Developing a new series of Al-based simple ternary Al-Cu-TM/Al-TM-Si alloys (TM = early transition metals = Ti, Nb, Zr) by mechanical alloying amenable to forming an amorphous phase dispersion in nanocrystalline matrix, or nano-intermetallic dispersion in amorphous or nanocrystalline matrix either during controlled milling or subsequent annealing [5,21,25,28,32-35,43-44,46,52,55,60,63,126,139,145,146,169,170]. A patent has recently been granted on one such system (Al-Cu-Ti) [P-2].

Discovering bcc->fcc (in Nb) and hcp->fcc (in Zr, Ti) polymorphic transformation in early transition metals during mechanical attrition due to nanocrystallization and high degree plastic strain/strain-rate. Also, proposing a thermodynamic model based on isothermal equation of state to explain the genesis of such transformation upon nanocrystallization and proving that the said transformation is not impurity driven [18,19,36,49,51,53,64,66,68]. Similar transformation has since been report in other systems including ceramic and metallic alloys.

Developing nanometric metallic (Al-alloy) or ceramic (zirconia/titania) dispersed (< 2 vol.%) water/ethylene glycol based nanofluid recoding 50-150% increase in thermal conductivity ratio with less than 2 vol.% nano-particles for advanced heat transfer applications [1,16,26,167,173].

Synthesizing nanocrystalline superparamagnetic (Hc < 1 Oe) Mn-Zn spinel-ferrites [8,20,128].

Proposing a numerical model of mechanical alloying kinetics capable of considering the concentration dependent diffusivity, interface shift, and introducing the idea of an effective temperature of diffusion in mechanical alloying for the first time [75,91].

Correlating the excess free volume or volume per atom in nanocrystals with grain size [66] and accounting for the "inverse Hall-Petch" relation [71] and "enhanced diffusivity" [67] in terms of negative hydrostatic pressure generated due to nanocrystallization (crystallite size reduction beyond a critical level). The same concept was successfully applied to explain polymorphic changes in early transition metals due to nanocrystrallization.

Proposing a mathematical model of milling dynamics to predict the optimum conditions of mechanical alloying to develop nanocrystalline alloys [65].

Developing several nanocrystalline aluminide (Nb-Al, Cu-Al, Ni-Al) at room temperature with metastable microstructure or composition from elemental powder blend by mechanical alloying [87,95].

Improving oxidation and wear resistance of Ti by laser surface alloying (LSA) with Si, Al or Si+Al forming a Ti5Si3-rich layer and understanding the concerned mechanism of oxidation and wear resistance due to Ti5Si3-rich layer [57,73,82,89,155,175].

Developing a new strategy of laser assisted composite surfacing (LCS) to significantly enhance resistance to wear in Al/Al-alloys [4,12,13,130,132,134], Cu/Cu-alloys [9,15,129], Mg-alloys [10,39,50,143] and stainless steel [23,24].

Enhancing wear and erosion (both at room/high temperature) resistance of Cu by LSA with Cr by solid solution and dispersion hardening. A process map concerning laser parameters and surface microstructure, composition and hardness has been established [81,83,99,105,107,160].

Improving corrosion and wear resistance of Mg-alloys by laser surface melting (LSM) or LSA with Al+Mn [40,48,56,137,140-144,147].

Enhancing oxidation resistance of 2.25Cr-1Mo ferritic stainless steel by LSA with Cr [149] and pitting and general corrosion resistance and wear resistance of AISI 304/316 austenitic stainless steel [80,101,156] by LSA with Mo.

Developing high specific surface area neural stimulation electrode by LSA of Ti with Ir and mimic the spatio-temporal profile of neuronal activation to cure neuronal disorders (like tinnitus, cardio-vascular stimulation, etc.) [92,150,159,161].

Demonstrating for the first time that laser surface hardening is more appropriate for enhancing wear and fatigue resistance of austempered ductile iron than that by LSA or laser surface melting due to a residual compressive stress on the surface [69,70,152,154].

Developing a co-deposition technique to apply nano-aluminides on surfaces of copper to enhance wear resistance without deteriorating electrical conductivity. This is the first time that co-deposition of nano-aluminide/intermetallic has been possible [62,74].

