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In the modern era, many research works are going on throughout the world for finding suitable cementitious material for the replacement of cement since it causes environmental pollution. In this order Fly ash, Silica fume, GGBS, Metakaolin, Micro materials, Quartz powder, etc. are tried out for replacing partially or fully the cement in concrete. A new ultrafine material called Alccofine (AF) which is manufactured from glass wastes is tried out for replacing partially in this research. Compressive strength is one of the important properties of cement. Strength tests are not made on neat cement paste because of difficulties of excessive shrinkage and subsequent cracking of neat cement. Cement mortar of 1:3 mix proportion is used to cast the cubes having an area of 50 cm2 are used for the determination of compressive strength of cement as per IS: 4031-1988 (Part-6). The graded Indian Standard sand (Ennore Sand -ES) confirming to IS: 650-1991 is used for preparing the cubes. In the same mix proportion, the same size cubes are cast with the River Sand (RS) to study the difference of the compressive strength between the Indian standard sand and river sand. Ordinary Portland cement (OPC) and Portland Pozzolana Cements (PPC) are used. The present study is the influence of Alccofine on cement mortar cubes by replacing the cement by Alccofine with various proportions like 5%, 10%, 15%, 20% were cast and tested in the laboratory as per Indian Standard 4301-1988 (Part-6) and the results were analysed and presented in the form of charts and graphs. It is observed that the early age strength is obtained for all the combinations but 10 percent of Alccofine yields more strength than other dosages. Doi: 10.28991/esj-2021-01265 Full Text: PDF

The hot deformation behaviour of a Cu containing high strength low alloy (HSLA) steel has been evaluated by carrying out hot compression tests over a temperature range of 900 °C to 1100 °C and constant true strain rates of 0.0003 to 1 s−1. Although single peak flow curve is observed predominantly, a tendency to exhibit multiple peaks at low strain rates (0.0003 and/or 0.001 s−1) at temperature greater than 950 °C. The important parameters pertaining to dynamic recrystallisation (DRX), such as critical, peak, steady state stress and strain were ascertained, and the DRX state diagram depicting the variation of critical parameters governing DRX with Zener-Hollomon parameter Z was established. The volume fraction of recrystallised grains, computed from flow stress, as expected, follows a sigmoidal trend indicating higher kinetics at low strain rates for a given temperature. Reconstruction of prior austenite grain boundaries (PAGB) based on electron back scattered diffraction (EBSD) technique for a few select specimens clearly elucidated the effect of temperature and strain rate on the DRX behaviour of the steel. The DRX state diagram established here clearly demarcates the deformation space i.e. temperature-strain rate-stain space into regimes where the material exhibits full DRX, hardening/softening + DRX and only hardening (no DRX) behaviour. This would be useful for designing suitable forging sequence to achieve the desired microstructure and mechanical properties. [ABSTRACT FROM AUTHOR]

Dynamic (DRX) operative during deformation and static recrystallisation (SRX) operative after deformation are considered responsible for the changes in microstructure and texture of deformed materials. Especially in the case of advanced steels that are required in the form of plates of various thicknesses, hot rolling is the main manufacturing process during which the steel undergoes DRX under the rolls and SRX between rolling passes/strands. Knowledge on DRX and SRX characteristics of such steels is crucial for optimisation of hot rolling parameters, achieving the desired microstructure and consequently the targeted mechanical properties. In this study, certain key aspects of both dynamic (DRX) and static recrystallisation (SRX) behaviour of aCu-bearing HSLA steel, which was developed at DMRL, have been explored through high temperature deformation studies using Gleeble thermo-mechanical simulator. Through uniaxial compression testing in the austenitic regime, domains of continuous and discontinuous DRX prevalent in the steel were identified and critical parameters for initiation of dynamic recrystallisation viz., critical strain (ec), critical stress (sc), peak stress (sp) and peak strain (ep) were determined as a function of temperature and strain rate. SRX characteristics were assessed through uniaxial double hit compression tests with fixed strain rate and strain per hit but at different temperatures and with different imposed intermediate static recrystallisation (ISRT) times. From the fractional softening data, parameters such as time for 50 % recrystallisation, t0.5, temperature for 50 % recrystallisation, T0.5, and activation energy, QSRX have been estimated. Although the steel exhibited good plastic deformation characteristics, the results suggest that the role of copper in retarding recrystallisation is significant. [ABSTRACT FROM AUTHOR]

It is well established that Re and Ru additions to Ni-base superalloys result in improved creep performance and phase stability. However, the role of Re and Ru and their synergetic effects are not well understood, and the first step in understanding these effects is to design alloys with controlled microstructural parameters. A computational approach was undertaken in the present work for designing model alloys with varying levels of Re and Ru. Thermodynamic and first principles calculations were employed complimentarily to design a set of alloys with varying Re and Ru levels, but which were constrained by constant microstructural parameters, i.e., phase fractions and lattice misfit across the alloys. Three ternary/quaternary alloys of type Ni-Al-xRe-yRu were thus designed. These compositions were subsequently cast, homogenized and aged. Experimental results suggest that while the measured volume fraction matches the predicted value in the Ru containing alloy, volume fraction is significantly higher than the designed value in the Re containing alloys. This is possibly due to errors in the thermodynamic database used to predict phase fraction and composition. These errors are also reflected in the mismatch between predicted and measured values of misfit.

