Layer-wise Graded Composites (LGCs) have spatially dependent properties, but the zone dependent machinability during drilling of such materials is not fully understood. This paper examines the microstructural, mechanical, and drilling properties of layer-wise graded 10 wt% Silicon Nitride (Si₃N₄) reinforced A356 Aluminium (Al) alloy cast through combined stir and vertical centrifugal molding and subsequent T6 heat treatment. The microstructural analysis showed a clear distribution of gradient having an outer zone of ceramic and an inner zone of matrix. The highest value of microhardness at 182 HV was measured in the ceramic concentrated layer, with an improvement rate of 73% in the matrix concentrated layer. Experiments on drilling were done using spindle rotational velocities of 1000–3000 rpm and feed per revolution of 50–150 mm/rev using High Speed Steel (HSS) and TiN-coated carbide tools. When using a TiN-coated tool, the interfacial area maximum Material Removal Rate (MRR) was 12.364 g/min at 3000 rpm and 150 mm/rev. At 1000 rpm and 50 mm/rev, a minimum surface roughness of 3.670 μm was achieved, with the consequences of Analysis of Variance (ANOVA) showing that feed per revolution had a contribution of 71.16% to the MRR and a contribution of 49.98% to the surface roughness by drill material. The findings prove that the TiN-coated tools are important in enhancing the machining performance and surface quality. This work supports UN SDG 9 and SDG 12 by promoting advanced manufacturing of durable, resource-efficient aluminium-based graded composites.
SINGH et al. (Wed,) studied this question.