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In the present study, Cu-1, 2 and 3 wt.% xGnP composites have been developed by powder metallurgy (PM) route using nanostructured Cu powder and their effect on microstructure, microhardness, sliding wear behaviour has been examined. The crystallite size and lattice strain of Cu after 25 h of mechanical milling have been found to be 16 nm and 0.576%, respectively. Major challenges associated with the development of Cu-xGnP composites is the uniform dispersion of the nanoplatelets in the Cu matrix, which have been dealt out by incorporating the nanostructured Cu- xGnP composites after mechanical alloying leading to the homogenous distribution of nanoplatelets in the Cu-matrix. A significant enhancement in relative density, microhardness and wear resistance of the Cu-3 wt. % xGnP nanofiller composite in particular has been observed due to the uniform distribution of the nanofillers. In Cu-3 wt. % xGnP composite developed using as-milled nanostructured Cu, a microhardness of ∼ 1.1 GPa could be achieved which is about ∼3 times higher than that of the pure sintered Cu sample (∼359 MPa). Nanostructured Cu also leads to enhancement of the hardness and wear property as compared to the as-received Cu. The wear mechanism in the various nanostructured Cu-xGnP composites has been studied in details.

In the present investigation, Cu-multiwalled carbon nanotubes (MWCNTs) nanocomposites were developed through mechanical milling using nanostructured Cu as a matrix and MWCNTs as nanofillers. The influence of nanostructured Cu on the microstructure, microhardness, and wear behavior of Cu-MWCNTs nanocomposites was also studied. The crystallite size of nanostructured Cu powder via mechanical milling for 25 h was found to be 16 nm. The major challenge associated with the development of Cu-MWCNTs nanocomposites is the uniform dispersion of the CNTs in the Cu matrix, which was addressed by incorporating nanostructured Cu, leading to the homogeneous distribution of CNTs and good bonding between the CNTs and the Cu matrix. A significant improvement in relative density and microhardness with

In the present work, Al-based metal matrix composites (MMCs) have been developed by the powder metallurgy (PM) route using exfoliated graphite nanoplatelets (xGnP) as nanofillers and their microstructure, microhardness and sliding wear behaviour were investigated. The Al-based MMCs were developed by using nanostructured Al powder developed by mechanical milling for 25 h in a high energy planetary ball mill. The crystallite size and lattice strain of Al after 25 h of milling were found to be 32 nm and 0.383 %, respectively. Al-1, 2, 3 wt.% xGnP composites were developed by the PM route. A significant improvement in both the microhardness and wear resistance of the Al–xGnP up to addition of 3 wt.% of the nanofiller was observed. For Al-3 wt.% xGnP composite developed using as-milled nanostructured Al, a microhardness of ∼ 1 GPa could be achieved, which is ∼6 times higher than that of the pure sintered Al sample (∼ 169.7 MPa). Nanostructured Al also leads to enhancement of the wear behaviour as compared to as-received Al. The wear mechanism in the various composites was found to involve a combination of abrasion, ploughing, delamination, microcracks, deep grooves and pullout of nanofillers.

Effect of stacking fault energy (SFE) on microstructural and crystallographic aspect of high-velocity deformation of FCC metals (Ni, Cu, and austenitic stainless steel) via blast assisted deformation have been investigated in this work. Microstructural changes have been probed via XRD line profile analysis and electron back-scattered diffraction methods along with TEM analysis for selected samples. The texture of all deformed material tends towards a developed α-fiber, which is observed to be strain-dependent. The relative fraction of Brass to Goss texture components increases with a decrease in SFE. The annealing twin boundaries, present in the initial material, transform in segments or full to high angle random boundary in all the material due to the dislocation pile-up. However, the microstructure of the deformed material depends heavily on the SFE, with nickel showing dislocation cells, and, austenitic stainless steel (ASS) has a mix of features of homogeneous dislocation, deformation bands, and deformation twins. Relatively thick deformation twins form in grains having orientations other than {110} plane normal to the blast direction. The overall microstructure of ASS gives an impression of a superimposed microstructure. Such structure is expected to be a result of shock passage through the material followed by macroscopic straining. No such superimposed microstructure has been observed in nickel which is attributed to recovery behavior prevalent in high SFE materials.

