Research Projects

The paradigm shift in geo-political scenario, diminishing of conventional energy resources, and increasing environmental concerns has incentivized design and development of high-strength lightweight materials for structural applications. In recent times, a lot impetus has been given towards design and development of high strength Al alloys and composites for automobile applications, which in turn will help in reducing the carbon emission. The properties of the Al-based alloys can be tailored by addition of second phase reinforcements. Al matrix composites (AMCs) are usually reinforced with ceramic particulates often resulting in catastrophic failure during operation due to formation of cracks at the interfaces. The metal-ceramic bonding at the interfaces plays a major role for such catastrophic failure. For overcoming these limitations, researchers have envisaged the idea of using unconventional reinforcement like CNTs, metallic glasses, quasicrystals (QC), high entropy alloys etc. In recent times, many efforts has been made towards design and development of AMCs reinforced with Al-based quasicrystals due to cost effectiveness as well as enticing properties. These quasicrystals (QCs) are a special class of aperiodic intermetallics exhibiting enticing mechanical and functional properties. These AMCs reinforced with QCs have strength ductility trade-off at room temperature as well as elevated temperatures. It is being observed that QC reinforcement leads to the composite materials with compressive strengths exceeding that of pure Al by a factor of 2-2.5, while retaining the appreciable fracture strain. During sintering of Al-QC composites, a few crystalline/ approximant phases related to QCs were formed at the interfaces. The QC phase was found to be stable up to 623 K, while above 873 K the QC particles transformed to ω-Al7Cu2Fe phase. The high strength in the Al-QC composites may be attributed to interfacial strengthening. However, the interfaces of crystalline and the quasicrystalline lattice require extensive characterization and modelling and the same has remained unexplored. The quasicrystalline-crystalline interface may be reactive or non-reactive in nature. Further, precipitation of other intermetallic phases may change the chemistry and the state of stress at the interface, which will have a strong influence on the mechanical properties. The present proposal envisages tailoring the interfaces in Al-QC composites by high pressure spark plasma sintering followed by its detailed understanding of structure-property correlation. Therefore, it is worth studying the structure, distribution of chemical elements and evolution of any metastable phases across region of crystal-quasicrystal interfaces. Detailed characteristics of the interfaces and its mechanistic role in the determination of the deformation process of the material is likely to pave the way forward for property optimization and new kind of composite materials.