Search

Magnesium matrix composites are essential lightweight metal matrix composites, following aluminum matrix composites, with outstanding application prospects in automotive, aerospace lightweight and biomedical materials because of their high specific strength, low density and specific stiffness, good casting performance and rich resources. However, the inherent low plasticity and poor fatigue resistance of magnesium hamper its further application to a certain extent. Many researchers have tried many strengthening methods to improve the properties of magnesium alloys, while the relationship between wear resistance and plasticity still needs to be further improved. The nanoparticles added exhibit a good strengthening effect, especially the ceramic nanoparticles. Nanoparticle-reinforced magnesium matrix composites not only exhibit a high impact toughness, but also maintain the high strength and wear resistance of ceramic materials, effectively balancing the restriction between the strength and toughness. Therefore, this work aims to provide a review of the state of the art of research on the matrix, reinforcement, design, properties and potential applications of nano-reinforced phase-reinforced magnesium matrix composites (especially ceramic nanoparticle-reinforced ones). The conventional and potential matrices for the fabrication of magnesium matrix composites are introduced. The classification and influence of ceramic reinforcements are assessed, and the factors influencing interface bonding strength between reinforcements and matrix, regulation and design, performance and application are analyzed. Finally, the scope of future research in this field is discussed. [ABSTRACT FROM AUTHOR]

Nano-SiC particulates (n-SiC) reinforced Mg-8Al-1Sn (AT81) composites with different volume fractions (0, 0.25, 0.5 and 1.0 vol.%) were fabricated by powder metallurgy process (P/M) combined with hot extrusion. The mechanical properties of the composite increased as the n-SiC content increased until the n-SiC content exceeded 0.5 vol.%, at which point they began to decrease. For this reason, the 0.5 vol.% n-SiC/AT81 composite was considered optimal. The 0.2% offset yield strength (YS), ultimate tensile strength (UTS) and elongation (ε) of 0.5 vol.% n-SiC/AT81 composites increased from 175, 318 MPa and 4.5% to 239, 381 MPa and 8.3%, respectively, compared to AT81. Both, the strength and plasticity of the 0.5 vol.% n-SiC/AT81 composites were improved as well. The improvement in mechanical properties can be attributed to the progressively refined matrix grain size, relatively uniform distribution of n-SiC and the well-bonded interfaces between n-SiC and the matrix. [ABSTRACT FROM AUTHOR]

Using freeze casting and pressureless infiltration methods, we prepared lamellar Al−Si−Mg/Al 2 O 3 −ZrO 2 composites with initial ceramic loading of 30 vol% and different Al 2 O 3 :ZrO 2 weight ratios (Al 2 O 3 :ZrO 2 =1:9, 3:7, 5:5, 7:3 and 9:1). The resultant composites inherited the lamellar structure of the Al 2 O 3 −ZrO 2 scaffolds, and the thickness of both metal and ceramic layers showed a trend of first increase and then decrease with increasing Al 2 O 3 content. During pressureless infiltration, multiple chemical reactions took place between ZrO 2 and the Al−12Si−10Mg alloy and the main reaction products were (Al 1−m , Si m ) 3 Zr, Al 2 O 3 and ZrSi 2 phases. The degree of the reaction depended on the ZrO 2 content in the ceramic composition. In general, the compressive strength of the composites decreased with increasing Al 2 O 3 content, but three-point bending strength showed a first decrease and then increase. When Al 2 O 3 :ZrO 2 =1:9, the compressive and bending strength of the composites reached about 997±60 MPa and 426±10 MPa, respectively. A simple model was proposed to illustrate the fracture mode and toughening mechanism of the composites. [ABSTRACT FROM AUTHOR]

• 66 wt% carbon fiber reinforced PEEK composite with strong interface was prepared. • The composite has ultra-high specific strengths exceeding majority of polymer or metal matrix composites. • The wear rate of composite is 1–2 orders of magnitude lower than materials with lubricating particles. • Excellent properties are attributed to high-mass carbon fibers and self-lubricating of composite. • A new idea is provided for the application of high-strength resin-based composite. It remains challenging to incorporate high-content fibers in fiber-reinforced polymer matrix composites to significantly enhance their mechanical properties. This work prepared polyether ether ketone (PEEK) matrix composite reinforced with 66 wt% carbon fibers with 0°/90° prepreg layer by compression molding, with aim to further increase the carbon fibers content in PEEK-based composites to improve the mechanical and wear properties at different temperatures, especially high temperature. The composite exhibits tensile and flexural strength of both exceeding 1000 MPa at room temperature, 810 ± 10 MPa and 521 ± 12 MPa at 200 °C and 458 ± 22 MPa and 290 ± 18 MPa at 300 °C, respectively. Especially at 300 °C, the composite demonstrates specific strength of 290 MPa/(g/cm3), which is superior to many magnesium or aluminum alloys (18–86 MPa/(g/cm3)). Further, the composite has a lower wear rate (5.47–12.80 × 10−7 mm3/Nm) at 200 °C by 1–2 orders of magnitude that of some materials with lubricating particles, and the wear surface is dominated by mild adhesive wear instead of abrasive wear at room temperature. The ultra-high mechanical and friction wear properties are attributed to the high content of staggered 90° carbon fibers, great interface bonding between the fibers and PEEK matrix, and self-lubricating effect of fibers and PEEK particles in the composite. This opens up a new performance level and provides a new idea for high-temperature applications of high-strength fiber-reinforced resin matrix composites. [ABSTRACT FROM AUTHOR]

2014 aluminum matrix composites reinforced with untreated (P-CNTs) and carboxyl-functionalized carbon nanotubes (C-CNTs) were successfully fabricated by the combination of sintering and hot extrusion. It is revealed that the C-CNTs are easier to disperse compared to the P-CNTs. Interfacial analysis indicated that a thin layer of aluminum carbide (Al 4 C 3 ) exists at the interface between the matrix and the P-CNTs. However, no obvious transition layers of Al 4 C 3 were observed at the interface of C-CNTs and 2014Al matrix in composites. Also, no preferred interfacial crystallographic orientation relationship between the C-CNTs and aluminum matrix was observed. Furthermore, C-CNTs have a larger effective interfacial contact with aluminum matrix compared to the untreated CNTs, due to large amount of –COOH group and defects on the surface of the C-CNTs interacting with Al by strong chemical and physical interactions. These aspects in turn affect the mechanical properties of the composites. The ultimate tensile strength of the composites were raised from 530 to 600 and 630 MPa with 0.5 wt.% of P-CNTs and C-CNTs, respectively. It reveals that the C-CNTs are more effective in strengthening the aluminum matrix than the P-CNTs. [ABSTRACT FROM AUTHOR]