The aim of this project is to provide new alloy design strategies for zinc alloys offering an improved creep resistance. To this end, a dual approach has been followed in a previous project, in which both the available thermodynamic data of the Zn-Al-Cu-(Mg) system as well as the microstructural and mechanical properties of respective alloys with different magnesium contents have been studied in detail, based both on a die-cast and several gravity cast alloys. The addition of magnesium has yielded some promising improvements in mechanical properties within this previous project. Therefore a proposal for a new project is made during which the successfully combined thermodynamic and microstructural/mechanical characterisation approach will be continued. The focus will be placed on the mechanisms of mechanical (in)stability and in particular on precipitation and decomposition phenomena by using high resolution characterization methods and modelling of the essential thermodynamic equilibrium states. While the investigation of deformation mechanisms will initially focus on micro- and nanomechanical testing at different strain rates and temperatures in correlation with TEM and APT in order to further elucidate the role of the individual microstructural components, the thermodynamic assessment will concentrate on a new alloying element, Ti, in order to provide guidelines for promising alloy compositions. Small-scale specimens produced by induction melting with rapid solidification will be used for both, nanomechanical and thermodynamic characterization. That allows an efficient joint experimental programme and also to capitalize on the combined insights from both parts of the project into how to improve the microstructure regarding the major components using the essential thermodynamic basis. Based on the acquired knowledge concerning deformation characteristics, precipitation and decomposition phenomena and the resulting mechanical properties of new Zn-Al-Cu-(Mg, Ti) alloys, the projects aims to provide future alloy design strategies for Zn alloys with improved mechanical stability and creep resistance.