Abstract
Al matrix composite, reinforced with the in situ synthesized 3C–SiC, MgAl2O4, and MgO grains, was produced via the casting process using phenolic resin pyrolysis products in flash mode. The contents and microstructure of the composites’ fracture characteristics were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Mechanical properties were tested by universal testing machine. Owing to the strong propulsion formed in turbulent flow in the pyrolysis process, nano-ceramic grains were formed in the resin pyrolysis process and simultaneously were homogeneously scattered in the alloy matrix. Thermodynamic calculation supported that the gas products, as carbon and oxygen sources, had a different chemical activity on in situ growth. In addition, ceramic (3C–SiC, MgAl2O4, and MgO) grains have discrepant contents. Resin pyrolysis in the molten alloy decreased oxide slag but increased pores in the alloy matrix. Tensile strength (142.6 ± 3.5 MPa) had no change due to the cooperative action of increased pores and fine grains; the bending and compression strength was increasing under increased contents of ceramic grains; the maximum bending strength was 378.2 MPa in 1.5% resin-added samples; and the maximum compression strength was 299.4 MPa. Lath-shaped Si was the primary effect factor of mechanical properties. The failure mechanism was controlled by transcrystalline rupture mechanism. We explain that the effects of the ceramic grains formed in the hot process at the condition of the resin exist in mold or other accessory materials. Meanwhile, a novel ceramic-reinforced Al matrix was provided. The organic gas was an excellent source of carbon, nitrogen, and oxygen to in situ ceramic grains in Al alloy.
Highlights
Ceramic-reinforced aluminum matrix composites play a significant role in structural applications as high specific strength, stiffness, and specific modulus [1]
The innovative fabrication methods have focused on the interface which has been promoted a large improvement on the mechanical properties of ceramic-reinforced Al matrix composites; for instance, accumulative roll bonding [10,11], powder metallurgy technique [12,13], liquid metal infiltration [14,15], selective laser melting [16,17], plasma spraying [18,19], in situ growth [20,21], and special casting
The demand for the high plastic deformation of the matrix in roll bonding, the complex pretreatment of surface modification in powder metallurgy and liquid infiltration, surface hardness improved in plasma spray, the absence of suitable carbon source in the in situ process, or the need for complex equipment in special casting, are among the many limitations of these routes which are obvious
Summary
Ceramic-reinforced aluminum matrix composites play a significant role in structural applications as high specific strength, stiffness, and specific modulus [1]. SiC/Al matrix composite, as the most successful ceramic-reinforced Al matrix composites struggled with these conundrums in recent decades [2,3] Efficient approaches, such as the addition of alloying elements [4,5], surface modification [6,7], and novel fabrication processes [8,9] can be used to improve wettability and regulate interfacial reactions. The casting process, the most frequently used process in metal fabrication, provides the simplest and the most convenient preparation of Al matrix composites [22] It still restricts the application and fabrication of ceramic-reinforced Al matrix composite owing to weak wettability and dispersion. The organic gas is an excellent source of carbon, nitrogen, and oxygen to in situ ceramic grains in Al alloy
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