Microstructure and mechanical behavior of metallic glass fiber-reinforced Al alloy matrix composites

Abstract

Metallic glass-reinforced metal matrix composites are an emerging class of composite materials. The metallic nature and the high mechanical strength of the reinforcing phase offers unique possibilities for improving the engineering performance of composites. Understanding the structure at the amorphous/ crystalline interfaces and the deformation behavior of these composites is of vital importance for their further development and potential application. In the present work, Zr-based metallic glass fibers have been introduced in Al7075 alloy (Al-Zn-Mg-Cu) matrices using spark plasma sintering (SPS) producing composites with low porosity. The addition of metallic glass reinforcements in the Al-based matrix significantly improves the mechanical behavior of the composites in compression. High-resolution TEM observations at the interface reveal the formation of a thin interdiffusion layer able to provide good bonding between the reinforcing phase and the Al-based matrix. The deformation behavior of the composites was studied, indicating that local plastic deformation occurred in the matrix near the glassy reinforcements followed by the initiation and propagation of cracks mainly through the matrix. The reinforcing phase is seen to inhibit the plastic deformation and retard the crack propagation. The findings offer new insights into the mechanical behavior of metal matrix composites reinforced with metallic glasses.Al-based metal matrix composites (MMCs) belong to a technologically attractive class of materials with low density, high specific strength and high wear resistance 1 . Improved mechanical properties can be achieved by combining the properties of ductile metallic matrices with the high strength of reinforcements, such as SiC, Al 2 O 3 or carbon nanotubes. In the past two decades, metallic glasses have been widely studied and are considered as promising candidates for the next-generation structural materials due to their high strength, large elastic limit and high corrosion resistance 2 . Metallic glasses have been suggested as an alternative reinforcement for metal matrix composites that can significantly enhance the mechanical strength while retaining desirable plastic strain before fracture [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] . The metallic nature of the reinforcing phase plays an important role in achieving good bonding between the matrix and the glassy reinforcement and overcoming many of the usual shortcomings of the conventional ceramic reinforcing phases, such as interfacial reactions, agglomeration of particles and porosity 5,18 . However, up to date, the amorphous/crystalline interfaces in MMCs have not been well studied at the atomic scale. Such studies would be of great fundamental interest and vital importance for advanced structural applications. The nature of the interface plays a significant role determining the mechanical behavior and deformation mechanisms of composite materials. For example, poor adhesion, pores or the formation of brittle intermetallic phases at the interf...

Formation of Nanoscale Metallic Glassy Particle Reinforced Al-Based Composite Powders by High-Energy Milling

“…Moreover, the Al peaks were broadened, and their intensities gradually decreased with the increased milling time, indicating a gradual reduction in the crystallite size, as well as an increase in the lattice strain, which is in accordance with the typical results of milling aluminum and aluminum alloys [34]. The precipitates (MgZn 2 ) in the Al7075 alloy matrix were dissolved with milling, which can also be found in our previous work on Zr-based metallic glass fiber-reinforced AMMCs [1]. The amorphous nature of the glassy phase in composite powders can also be verified by the DSC results (shown in Figure 5).…”

“…Good bonding between the metallic glass (MG) reinforcements and metal matrices have been observed [1,[21][22][23]. For example, a 5 nm thickness interdifussion interface layer exists in the Zr-based MG short fiber reinforced Al7075 alloy, and no detrimental intermetallic compounds formed, which is helpful for avoiding crack origination near the interface, and hence improving strength and ductility [1].…”

“…Al-based metal matrix composites (AMMCs) have low density, high specific strength, and high specific stiffness [1][2][3][4][5]; thus, they have been considered preferentially as an ideal engineering material for lightweight applications in the aerospace, defense and automotive industries [6,7]. However, AMMCs usually show high strength, but limited ductility, due to the defects that exist in the AMMCs, where cracks and premature failure occur [8].…”

Synthesis and Characterization of Copper-Based Composites Reinforced by CuZrAlNiTi Amorphous Particles with Enhanced Mechanical Properties

“…When the stress reaches point 1, the soft Cu matrix begins deforming plastically, and part of the load is transferred to the amorphous particles. The stress grows at the interfaces between the matrix and particles, resulting in micro-cracks as reported in [24]. At point 2, the micro-cracks originate from the Cu matrix and propagate inside the sample.…”

Structure and Thermal Properties of an Al-Based Metallic Glass-Polymer Composite

“…Al-based metal glasses are good choices for this purpose. For example, Wang et al presented Al-based matrix composites, reinforced with different fillers, with good mechanical properties [14][15][16][17][18]. The twist extrusion technique was used for processing polymers with metallic glass, and the mechanical properties of aluminum based alloys were improved [19].…”