Laser assisted bending of stainless steel (for automobiles) [38,41] and laser assisted fabrication of stainless steel [29-31,127,131,133].

Laser surface hardening (LSH) of plain carbon and ball bearing steel [2,138,151].

Exploring laser assisted fabrication/deposition of bio-implants using metallic powders [11,22].

Reviewing different aspects of LSE [14,45,94,111,148,174].

Enhancing wear and corrosion resistance of ball bearing steel by different surface engineering approaches (gas and plasma nitriding, plasma ion implantation) [2,3,59,171,168]

Earlier Prof. Manna developed a novel technique of enhancing diffusion coating kinetics by increasing specific boundary area on surface through controlled surface deformation and diffusion annealing [112].

Utilizing plasma ion implantation based surface engineering to enhance hardness and corrosion resistance of stainless and ball bearing steel [7,27,37,42,47,58,59,135,168]. Prof. Manna installed a plasma-immersion-ion-implantation (PIII) facility in 2000 with a DST project, which has now been upgraded to an indigenously designed/developed plasma assisted implantation and deposition (PAID) unit (a new hybrid deposition and implantation technology) through another DST funding. This is the first university based PIII/PAID laboratory in India (for metallic/ceramic components).

Discovering DP/DC in several new binary systems: Cd-Ag [97], Zn-Al [113,118], Zn-Ag [76,98,110], Zn-Cu [103].

Establishing that the dynamic properties (diffusivity, mobility, etc.) of the grain vis--vis interphase boundaries are comparable in moving boundary reactions [61,114,115,123] and suggesting that grain boundaries undergo no structural transformation to attain mobility from static condition in moving boundary reaction (hence static/dynamic boundaries have same structure) [114,115,122]. In this regard, a generalized criterion for selection of the initiation sites for DP and DC from among different types of natural and/or synthetic grain and phase boundaries was proposed [109,115,119,120]. Indeed, it was shown that initiation of DP is feasible from interphase boundaries that allowed formulating a new mechanism of DP initiation from interphase boundaries for the first time [114,115,119].

Proving that Livingston-Cahn orientation relationship between the lamellae of the primary and secondary colonies is not mandatory for initiation of DC from DP [76,90,93,98].

Innovating a new resistometric method of determining metastable solvus for DP [121], and discovering a clustering reaction (volume diffusion controlled) preceding DP in Pb-Sn [124] for the first time.

Developing a novel technique of determining the Arrhenius parameters of boundary diffusion through kinetic analysis of DP and DC. Utilizing this, he has determined boundary diffusivity through kinetic analysis in many systems in which reliable data on the same were not available [61,76,93,97-98,103-104,110,114,118,162,164]. This approach is proven applicable in principle to all moving boundary reactions.

Resolving the controversy about the effect of ternary addition on DP kinetics and proving that solute drag exerted by the ternary atoms, neither atomic size difference nor valence electron difference constitutes the main mechanism of retarding the DP kinetics [116].

Reporting that volume diffusion controlled metastable decomposition (say, clustering) precedes boundary diffusion controlled eutectoid reaction in Cu-In for the first time [85,86,93].

Significantly contributing towards developing analytical/numerical models of peritectic and peritectoid transformation kinetics [72,78,79,88,93,96,158] that showed better insight into the transformation mechanism and better agreement with experimental data.

Developing a heat transfer model of LSA (under pre-deposition scheme) based on explicit finite difference technique to predict the temperature profile, thermal history and microstructure of the alloyed zone. This has been the maiden effort to model LSH [2] or LSA involving transient melting and solidification of a bi-metallic layer [54,102,163].

Modifying the Cahns equation to analytically predict the solute distribution profile in solute depleted matrix behind the reaction front in DP that shows excellent agreement with experimental data [108].

Mathematical modeling of the heat transfer process during a pin-on-disc wear-testing operation to demonstrate that accumulation of frictional heat may irreversibly degrade the microstructure [84].

Mathematically modeling of the heat transfer condition of austenitizing and austempering spheroidal graphitic iron to optimize bainitic transformation and microstructure [69,157].