The present study deals with the hot deformation behaviour of as-cast Mg alloys AM30 and AM50. The alloys have been investigated for mechanical and microstructural evolution in the temperature range 423–623 K and strain rate range of 10−3–10 s−1. A safe processing domain is identified for as-cast AM30 and AM50 alloys from the strain rate sensitivity map. The deformed microstructure of both AM30 and AM50 alloy reveals the occurrence of dynamic recovery and recrystallization for temperature above 523 K. Although the two alloys show similar behaviour in the hot deformation regime, they deviate at 623 K and low strain rate, where AM30 is fully recrystallized while AM50 attains necklace structure after deformation. This is likely due to the difference in the rate of dynamic recovery in the two alloys owing to the difference in Al concentration. Continuous dynamic recrystallization was the recrystallization mechanism active in the processing regime as deduced from the EBSD investigation.

Inconel 718 is a precipitation-strengthened Ni-based superalloy which finds applications across a wide temperature range (up to 650°C). It shows excellent yield strength, ductility, creep resistance and fatigue strength. Surface treatment is known to improve the fatigue life of materials via nano-crystallization of the surface layer. However, the precipitation behavior of the surface-treated layer is largely unexplored. In this regard, the present study aims to investigate and compare the precipitation in the surface-treated layer and the bulk solution-treated IN718. The material is subjected to surface mechanical attrition treatment (SMAT) after solution treatment and is followed by a two-step aging treatment which promotes the precipitation of γ″/γ′ in the alloy. The precipitation behavior shown by the bulk and SMAT layer was different. After aging, the bulk shows a microcrystalline γ matrix containing γ″ precipitates, whereas the microstructure of the surface layer consists of nanograins with nanotwins. No evidence of γ″/γ′ precipitates were observed in the SMAT layer. The formation of nanograins in the surface layer after aging is attributed to recrystallization with controlled grain growth. The differential microstructures due to the chosen processing route have resulted in increased hardness of the surface layer and increased wear life of the material.

The grain boundary engineering (GBE) approach was employed on a medium manganese (Mn) based twinning induced plasticity (TWIP) steel to improve its mechanical properties. Two specially designed thermo-mechanical processing (TMP) routes, one involving unidirectional rolling (UDR) and the other one employing multi-step cross rolling (MSCR), with intermediate short term annealing treatment have been used. The annealing temperatures are chosen considering recrystallization and grain growth. Of the two routes, the one involving MSCR, has shown a higher fraction of special or coincident lattice site (CSL) grain boundaries. A detailed grain boundary microstructural analysis has been carried out by electron backscatter diffraction (EBSD) for differently processed samples. A significant improvement in ductility is observed in MSCR processed samples due to increase of CSL boundary fraction.

Cu-based composites reinforced by MWCNTs were developed by PM route and their microstructure, mechanical properties, sliding wear behaviour and crystallographic texture was investigated. The MWCNTs were synthesized by LPCVD technique and was functionalized using acid modification route. Cu-1, 2 and 3 wt. % MWCNT composites were developed by blending the Cu and MWCNTs powders which were later consolidated under a uniaxial load of 565 MPa and sintered at 850°C for 2 h in Ar atmosphere. A significant improvement in relative density, microhardness and wear resistance of the composites was observed up to the addition of 2 wt. % of MWCNTs.

