Improving the mechanical properties of the B319 aluminum alloy by addition of cerium

Abstract

The effect of cerium (Ce) addition (0.1, 0.3, 0.5, and 1.0 wt%) on the ambient and high-temperature mechanical properties of a commercially available B319 powertrain aluminum alloy was investigated. In addition, to characterize the effects that Ce has on the microstructure of the B319 alloy, field emission scanning electron microscopy, optical microscopy, X-ray diffraction, energy dispersive X-ray spectroscopy and X-ray micro computed tomography were employed. Statistical significance of the results was evaluated using the single-factor ANOVA analysis. The microstructural analyses revealed that Q-AlCuMgSi, α-Al, Al2Cu, eutectic silicon (Si), and Al15(Fe,Mn)3Si2 were present in all of the B319 and B319 + Ce specimens. However, the addition of Ce led to the formation of Al3Ce4Si6 and AlCeSi2 as well as a refinement of eutectic Si. It was found that, addition of 0.1 wt% Ce to the B319 alloy considerably increased the yield and tensile strength at ambient temperature (~10% and ~9%, respectively) and at 250 °C (~14% and ~7%, respectively) as well as the alloy's % elongation and micro hardness (~18–60% and 11%, respectively). However, it was observed that further addition of Ce (up to 1.0 wt %) results in a slight decrease in the materials tensile strength, as compared to the B319 + 0.1% Ce sample. This is presumed to be attributed to the escalating amount of porosity and needle-like Ce bearing intermetallics that were observed in the higher Ce content samples. The results from this study provide the automotive industry with a new cost-effective method of improving the mechanical properties of their currently used powertrain alloys, allowing for greater efficiency and improved performance.