Microstructure and Impression Creep Behavior of Al–7Si–0.3Mg Alloy with Zr Addition

The effect of 0.25 wt% and 0.5 wt% Zr addition on the impression creep behavior of the cast A356 alloy was investigated. Optical and scanning electron microscopy (SEM) equipped with energy dispersive spectrometry (EDS) were used for examination of the microstructure. The impression creep test was conducted at the temperature range of 493–553 K under the stress range of 480–680 MPa (corresponding to the normalized stresses between 0.022 and 0.03). Microstructural investigations showed that the Zr addition refined the α-Al grains and modified the eutectic structure. The Zr-containing alloys were characterized by Zr-rich intermetallics, suggesting the creep resistance of the A356 alloy was improved by Zr addition. The creep resistance of the A356–0.25Zr alloy was higher than that of the A356–0.5Zr alloy that was attributed to the morphology and the distribution of intermetallics that are rich in Zr. Results showed that the lattice self-diffusion climb-controlled creep was the dominant creep mechanism in all alloys. Graphic Abstract