Effect of Scandium in Al–Sc and Al–Sc–Zr Alloys under Precipitation Strengthening Mechanism at 350 °C Aging

In the present scenario, it is much needed of developing Al–Sc and Al–Sc–Zr alloys owing to its higher strength to weight for aerospace applications. The present study is dealt about effect of Scandium on micro hardness and micro structure of synthesized Al–Sc alloy and Al–Sc–Zr alloy under different weight percentage. The precipitation strengthening of as-cast structure, Al–Sc alloy and Al–Sc–Zr alloy have been analyzed during aging at 350 °C. From the experimental investigation, only little difference in micro hardness of developed alloys was observed during initial stage of aging. The peak hardness of Al–Sc–Zr alloy was maintained for a relatively longer period for producing better thermal stability. Three-dimensional atomic probing indicated that the precipitation of Zr in the precipitate at the initial stage of aging which can inhibit the growth of the precipitate’s size. TEM results showed that the Al–Sc–Zr alloy formed two precipitates of different sizes at the over-aging phase after the peak state of hardness.