Phase Transformations Group

Our main interest lies in liquid to solid and solid state phase transformations during materials processing operations. Alloy chemistry (through the associated thermodynamics and kinetics) and processing conditions influence these transformations and control the microstructural evolution of materials. An understanding of the role of individual factors and their interplay enable us to design and obtain material properties that we want for engineering applications. Although I'm primarily an experimetalist, we do complement and supplement experiments with computations involving macroscopic transport processes and microstructural aspects.

Metallurgy of welding and additive manufacturing

The goal here is to connect process variables (power, speed, energy density, linear heat input) with thermal history in the material and resulting microstructural which eventually influence the properties. In the past, we have studied dissimar welding of Ni-Ti couples (without and with an interlayer), both experimentally and using computational tools. Right now, students in the group are working on welding and/or AM of superalloys and high entropy alloys. In addition to structural and mechanical characterization, we try to connect microstructure formation to the thermodynamics and kinetics specific to these systems. We have collaborated with my colleagues in the MSME (Prof. Rajesh) and MAE departments (Profs. Suryakumar, Viswanth, Gopinath) at IITH, as well as with Dr. Dheepa Srinivasan of Pratt & Whitney Research Center on several aspects of weld and AM processing.

Thin films and nanostructures

We analyze how phase transformations are influenced by, and in turn influence the microstructural evolution in, confined geometries such as thin films and nanostructures. Using a combination of fabrication methods (physical vapor deposition and focused ion beam milling) and characteriation (SEM/S-TEM/AFM) and computational (phase field) techniques, we explore the roles of alloy chemistry, temperature, capillarity and film-substrate interaction on structural evolution in these systems. We actively collaborate with my colleagues Profs. Saswata and Shourya to looked at, for example, morphology development in binary nanoparticles and phase separation in FIB milled Ag-Cu thin films.