Investigation on Microstructure, Mechanical Properties and Fracture Mechanism of Trimodal SiC Reinforced Al5083/Al2024 Aluminum Alloy Based Nanocomposites Fabricated by Mechanical Milling and Hot Extrusion Processes

Abstract

The prime objective of this study is an investigation on the effects of mechanical milling process, incorporation of silicon carbide reinforcement phase and different amounts and types of coarse-grained aluminum powders (30 and 50 wt% unmilled Al5083 and Al2024) on microstructure, mechanical properties and fracture behavior of trimodal SiC reinforced Al5083/Al2024 aluminum alloy matrix nanocomposites. These composites were prepared through mechanical milling and hot extrusion processes. Results indicated that nanocrystalline structures of Al5083 alloy and Al5083–5 wt%SiC composite powders were formed during mechanical milling time of 50 h. Al5083–5 wt%SiC nanocomposite sample revealed strength and hardness superior to the coarse-grained aluminum sample. However, its elongation decreased down to a minimum value of 0.98%. Addition of 30 wt% unmilled Al2024 particles to the nanocomposite powder caused considerable improvement in the ductility, slight decrease in strength and hardness values and change in fracture mechanism from brittle to brittle-ductile mode, compared to that of Al5083–5 wt%SiC nanocomposite sample.