In the present work, nanostructured $$\hbox {Fe}_{3}\hbox {Al}$$ intermetallic compound has been synthesized by mechanical alloying (MA) of $$\hbox {Fe}_{75}\hbox {Al}_{25}$$ powder milled for 40 h followed by heat treatment at $$1100\,{^{\circ}}\hbox {C}$$ for 2 h in Ar atmosphere. The structural evolution of the $$\hbox {Fe}_{75}\hbox {Al}_{25}$$ powder during MA and subsequent isothermal annealing was analyzed using X-ray diffraction (XRD). After 40 h of milling, a disordered Fe(Al) solid solution is formed. On annealing, the Fe(Al) solid solution undergoes an ordering transformation resulting in the formation of ordered $$\hbox {D0}_{3}$$ - $$\hbox {Fe}_{3}\hbox {Al}$$ . The presence of the (111) superlattice peak in the XRD plot of the annealed powder is a direct evidence of the ordered arrangements in the alloy. A shallow exothermic peak below $$600\,{^{\circ}}\hbox {C}$$ in the DSC plot of the 40-h milled powder also confirms the formation of ordered $$\hbox {D0}_{3}$$ - $$\hbox {Fe}_{3}\hbox {Al}$$ . The EDX analysis of the $$\hbox {Fe}_{75}\hbox {Al}_{25}$$ powder milled for various periods of time confirmed the gradual increase in Al diffusion in the Fe particles. The diffusion process of Al in Fe was analyzed using the elemental maps of Fe and Al in the $$\hbox {Fe}_{75}\hbox {Al}_{25}$$ powder milled for various periods of time. HRTEM images confirmed that the $$\hbox {Fe}_{3}\hbox {Al}$$ synthesized by MA is

Magnetic nanoparticles of cobalt ferrite are synthesized via a simple reduction route. These synthesized nanoparticles were characterized using x-ray diffraction (XRD), Scanning Electron Microscopy, Raman Spectroscopy, Fourier Transform Infrared studies and their magnetic properties were measured using Vibrating-sample magnetometer. The XRD analysis confirms the formation of single phase CoFe2O4 nanoparticles, with cubic spinel structure, having crystalline size of 5-10 nm, depending on the annealing temperature. Raman spectra analysis confirmed that all the synthesized powders are phase pure. The maximum magnetic saturation of 268 A m(-1) has been observed for the sample calcined at 600 degrees C and correspondingly the magnetic anisotropic constant values are reported. The proposed hydrazine reduction synthesis route is simple in execution and cost effective, which makes it economically adaptable for large scale production of CoFe2O4 nanoparticles.

In the present investigation, aluminum-based nanocomposites using multiwalled carbon nanotubes (Al-MWCNTs) were developed using nanostructured Al as a matrix and MWCNTs as nanofillers through a powder metallurgy route. The effect of nanostructured Al on the microstructure, microhardness, and sliding wear behavior of Al-MWCNT composites was studied. The crystallite size of nanostructured Al via mechanical milling for 25 h was found to be 32 nm. The major challenge associated with the development of Al-MWCNT nanocomposites is the uniform dispersion of the CNTs in the Al matrix, which was addressed by incorporating nanostructured Al. A significant improvement in the relative density, microhardness, and wear resistance of the Al-MWCNT composites up to the addition of 2 wt% of the MWCNTs was observed compared with as-received Al and its composites. The hardness of an Al-2 wt% MWCNT composite developed using nanostructured Al was 800 MPa, which was five times higher than as-received Al (170 MPa). Hardness and wear resistance found to be inversely proportional to crystallite size and porosity. The significant incremental improvement in the mechanical and wear properties mainly originates from fine-grain strengthening effects and the homogenous distribution of MWCNTs in the Al matrix. The presence of well-dispersed CNTs while maintaining structural integrity and aluminum carbide (Al4C3) crystals in the Al matrix were observed. The wear mechanism of Al-MWCNT nanocomposites was studied in detail. The wear mechanism of nanostructured Al composites has not been discussed in the literature previously; thus, this is the first comparative study of micro-and nanostructured Al-based composites.

