Microscopical Characterization of Cast Hypereutectic Al-Si Alloys Reinforced with Graphene Nanosheets

Abstract

This paper illustrates the effects of stirring and graphene nanosheet (GNS) addition on the microstructure and mechanical behaviour of 393 hypereutectic Al-Si alloys used in the diesel engine pistons. Two processing routes were applied to fabricate hypereutectic Al-Si alloys: The first route mainly depends on stirring Al-Si alloys for 12 minutes at 400 rpm. The second one involves stirring Al-Si alloys for 2 minutes and then adding graphene nanosheets into the vortex, and consequently continue stirring for 10 minutes at 400 rpm. Results show that the distribution of the primary silicon was improved significantly in stir casting at both the edge and the center of the samples with relative reduction of 34% and 37% in the average particle size respectively. This average primary silicon size was further reduced by 17% with the addition of 1 wt% GNSs. GNS embedding into Al-Si alloy matrix resulted in remarkable increase in hardness values of the nanocomposites compared to the cast alloy.

Microstructure and Mechanical Properties of Carbon Fiber Phenolic MatrixComposites containing Carbon Nanotubes and Silicon Carbide

“…should increase the relative improvement in the mechanical properties provided their uniform dispersion and efficient load transfer. This agrees with the results of [19][20][21]. Moreover, a significant improvement is expected to be observed in tensile strength of composites, as discussed above.…”

Some Modern Methods of Improving the Properties of Hypereutectic Al–Si Alloys

“…Оптична мікроскопія показала зменшення розміру частинок первинного кремнію та модифікування кремнію евтектичного внаслідок перемішування в процесі тверднення. В роботі [34] розтоп Al-22Si-0,4Mg перемішувався в процесі охолодження протягом 12 хв. при 400 об./хв.…”

A review of hypereutectic aluminum piston materials

“…Highest ultimate tensile strength and hardness are observed for the hybrid composite [21]. Another hypereutectic AlSi composite, with base of Al22Si alloy, reinforced with graphene (0.25 and 1%), is manufactured by stir casting by vortex method in [23]. Hardness of specimens was measured at edge and center of the casted cylinders.…”