Mechanical performance and EDM machinability of ZrO ₂ -reinforced Al7075 MMCs fabricated via powder metallurgy: investigation of dimensional deviation and MRR

This novel work is based on the mechanical properties and EDM machinability evaluation of Al7075 composites with different contents of ZrO2 invented by the powder metallurgy process and optimisation performed by Taguchi design approach. The following machining parameters were taken into account: the discharge current (1–4 A), the pulse-on time (50–62 μs), the pulse-off time (15–30 μs) and the content of ZrO2 reinforcement (1.5–4.5 wt%). Dimensional deviation (DD) and material removal rate (MRR) were chosen as performance responses. The results revealed that the composite containing 4.5 wt% ZrO2 showed the best mechanical properties, with an increase of around 19.36% in strength and higher hardness compared to other alloys. The reinforcement content and the machining parameters had a significant influence on the machining performance. The ZrO2 content is the most significant parameter that affects MRR, followed by voltage and pulse-on time, while current appears as the least significant parameter within the investigated range through the signal-to-noise ratio analysis. The best result for minimal dimensional deviation was achieved at 3 A current, 54 μs pulse-on time, 20 μs pulse-off time, and 1.5 wt% ZrO2 content. The results show that lightweight Al7075-based composites have good mechanical properties and better EDM machinability.