Over the span of years, improvements over various synthesis methods of graphene are constantly pursued to provide safer and more effective alternatives. Though the extraction of graphene through Hummers method is one of the oldest techniques yet it is one of the most suitable methods for the formation of bulk graphene. Graphene can be obtained in the form of reduced Graphite oxide, sometimes also referred as Graphene oxide. The effectiveness of this oxidation process can be evaluated by the magnitude of carbon/oxygen ratio of the obtained graphene. Here, graphene oxide (GO) was prepared by oxidizing the purified natural flake graphite (NFG) by a modified Hummers method. The attempts have been made to synthesize GO having few layers by using a modified Hummers method where the amount of NaNO3 has been decreased, and the amount of KMnO4 is increased. The reaction has been performed in a 9:1 (by volume) mixture of H2SO4/H3PO4. This modification is successful in increasing the reaction yield and reducing the toxic gas evolution while using a varied proportion of KMnO4 and H2SO4 as those required by Hummers method. A new component of K2S2O8 has been introduced to the reaction system to maintain the pH value. Reduced graphene oxide (rGO) was thereafter extracted by thermal modification of GO. Here, GO has been used as a precursor for graphene synthesis by thermal reduction processes. The results of FTIR and Raman spectroscopy analysis show that the NFG when oxidized by strong oxidants like KMnO4 and NaNO3, introduced oxygen atoms into the graphite layers and formed bonds like C=O, C-H, COOH and C-O-C with the carbon atoms in the graphite layers. The structure and morphology of both GO and rGO were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy, Raman spectroscopy, Brunauer-Emmett-Teller (BET) surface area analysis and differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA).

NanostructuredInt. J. Mod. Phys. Conf. Ser. 2012by 14.139.208..Int. J. Mod. Phys. Conf. Ser. 2012by 14.139.208.. TiB 2 powder was synthesized by mechanical alloying (MA) of Ti and B powders in the proper stoichiometric ratio for 60 h in a high energy planetary ball mill followed by heat treatment at 900 o C for 1 h in Ar atmosphere. The structural evolution of the powder during ball milling was analyzed using XRD, SEM, and HRTEM. The Zn-TiB 2 nanocomposites fabricated by powder metallurgy route shows an increase in hardness as well as wear resistance with the increase in the content of TiB 2 .

Aluminum (Al)-based metal matrix composites reinforced with multiwalled carbon nanotubes were developed by powder metallurgy route. The Al and multiwalled carbon nanotubes powder mixtures were consolidated under a load of 565 MPa followed by sintering at 550℃ for 2 h in inert atmosphere. Al–1, 2, and 3 wt.% multiwalled carbon nanotube composites were developed. In the present study, the microstructure, mechanical properties, sliding wear behavior, and crystallographic texture of various Al–multiwalled carbon nanotube composites were investigated. The multiwalled carbon nanotubes produced by low-pressure chemical vapor deposition technique and the various sintered composites were characterized using scanning electron microscope, high-resolution transmission electron microscope, X-ray diffraction, differential scanning calorimetry and thermogravimetric analysis, Raman spectroscopy, and Fourier transform infrared spectroscopy. A significant improvement in relative density, Vickers microhardness, and wear resistance of the composites up to addition of 2 wt.% of multiwalled carbon nanotubes was observed. The deterioration in these properties beyond 2 wt.% of multiwalled carbon nanotubes was possibly due to the agglomeration of multiwalled carbon nanotubes in the Al matrix. The tensile strength of Al–multiwalled carbon nanotube composites continuously decreases with the addition of multiwalled carbon nanotubes. The decrease in tensile strength can be attributed to the detrimental effect of Al4C3 formed at the interface of the Al matrix and the multiwalled carbon nanotubes which will cause premature failure of the composite. The addition of multiwalled carbon nanotubes altered the crystallographic texture of the composites. The residual stresses in the various composites were found to be compressive in nature and also show improvement up to addition of 2 wt.% multiwalled carbon nanotubes in the Al matrix.

