Fabrication of AMHCs and testing of their properties with a view to develop improved materials for industrial applications has been an interesting topic for research for decades. The AMCs with one or more (multiple/hybrid) reinforcement are getting more interest than single reinforced composites because of improved properties. The very first research on the AMCs appears to have been taken up by S. Ray in 1968 as Masters’ dissertation at IIT Kanpur . But, the concept of hybrid composites appeared in early 1990s . Review of relevant research reported in literature has been presented below.
Lee et al. (2004) fabricated the Al-alloy based metal matrix composite by reinforcing the 20% of metallic amorphous (Ni–20.6Nb–40.2Ta) phase into Al-356 metal matrix using infiltration casting process, under argon pressure. The study reveals that the reinforcing metallic amorphous into Al-alloy improves the mechanical properties (compressive strength, hardness). The composite samples exhibit higher compressive yield strength (163 MPa) than that of the monolithic sample (129 MPa). The metallic amorphous phase ribbons are consistently distributed in the Al-alloy .
Dolata & Wieczorek (2007) fabricated the AMHCs using chromium carbide (Cr3C2) and titanium carbides (TiC) with 5–10% (by weight) through centrifugal casting and tested the wear behavior. The reinforced composites show the uniform wear mechanism than the base alloy. The composites with higher weight fraction (10%) of the carbide reinforcement shows the better wear behavior than the composite with 5% reinforcement. An increase in the reinforcing phase fraction allowed the elimination of the phenomena connected with adhesion wear .
Mahendra & Radhakrishna (2010) fabricated the hybrid composites using Al-4.5%Cu alloy as base matrix and combination of fly ash & SiC (5-10-15% by weight equal proportion) as the hybrid reinforcement, through stir casting. The mechanical properties (tensile strength, compression strength, and impact strength) and wear properties increase with increase in hybrid reinforcement, while decrease in the density of AMHC has been observed .
Boopathi el al. (2013) fabricated the hybrid composite using aluminium as base matrix and combination of SiC & fly-ash as the hybrid reinforcement through stir casting method. The weight fraction of fly ash (5% by weight) remains constant while SiC used as 5–10% (by weight) in hybrid reinforcement. It was observed that the tensile strength and hardness of the hybrid composites tends to increase while density and elongation of the composites decreases than base matrix. It was also observed that the hybrid composites of SiC and fly-ash shows improved properties than the single reinforced composites .
Moorthy et al. (2015) studied the tribological behavior using artificial neural network (ANN) modelling technique of the aluminium alloy (Al-2218) based hybrid composites by imparting the fly-ash (5, 10, 15 wt%) with 4 wt% of talc. The hybrid composites were fabricated through stir casting technique. It was noticed that the hybrid composites show the better wear characteristics than the base matrix. With adding fly-ash content, the wear performance also improves. The mixing of talc (4%) to form hybrid reinforcement plays significant role and displays better lubricity, which lower the wear rate .
Rao et al. (2017) examined the mechanical properties of Al-7075 based hybrid metal matrix composite using non-dominated sorting genetic algorithm (NSGA-II). The composite was fabricated by mixing the silicon carbide (SiC) and titanium dioxide (TiO2) particles in different weight fraction (%) combinations such as (0, 10), (2.5, 7.5), (5, 5), (7.5, 2.5) and (10, 0) respectively through stir casting. The optimum combination of SiC and TiO2 obtained under the best compromise solution has been found to be 9.513% and 0.487%, respectively. The results also indicate that among the two, SiC and TiO2, the fraction of SiC particle is the most influencing parameter to all the three mechanical properties .
Vinod et al. (2019) characterized the mechanical properties of the aluminium alloy (Al-356) based hybrid composites, in which combination of rice husk ash (RHA) & fly ash has been reinforced. The double stir casting process has been adopted for processing. It is observed that the hybrid reinforcements are homogeneously distributed through matrix and improves the mechanical properties of composites. Lower porosity is also observed in composites due to imparting of ceramic hybrid particles .
These studies highlight that the utilization of hybrid reinforcements in aluminium matrix hybrid composites generate better mechanical, physical and tribological properties. Al-4032 is a famous cast (Al–Si) alloy with high wear resistance, corrosion resistance and improved mechanical properties. In this study, the Al-4032 alloy-based hybrid composites have been fabricated through bottom poring stir casting machine. The mixture of SiC and granite marble powder (GMP) has been used as hybrid reinforcement with 0-3-6-9 weight% in equal proportion. The morphological (microstructure, SEM, XRD) and mechanical (tensile strength, impact strength and micro-hardness) characterization of the AMHC has been carried out. The mechanical properties of the AMHCs have been observed to be better than the unreinforced alloy.