Metal/ceramic interface structures and segregation behavior in aluminum-based composites

Abstract

a b s t r a c tTrimodal Al alloy (AA) matrix composites consisting of ultrafine-grained (UFG) and coarse-grained (CG) Al phases and micron-sized B 4 C ceramic reinforcement particles exhibit combinations of strength and ductility that render them useful for potential applications in the aerospace, defense and automotive industries. Tailoring of microstructures with specific mechanical properties requires a detailed understanding of interfacial structures to enable strong interface bonding between ceramic reinforcement and metal matrix, and thereby allow for effective load transfer. Trimodal AA metal matrix composites typically show three characteristics that are noteworthy: nanocrystalline grains in the vicinity of the B 4 C reinforcement particles; Mg segregation at AA/B 4 C interfaces; and the presence of amorphous interfacial layers separating nanocrystalline grains from B 4 C particles. Interestingly, however, fundamental information related to the mechanisms responsible for these characteristics as well as information on local compositions and phases are absent in the current literature. In this study, we use high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy, electron energy-loss spectroscopy, and precession assisted electron diffraction to gain fundamental insight into the mechanisms that affect the characteristics of AA/B 4 C interfaces. Specifically, we determined interfacial structures, local composition and spatial distribution of the interfacial constituents. Near atomic resolution characterization revealed amorphous multilayers and a nanocrystalline region between Al phase and B 4 C reinforcement particles. The amorphous layers consist of nonstoichiometric Al x O y , while the nanocrystalline region is comprised of MgO nanograins. The experimental results are discussed in terms of the possible underlying mechanisms at AA/B 4 C interfaces.

Microstructure and Mechanical Properties of Zr–Al–Ni–Cu Metallic Glassy Particles Reinforced 7056 Al Alloy Matrix Composites Obtained by Spark Plasma Sintering

“…Otherwise, as shown in Figure f and h, both the Mg and O elements are also enriched at the interface between the matrix and glassy particles. The diffusion of Mg at the interface may improve the interfacial wettability and enhancing the interfacial bonding strength …”

Calorimetric Study with Uncertainty Analysis to Investigate the Precipitation Kinetics in a Nanostructured Al Composite

“…Previous studies on cryomilled‐plus‐consolidated bulk B 4 C‐reinforced Al–Mg alloy (Al 5083) matrix nanocomposites demonstrated that Mg segregates to the B 4 C/Al interface and forms Mg‐rich layers near the interface, as shown in Figure . A B 4 C particle located in the center of Figure a is in contact with both a coarse grained Al region at Interface 1 and ultrafine grained Al regions at Interfaces 2–4.…”

“…A variety of severe plastic deformation techniques are available to achieve grain refinement in materials, including equal channel angular pressing (ECAP), high pressure torsion (HPT), cryorolling, and ball milling . Compared to cryorolling and ECAP, which apply mechanical deformation to bulk materials to refine the grain structure, cryomilling is a powder metallurgy technique that generates nanocrystalline powder via severe plastic deformation .…”

“…a) High‐angle annular dark field scanning transmission electron microscopy image of a B 4 C/Al 5083 composite; b) Energy‐dispersive X‐ray spectroscopy illustrates the distribution of Mg …”

Bioinspired Aluminum Composite Reinforced with Soft Polymers with Enhanced Strength and Plasticity

“…Increase in strength of the material is limited to the modulus and volume fraction of stronger reinforcement . Such an approach of material design leads to stronger material, with reduced ductility due to poor interface between reinforcement and matrix . Beyond this conventional wisdom, nature has also shown examples of composite materials (e.g., intervertebral disc, etc.)…”