Effects of Temperature and Strain Rate on the Dynamic Mechanical Behavior of a Fine Grained Al-Sc Alloy

A rod gravity cast aluminum alloy of nominal composition Al-3.0Mg-0.8Sc-0.08Zr has been tested at high strain rates in tension and compression using a Split Hopkinson Pressure Bar. Peak aging heat treatments were performed in an attempt to grow secondary phase Al3Sc particles at grain boundaries to strengthen the alloy under high strain rate loads and at elevated temperatures. Electron backscattering diffraction and energy dispersive x-ray spectroscopy were performed for as cast and peak aged material conditions. Preliminary characterization results indicate negligible changes to the microstructure and second phase particles from the peak aging process performed in this study. Results show that the alloy's mechanical response to compression and tension at high strain rates is less sensitive at elevated temperatures when compared to a high strength 7010 aluminum alloy, providing further evidence of scandium's high temperature strengthening effects in aluminum alloys.