FOCUSED RESEARCH AREAS OF OUR GROUP

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1. Alloy design for additive manufacturing

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Additive manufacturing (AM) is a leading manufacturing technique at present for obtaining complex shapes in automotive as well as aerospace industries. Powder bed fusion (PBF) and direct energy deposition (DED) are the two important processed for carrying out 3D printing of these shapes by using different heat/energy sources such as laser, electron beam etc. However, this process being very complex and involves localized non-equilibrium melting and solidification, there are limited materials available which can be 3D printed using AM. Thus, this work mainly involved designing new materials by taking into account the fundamental requirements for AM such as absorptivity, viscosity, phase stability and thermal conductivity of the particular alloy system. The ultimate aim is to attain selected alloy compositions which can give good 3D printed component with good surface finish and minimized porosity.

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2. Design and property optimization of metastable High Entropy Alloys (HEAs)

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The cogent potential of high entropy alloys to exhibit an extraordinary combination of properties just by flipping the compositional regime and processing route has led to worldwide attention by material scientists. The proposed work here involved design of new compositions of HEAs which can break the strength-ductility tradeoff (inverse relationship) upon subsequent microstructural engineering. The main aim is to enhance the performance of the HEAs by tuning the stability of f.c.c. matrix which will inherently engineer their deformation response by incorporating phenomena such transformation or twin induced plasticity (TRIP, TWIP) along with classical dislocation assisted deformation. On top of that, the core effects in HEAs (namely high entropy, sluggish diffusion and lattice distortion would help in boosting the other physical properties (i.e. electrical conductivity, density etc.) of them. This can be achieved by the effective use of modelling tools and experimentation such that the resultant new HEA will have excellent combination of mechanical, physical and corrosion properties. At last, the maximum benefit of abundant compositional space of non-equiatomic HEAs is being explored for obtaining multifunctional HEAs which is otherwise not feasible with steel design.

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3. Friction Stir Processing and Welding of Low and High Strength Alloys 

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a. Friction stir processing (FSP) is considered as one of the industrially feasible severe deformation technique which can result in drastic improvement in mechanical performance of the material. This project attempts to do FSP of newly designed materials such as high entropy alloys, steels, and magnesium based alloys for the first time to understand their response in terms of structure-property relationship. The processing window for the successful FSP run will be set for selected materials in terms of RPM, IMP and tilt angle. The initial FSP data would be an indication of futuristic use of these materials for friction stir welding (FSW).

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b. Dissimilar Friction Stir Welding (D-FSW) is considered to be very powerful solid state welding route in joining metals which are otherwise very difficult to weld by conventional fusion welding. This project mainly attempts to weld few of the material combinations which were never welded by any of the techniques such as high strength WE43 and E765 Mg alloys with series of Al alloys such as 2XXX, 5XXX, 6XXX and 7XXX alloys in both lap and butt configurations. The joint strength would be estimated with lap shear tests and microstructural evolution in terms of formation of IMC layer will be studied in detail. Combinations such as Cu alloys and steels would also be tried since Cu-Fe is known to be immiscible system and thus would not result in the formation of IMC upon FSW.

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4. Development of ultralight and ultrafine grained Mg alloys 

This project mainly involved design of new Mg alloys containing Li and Ca as alloying elements for its application as biodegradable implant and in lightweight industry. The main reason for selecting Li and Ca as constituent elements is their low density and good biocompatibility. The detail study of phase diagrams and literature suggested that addition of Li less than 5 wt % and Ca 1 wt % is suitable in avoiding any adverse effects on the resultant microstructure. Thus a newly designed alloys will be studied for interdependence of microstructural evolution and mechanical properties under as-cast and thermo-mechanically processed conditions.

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