Comparative Study of Microstructure, Mechanical and Reciprocating Wear Properties of Unmodified and Sr-Modified A383 Alloy and Composite

The present study focused on strontium (Sr)-induced A383 alloy and composite reinforced with 6 wt% boron carbide (B4C) particles processed by stir casting technique. From metallographic analysis, it was confirmed that Sr addition modified needle structures of α-Si to fine α-Si. This grain refinement enhanced the hardness of A383-Sr alloy by 52.72% and A383-Sr/B4C by 73.6%, and tensile strength of A383-Sr by 69.93% and A383-Sr/B4C by 81% when compared to A383 unmodified alloy. Fractography analysis proved that both Sr-induced alloy and composite had brittle failure with clear formation of flakes and cleavages. Reciprocating wear test was conducted at various loads (15 N, 25 N, 35 N) and at sliding distances (500 m, 1000 m, 1500 m). It was observed that wear rate was proportional to the applied load. Wear rate increased with increase in sliding distance, but after 1000 m, there was decline in wear rate. Worn surface analysis revealed the presence of oxide layer after 1000 m which enhanced wear resistance. A383-Sr/B4C composite possessed superior wear resistance compared to other.