Nanoindentation and Cavitation-Induced Fragmentation Study of Primary Al3Zr Intermetallics Formed in Al Alloys

Abstract

Mechanical properties of primary Al3Zr crystals and their in situ fragmentation behaviour under the influence of a single laser induced cavitation bubble have been investigated using nanoindentation and high-speed imaging techniques, respectively. Linear loading of 10 mN was applied to the intermetallics embedded in the Al matrix using a geometrically well-defined diamond nano-indenter to obtain the mechanical properties at room temperature conditions. Primary Al3Zr crystals were also extracted by dissolving the aluminium matrix of an Al-3wt% Zr alloy. The extracted primary crystals were also subjected to cavitation action in deionized water to image the fracture sequence in real time. Fragmentation of the studied intermetallics was recorded at 500,000 frames per second. Results showed that the intermetallic crystals fail by brittle fracture mode most likely due to the repeatedly-generated shock waves from the collapsing bubbles. The results were interpreted in terms of fracture mechanics using the nanoindentation results.