MICROSTRUCTURAL AND MECHANICAL CHARACTERIZATION OF THE THIXOCASTED ZK60-T6 MAGNESIUM ALLOY WITH RARE EARTH ELEMENTS

Marcus Vinicius Tavares Machado¹; Henrique Pinho Duarte²; Victor Eduardo Pinheiro da Silva³; Erenilton Pereira da Silva⁴; Antonio Luiz Ribeiro Sabariz¹; Haroldo Cavalcanti Pinto⁴

¹ Universidade Federal de São João del-Rei; ² University of Wisconsin - Madison; ³ Karlsruhe Institute of Technology; ⁴ Universidade de São Paulo, Escola de Engenharia de São Carlos

doi:10.20906/CPS/COB-2015-2390

Resumo

This paper aims to study the effects of the T6 thermic treatment composed by solubilization and artificial aging, in the microstructure and mechanical properties of the ZK60 Magnesium Alloy produced by thixocasting, with standard composition and also with the addition 1.5% in weight of rare earth. The results demonstrate that this casting process engender ingots with homogeneous chemical composition, free of pipes, blowholes and internal oxidation. Moreover, the microstructure of the alloy consists in a matrix of globular grains with heterogeneous shape, with the a-Mg phase reinforced by the precipitates Mg-Zn, Mg-Zn-RE and Mg-RE at the grain boundaries. Furthermore, the mechanical properties were tested using the Vickers micro hardness, comparing the results for the standard composition alloy, as casted and after the T6 treatment, as well for the alloy with rare earth, which presented a hardness increase after the thermal treatment.

Palavras-chave: Magnesium; Rare Earths; Casting; Semi-solids; T6