It had been reported that B has beneficial effects on the magnetostriction of anisotropy compensated Dy0.7Tb0.3Fe2 alloys. In the present work, Dy0.7Tb0.3Fe1.95 and Dy0.7Tb0.3Fe1.95Bx (x=0.1, 0.15, and 0.2) alloys, in the form of 8 mm diameter cylindrical rods, were investigated both in the as-cast and zoned conditions. At 5 kOe dc magnetic field, magnetostriction of ∼1200 and 900 microstrains was observed for zoned samples with x=0 and 0.1, respectively. For zoned samples with x>0.1 and for the as-cast sample of the parent alloy, magnetostriction of ∼500 microstrains was measured. X-ray diffraction of the zoned x=0 and x=0.1 samples showed a strong prevalence of the <112> and the <110> grain orientations; in contrast, the other samples appeared to possess a random grain orientation. Optical and scanning electron microscopy studies revealed a significant increase in the volume fraction of the RFe3 phase with increasing boron content. This increase in the volume fraction of the (Tb,Dy)Fe3 phase and the reduction in the desired grain orientation of the (Tb,Dy)Fe2 phase are attributed to be the reasons for the large decrease in the magnetostriction of the (Tb,Dy)Fe1.95 alloys with boron addition. [ABSTRACT FROM AUTHOR]

An intermetallic compound of nominal composition Tb0.3Dy0.7Fe1.95 was conventionally cast in the form of cylindrical rods of 8 mm diameter and directionally solidified by zoning at three different growth rates. Compounds of the same nominal composition were also directionally solidified in the form of cylindrical rods of 20 mm diameter by modified Bridgman technique, at two different growth rates. The microstructure of the directionally solidified compounds has been investigated as a function of solidification rate and compared with that of conventionally cast compound. The observed microstructural features of these samples have been correlated with the magnetostriction measured on the corresponding samples. Further, by examining the longitudinal sections cut along its cylindrical axis, a correlation of microstructure with magnetostriction has been brought out for each directionally solidified sample as a function of distance from the initially solidified end to the other. It has been observed that a large magnetostriction (at 4.5 kOe) and a high initial slope of magnetostriction versus applied magnetic field are realized in the directionally solidified samples as compared to the conventionally cast sample. An improvement in the property has been observed among the directionally solidified samples when solidified with higher growth rates. It is surmised on the basis of the observed microstructural features in this study that a large magnetostriction is realized if formation of (Tb,Dy)Fe2 occurs by congruent solidification rather than by the peritectic reaction L+(Tb,Dy)Fe3→(Tb,Dy)Fe2. [ABSTRACT FROM AUTHOR]

The alloy compositions of [Dy.sub.0.7][Tb.sub.0.3][Fe.sub.1.95] with extra addition of B are selected in order to examine the effect of zoning on the microstructure and magnetostriction. The reustls have shown that the increase in the volume fraction of the (Tb, Dy)[Fe.sub.3] phase and the reduction in the grain orientation of the (Tb, Dy)[Fe.sub.2] are the main reasons for the large decrease in the magnetostriction of the (Tb, Dy)[Fe.sub.1.95] alloys with boron addition.

The compound Tb0.3Dy0.7Fe1.95 is conventionally cast and also directionally solidified using zoning and modified Bridgman techniques. The microstructures of the directionally solidified samples are studied using optical microscope, scanning electron microscope/energy dispersive spectroscopy (SEM)/EDS, and correlated with the magnetostriction measured by resistance strain gauges.

The aim of the research work is to present the results of experimental and analytical studies concerning the static and cyclic behavior of Reinforced Concrete (RC) beams retrofitted with externally bonded cementitious composites-Slurry Infiltrated Fiber CONcrete (SIFCON) and Slurry Infiltrated Mat CONcrete (SIMCON). A total of 20 beams of size 125 mm width × 250 mm depth × 3,200 mm length with effective span of 3,000 mm are cast and tested in the laboratory. The laminates of size 125 mm width × 25 mm depth × 2,950 mm length are bonded in between the beam supports. Four of them are control specimens. The study considers two series (series 1 and series 2) of SIFCON and SIMCON retrofitting systems. Static and cyclic responses of all the beams were evaluated in terms of strength, stiffness, ductility ratio, energy absorption capacity factor, compositeness between laminate and concrete, and the associated failure modes. The theoretical moment-curvature relationship for the test specimen and the load-displacement response of the strengthened beams and control beams were predicted by using FEA software ANSYS. A comparison was made between the numerical (ANSYS) with the experimental and theoretical results. Regression analysis was carried out using Statistical Package for the Social Sciences software and validation of present research was done with the data available in the literature. [ABSTRACT FROM AUTHOR]

