It has been reported that the elimination of trace phosphor changes eutectic Si phases from a coarse plate-like structure to a fine structure in Al-Si alloys, thereby enhancing their mechanical properties, particularly ductility. In the present study, the damage initiation and growth behavior in Al-7%Si alloys with and without trace phosphor of 10ppm were investigated by employing an in-situ X-ray microtomography technique. High resolution 3D/4D observation and subsequent image-based analyses enabled the detailed assessment of the damage evolution behavior.
From the results, it was concluded that both initiation and growth of micro voids originating from particle fractures are effectively suppressed in phosphor-free alloys, allowing drastic improvement in both the strength and ductility. By eliminating trace phosphor, dominant particle fracture is effectively postponed to later loading steps. It can be inferred that mechanical properties can further be improved by controlling the existence and geometrical distribution of hydrogen micro pores in phosphor-free alloys.
