The metastable structure of hypereutectic Al–17·5Si alloy surface induced by high current pulsed electron beam

Abstract

For this study, several types of metastable structures were investigated for the high current pulsed electronic beam treated hypereutectic Al–17·5Si alloy. Metastable structures that were studied included nano-silicon particles, aluminium (Al)-based supersaturated solid solution, dislocation tangle and amorphous structure. One of the goals of this research was to provide a better understanding of the high current pulsed electronic beam induced formation of metastable structures’ super-rapid melting and solidification processes, as well as plastic deformation. Furthermore, the phase composition of modified layer remained unchanged and the majority of the aluminium and silicon (Si) diffraction peaks escalated after high current pulsed electronic beam treatment. The result of the microhardness test revealed that the microhardness of the Al matrix had improved markedly after high current pulsed electronic beam treatment, increasing by 56·2%. On the contrary, the microhardness of primary Si decreased slightly, reducing by 54%.

Keywords:

• Hypereutectic Al–17·5Si alloy
• High current pulsed electron beam
• Dislocation tangle
• Amorphous structure
• Nano-silicon