Investigating the Hall-Petch Constants for As-Cast and Aged AZ61/CNTs Metal Matrix Composites and Their Role on Superposition Law Exponent

AZ61/carbon nanotubes (CNTs) (0, 0.1, 0.5, and 1 wt.%) composites were successfully fabricated by using the stir-casting method. Hall–Petch relationship superposition of different strengthening mechanisms analyzed for aged as-cast AZ61/CNTs composites. Aged showed higher frictional stress (108.81 MPa) than that (31.56 Mpa) when grain size was fitted directly against experimentally measured yield strength. In contrast, considering all contributing mechanisms, constants contributed only grain-size found (σ0 = 100.06 Mpa Kf 0.3048 m1/2) 87.154 0.3407 law exponent is unity. The dislocation density maximum (8.3239 × 1013 m−2) in case AZ61/0.5 wt.%CNT composite, composites, it increased with increase CNTs concentration reached value (1.0518 1014 AZ61/1 composite.