Manufacturing Technology 2019, 19(4):552-558 | DOI: 10.21062/ujep/333.2019/a/1213-2489/MT/19/4/552

Effect of Zr on Selected Properties and Porosity of AlSi9Cu1Mg Alloy for the Purpose of Production of High-precision Castings

Dana Bolibruchová, Michal Kuriš, Marek Matejka

Faculty of Mechanical Engineering, Department of technological engineering, University of Žilina. Univerzitná 8215/1, 010 26 Žilina. Slovak republic

The effect of Zr was assessed on changes in the mechanical properties of the alloy under investigation by the addition of Zr with a graduated increase by 0.05 wt. % Zr. Experimental samples were cast into ceramic molds, half of which were hardened by precipitation after casting. The measured values indicate an improvement in the mechanical properties, especially in experimental alloys containing Zr ≥ 0.20 wt. %. In the evaluation of Rm, the most significant improvement occurred in the experimental alloy with the addition of Zr 0.25 wt. % after heat treatment and E in the experimental alloy with the addition of Zr 0.20 wt. % after heat treatment, as well. The effect of Zr in the AlSi9Cu1Mg alloy investigated was also analyzed for porosity. It can be concluded that the addition of Zr into alloys is manifested by an increase in gassing of experimental alloys, especially in variants containing Zr ≥ 0.15 wt. %. At a higher Zr content there was a significant increase in the DI density index and pore size. For higher amounts of Zr ≥ 0.20 wt. %, long acicular phases with slightly cleaved morphology are visible in the metal matrix. Exclusion of the Zr phase nuclei with regard (also) to the change of exclusion temperature can cause capture of hydrogen bubbles (pockets) and thus increase the gassing rate.

Keywords: AlSi9Cu1Mg, Ceramic mold, Al3Zr, Investment casting, Improvement of mechanical properties

Grants and funding:

VEGA 1/0494/17.
Alucast Ltd.
Nemak Slovakia Ltd.

Published: August 1, 2019  Show citation