In this work Al-matrix composites reinforced by exfoliated graphite nanoplatelets (xGnP) is fabricated by powder metallurgy route and their microstructure, mechanical properties and sliding wear behaviour were investigated. Here, xGnP has been synthesized from the thermally exfoliated graphite produced from a graphite intercalation compound (GIC) through rapid evaporation of the intercalant at an elevated temperature. The xGnP synthesized was characterized using scanning electron microscope (SEM), high-resolution transmission electron microscope (HRTEM), x-ray diffraction (XRD), atomic force microscopy (AFM), x-ray photoelectron spectroscopy (XPS), differential scanning calorimetry and thermogravimetric analysis (DSC/TGA), Raman spectroscopy and Fourier transform infrared spectroscopy (FTIR). The Al and xGnP powder mixtures were consolidated under a load of 565 MPa followed by sintering at 550 °C for 2 h in an inert atmosphere. Al-1, 2, 3 and 5 wt% xGnP nanocomposites were developed. Results of the wear test show that there was a significant improvement in the wear resistance of the composites up to the addition of 3 wt% of xGnP in the Al matrix. The hardness of the various Al-xGnP composites also shows improvement upto the addition of 1 wt% xGnP beyond which there was a decrease in the hardness of the composites. The tensile strength of the Al-xGnP composites continuously reduced with the addition of xGnP due to the formation of Al4C3 particles at the interface of the Al and xGnP in the composite.

In the present investigation, Cu-based MMCs have been developed by PM route using exfoliated graphite nanoplatelets (xGnP) and MWCNTs as nanofillers and their influence on mechanical properties as well as crystallographic texture have been studied. xGnP possesses fine particle size as well as less disorder as compared to MWCNTs. Relative density, hardness and wear resistance found to be increased with the addition of nanofillers upto 2 wt% xGnP/MWCNTs, whereas porosity found to decrease with the addition of nanofillers upto 2 wt%. The hardness of Cu-2 wt% xGnP composite was found to be 560 MPa, which is about 1.6 times higher than that of the pure Cu sample (350 MPa) and 1.2 times greater than Cu-2 wt% MWCNTs composite (475 MPa). The wear mechanism was found to involve a combination of abrasion, ploughing, delamination, microcracks, deep grooves and pullout of nanofillers in all the composites. The tensile strength of the various Cu-xGnP composites shows an improvement upto the addition of 2 wt% xGnP. The maximum tensile strength of 130 MPa was achieved in the case of Cu-2 wt% xGnP composite, which is about 1.7 times higher than that of the pure sintered Cu sample (76 MPa). However, the tensile strength of the various Cu-MWCNT composites continuously decreases with the addition of MWCNTs. The homogenous distribution of xGnP, as well as good bonding of xGnP with Cu matrix, has been observed in SEM and TEM images of composites, which is found to be more dominant as compared to MWCNTs distribution in Cu-matrix. The residual stress in the various composites was found to be compressive in nature, and it shows a similar trend as that of the other properties like hardness and wear behaviour of the composites. The addition of nanofillers also altered the crystallographic texture of the composites. xGnP leads to weaker texture as well as decrees in the volume fraction of 〈0 1 1〉 fiber as compared to MWCNTs in Cu-based MMCs, which leads to having superior mechanical properties as compared to MWCNTs composites.

This study investigates the exact state of deformation in single point incremental forming (SPIF) and double-sided incremental forming (DSIF) techniques using experimental observations of texture evolution coupled with a multiscale simulation of the processes. The texture evolution was investigated for different sets of forming parameters such as vertical displacement, wall angle and tool diameter. It was observed that difference in crystallographic texture due to change in tool diameter and vertical displacement was marginal. However, significant difference in texture evolution was observed upon changing the wall angle. Further analysis of crystallographic texture revealed that role of through thickness shear (TTS) is limited in case of DSIF process compared to SPIF process. Numerical simulation of SPIF process via finite element method was successful in capturing the contribution from TTS in SPIF process. Based on insights obtained from finite element calculations, Visco-Plastic Self-Consistent simulations were carried out which were successful in predicting the experimental texture. Finally, the effect of different incremental forming techniques on the mechanical properties of the formed components was studied. The observed anisotropy in yield strength was explained based on the inverse of average Schmid factor. Lankford parameter and yield locus were also estimated from the experimental textures to understand the feasibility of incremental forming at different wall angles.

