Enrichment of Surface Morphology and Mechanical Behaviour of Magnesium Alloy Composite Made With Hybrid Reinforcements Via Vacuum-Aided Stir Cast Process

A hybrid magnesium matrix composite reinforced with
aluminum, zinc, and multiple particulates was developed
through liquid stir casting to enhance tribo-mechanical
performance for potential applications in automotive
housings and structural frames. However, conventional stir
casting often results in reinforcement agglomeration porosity due to gas entrapment and oxide formation, and
non-uniform particle distribution, which limit composite
performance. This study aims to enhance the functional
characteristics of an AZ91 magnesium alloy by incorpo-
rating nanoscale silicon carbide (SiC, 50 nm) and gra-
phene (0.5 lm in length, 30 nm thick) as reinforcements. A
vacuum-assisted stir casting process was employed, with a
constant stirring rate and argon shielding to minimize
oxidation and promote uniform dispersion of the material.The synthesized AZ91-based composite contained 0.5 wt.%
graphene and 2–6 wt.% nano-SiC. The effects of vacuum-
assisted casting and hybrid reinforcement on the
microstructure (as observed via scanning electron micro-
scopy), mechanical properties (including tensile strength,
elongation, Vickers hardness, and energy absorption), and
density/porosity were evaluated and compared with those
of the unreinforced AZ91 alloy. Microstructural analysis
revealed improved dispersion and interfacial bonding
between SiC and graphene within the matrix under vac-
uum. The AZ91–0.5 wt.% graphene 6 wt.% SiC nanocomposite exhibited superior properties, including a
tensile strength of 303 MPa, hardness of 105 HV, energy
absorption of 13.7 J, and a reduced porosity level of 0.7%.
These enhancements demonstrate the potential of the
developed hybrid nanocomposite for applications like
structural components in the automotive sector.