New developments on optimizing properties of high-Zn aluminium cast alloys

International Symposium on Liquid Metal Processing & Casting 2015

材料科学;金属工艺学

Krajewski, W.K.^1 ; Buras, J.^1 ; Krajewski, P.K.^1 ; Greer, A.L.^2 ; Schumacher, P.^1 ; Haberl, K.^3

AGH University of Science and Technology, Faculty of Foundry Engineering, 23 Reymonta Street, Krakow

30-059, Poland^1

University of Cambridge, Department of Materials Science and Metallurgy, 27 Charles Babbage Road, Cambridge

CB3 0FS, United Kingdom^2

University of Leoben, Department of Metallurgy, Department of Casting Research, Franz- Josef-Strasse 18, Leoben

8700, Austria^3

关键词: Aluminium cast alloys;    Attenuation coefficient;    Coarse-grained structure;    Global economies;    Mechanical property measurements;    Micro-structural;    Primary dendrite;    Strength and elongations;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/143/1/012029/pdf
DOI  :  10.1088/1757-899X/143/1/012029

学科分类：材料科学（综合）

来源: IOP

【 摘 要 】

Foundry alloys with Al-based matrices have a wide range of uses in today's global economy and there is a high demand for castings of Al alloys, including Al-Zn alloys. In this paper, investigations on the grain refinement of high-Zn aluminium cast alloys are presented. Aluminium alloys with relatively high zinc content have a tendency to be coarse-grained, especially in the case of castings with low cooling rates such as are found in sand moulds. The coarse-grained structure degrades the plasticity, specifically the elongation. Therefore, for aluminium alloys of high (10-30 wt.%) zinc content, inoculation is attractive, aiming to break up the primary dendrites of the a-phase solid solution of zinc in aluminium. Such dendrites are the principal microstructural component in these alloys. On the other hand, a finer grain structure usually reduces the damping (e.g. as measured by attenuation of ultrasound) in these alloys. In the present investigations, a binary sand-cast Al-20 wt.% Zn alloy was inoculated with different additions of AlTi3C0.15 (TiCAl) and ZnTi-based master alloys. The sand-cast samples were subjected to mechanical-property measurements (tensile strength and elongation), image analysis to determine grain size, and measurements of the attenuation of 1 MHz ultrasound. It is found that both of the master alloys used cause significant refinement of the a-AlZn primary dendrites and change their morphology from linear-branched to semi-globular, increase the elongation by about 40%, and decrease the attenuation coefficient by about 25% in comparison with the initial alloy without inoculation.