We work on novel alloys for high temperature structural applications in the aerospace, defense and transportation, nuclear energy sectors. These alloys typically include Ni-based superalloys, Ti-alloys, steels, Al-alloys, refractory metal based alloys.  Such alloys are primarily two phase with a metallic solid solution and an intermetallic phase aggregate.

We deal with various aspects of such  metallic alloys that include

1. design and assessment of novel metallic alloys beyond the conventional ones 

2. fabrication through various routes such as casting or powder based processes

3. structural stability

4. phase transformation

5. mechanical property (room and elevated temperature)

6. oxidation resistance

With increasing demands placed on environmentally, low-cost, low waste processes, advanced manufacturing processes using metallic powders are being sought for high value-added engineering components. Such processes could be carried out with or without the use of lasers and applicable within a wide range of structural engineering sectors including transportation (aerospace, automotive, locomotive, marine), defense, biomedical industries either for large scale manufacturing or repair processes. 

A few examples of such processes  include

Manufacturing - Selected Laser Melting, Direct Laser Deposition

Repair - Cold spray, Thermal spray, Localized heat treatment

While manufacturing processes are focused on fabrication of bulk components with complex geometries, repair processes are meant to refurbish damaged structural components, especially high-value ones, using powder based processes for reintroduction to regular operation. Given the unique thermal cycles and  mass transfers associated with such processes, the  microstructures of  even conventional metallic alloys differ drastically from those in their cast or wrought counterparts 

In LAMMP,  we are interested in studying, firstly, the microstructural response (phase equilibria and distribution) of metallic alloys and composites fabricated by such advanced processes and secondly, the properties of fabricated parts.  

A wide range of technologies exist that modify the surface properties of metallic alloy components for rendering certain unique functionalities. Most often these processes produce residual stresses in the subsurface region that could be used to our advantage in terms of improving fatigue, fracture resistance and oxidative properties at high temperatures.

Some of the processes (not exhaustive) which are of interest in our group include laser-peening, shot-peening, solid-state cold spraying, localised induction heating, deep cold rolling and brazing.

We are interested in how the mechanical properties of metallic surfaces improves through these treatments and characterizing the defect microstructure and the interaction of defects with the constituent phases.

High temperature intermetallic based alloys comprise of complex intermetallic phases. Such phases generally have distinct atomic position in their crystal structure with possibilities of even anti-site substitution or vacancy, which adds to the structural complexity and also renders unique properties to the phase and thereby the alloy. In two phase alloys, compatibility of two phases or in other words, crystallographic registry is of great importance for a better phase compatibility and structural stability of the alloys. 

We use complementary experimental tools such as diffraction-based (x-ray, neutron/synchrotron) and microscopy (transmission electron microscopy) with theoretical structural models to characterize and understand the phase and interface crystallography in materials