The present work investigates the microstructure, sliding wear resistance and hardness of an aluminium MMC reinforced with different (10,20,30) vol. % of Fe 3 Al intermetallic developed by powder metallurgy route. Nanocrystalline Al developed by ball milling was mixed with Fe 3 Al in different vol. % and compacted under uniaxial load of 222 MPa and sintered at 500 o C in Aratmosphere. Wear tests of the various Al-Fe 3 Al composites showed that the wear resistance of the Al-Fe 3 Al composites improved significantly with the increase in vol. % of Fe 3 Al. The hardness of the compositesalso showed increase with the increasing vol. % of Fe 3 Al.

In the present investigation the possibility of using exfoliated graphite nanoplatelets (xGnP) as reinforcement in order to enhance the mechanical properties of Cu-based metal matrix composites is explored. Cu-based metal matrix composites reinforced with different amounts of xGnP were fabricated by powder metallurgy route. The microstructure, sliding wear behaviour and mechanical properties of the Cu-xGnP composites were investigated. xGnP has been synthesized from the graphite intercalation compounds (GIC) through rapid evaporation of the intercalant at an elevated temperature. The thermally exfoliated graphite was later sonicated for a period of 5 h in acetone in order to achieve further exfoliation. The xGnP synthesized was characterized using SEM, HRTEM, X-ray diffraction, Raman spectroscopy and Fourier transform infrared spectroscopy. The Cu and xGnP powder mixtures were consolidated under a load of 565 MPa followed by sintering at 850°C for 2 h in inert atmosphere. Cu-1, 2, 3 and 5 wt% xGnP composites were developed. Results of the wear test show that there is a significant improvement in the wear resistance of the composites up to addition of 2 wt% of xGnP. Hardness, tensile strength and strain at failure of the various Cu-xGnP composites also show improvement upto the addition of 2 wt% xGnP beyond which there is a decrease in these properties. The density of the composites decreases with the addition of higher wt% of xGnP although addition of higher wt% of xGnP leads to higher sinterability and densification of the composites, resulting in higher relative density values. The nature of fracture in the pure Cu as well as the various Cu-xGnP composites was found to be ductile. Nanoplatelets of graphite were found firmly embedded in the Cu matrix in case of Cu-xGnP composites containing low wt% of xGnP.

Cu-E glass fiber composites were developed with different vol. % of E-glass fiber (10, 20, 30 and 40 vol. %) by powder metallurgy route. Both as-received Cu and nanostructured Cu developed by milling as-received Cu powder for 20 h were used to develop various Cu-E-glass fiber composites. The effect of using as-received Cu powder and nanostructured Cu powder on the properties of the various Cu-E-glass fiber composites was analysed. The samples were sintered at 900oC for 1 h in inert atmosphere. The results show good bonding between the matrix and the reinforcement and there is homogeneous distribution of the reinforcement in the matrix.. The hardness of the Cu-E-glass fiber composites was found to increase from 0.8GPa to 2.7GPa with increase in vol. % of the glass fiber in case of unmilled and from 1.2GPa to 2.9GPa for the milled Cu-E-glass fiber composites. The as-milled Cu-E- glass fiber composites shows better densification and sinterability compared to the unmilled CuE-glass fiber composites

This paper presents the results of Cu-SiCp composites developed by powder metallurgy route and an attempt has been made to make a comparison between the composites developed by using unmilled Cu powder and milled Cu powder. SiC particles as reinforcement was blended with unmilled and as-milled Cu powderwith reinforcement contents of 10, 20, 30, 40 vol. % by powder metallurgy route. The mechanical properties of pure Cu and the composites developed were studied after sintering at 900°C for 1 h. Density of the sintered composites were found out based on the Archimedes' principle. X-ray diffraction of all the composites was done in order to determine the various phases in the composites. Scanning electron microscopy (SEM) and EDS (electron diffraction x-ray spectroscopy) was carried out for the microstructural analysis of the composites. Vickers microhardness tester was used to find out the hardness of the samples. Wear properties of the developed composites were also studied.