Clusters, containing between 10 and 1000 atoms, have been investigated in a martensitic secondary hardening ultra-high-strength steel austenitized at 1173 K (900 °C) for 1 hour and tempered at either 768 K or 783 K (495 °C or 510 °C) for 4 or 8 hours using 3D atom probe. The presence of clusters was unambiguously established by comparing the observed spatial distribution of the different alloying elements against the corresponding distribution expected for a random solid solution. Maximum separation envelope method has been used for delineating the clusters from the surrounding 'matrix.' Statistical analysis was used extensively for size and composition analyses of the clusters. The clusters were found to constitute a significant fraction accounting for between 1.14 and 2.53 vol pct of the microstructure. On the average, the clusters in the 783 K (510 °C) tempered sample were coarser by ~65 pct, with an average diameter of 2.26 nm, relative to the other samples. In all samples, about 85 to 90 pct of the clusters have size less than 2 nm. The percentage frequency histograms for carbon content of the clusters in 768 K and 783 K (495 °C and 510 °C) tempered samples revealed that the distribution shifts toward higher carbon content when the tempering temperature is higher. It is likely that the presence of these clusters exerts considerable influence on the strength and fracture toughness of the steel. [ABSTRACT FROM AUTHOR]

The paper presents the results of experimental and analytical studies concerning the flexural strengthening of Reinforced Concrete (RC) beams using externally bonded cement-based composite like Slurry Infiltrated Mat CONcrete (SIMCON) laminates and polymer-based composites like Carbon Fiber Reinforced Polymer (CFRP) laminates. A total of seven reinforced concrete beams were cast and tested in the laboratory over an effective span of 3,000 mm. Five beams were strengthened with bonded SIMCON and CFRP laminates at the bottom under virgin condition and tested until failure; the remaining two beams were used as control specimens. The static responses of all the beams were evaluated in terms of strength, stiffness, ductility ratio, energy absorption capacity factor, compositeness between laminate and concrete, and the associated failure modes. The theoretical moment-curvature relationship for the test specimen and the load-displacement response of the strengthened beams and control beam were predicted using FEA software ANSYS. A comparison was made between the numerical (ANSYS) with the experimental and theoretical results. The results showed that the strengthened beams exhibit increased flexural strength, enhanced flexural stiffness and composite action until failure. [ABSTRACT FROM AUTHOR]

The paper presents the results of experimental and analytical studies concerning the flexural strengthening of RC beams using externally bonded Slurry Infiltrated Mat CONcrete (SIMCON) laminates. The preliminary study of SIMCON laminates was carried out for optimizing the volume fraction (Vf ) and aspect ratio (l/d) of fiber mat. A total of 45 number of laminates of size 125×25×500 mm with different volume fractions (Vf = 4.0%, 4.5%, 5.0%, 5.5% and 6.0%) and different aspect ratios (l/d = 300, 400 and 300 and 400) were cast and tested in the laboratory. A total of five reinforced concrete beams were cast and tested in the laboratory over an effective span of 3,000 mm. Three beams were strengthened with bonded SIMCON laminate at the bottom under virgin condition and tested until failure; the remaining two beams were used as baseline specimens. Static responses of all the beams were evaluated in terms of strength, stiffness, ductility ratio, energy absorption capacity factor, compositeness between laminate and concrete and the associated failure modes. The theoretical moment-curvature relationship for the test specimen and the load-displacement response of the strengthened beams and unstrengthened beams were predicted by using FEA software ANSYS. Comparisons were made between the numerical (ANSYS) and the experimental results. The results showed that the strengthened beams exhibited increased flexural strength, enhanced flexural stiffness and composite action until failure. [ABSTRACT FROM AUTHOR]

This paper explores the effect of Al on the initial permeability of nanocrystalline Fe-Si-Mo-B-Cu-type soft magnetic alloys. It is shown that improved properties, in particular permeability, occur over a small window around 1 at.% of Al addition. Contrary to the earlier reports, our results suggest that the addition of Al promotes higher number density of α-Fe(Si) crystallites as well as higher volume fraction. The 3-dimensional atom probe study indicates that Al primarily partitions in the α-Fe(Si) phase. However, significant segregation of Al is also observed in copper cluster suggesting its role in promoting nucleation of α-Fe(Si) phase. Permeability is shown to evolve as a function of composition due to the competition between the decreasing magnetization of the alloy owing to the incorporation of Al in α-Fe(Si) and increase in the number density and volume of α-Fe(Si,Al) phase. [ABSTRACT FROM AUTHOR]

Abstract: The paper reports the effect of the addition of small amount of Al on the microstructure and properties of HITPERM class rapidly solidified Fe44Co44Zr7B4Cu1 glassy alloy. Using three dimensional atom probe measurements we present evidence for the formation of Cu clusters on annealing in the metallic glass matrix of the Al containing alloy Fe43Co43Al2Zr7B4Cu1. Such clusters are otherwise absent in the parent alloy under similar conditions. The Cu clusters provides heterogeneous nucleation sites for the formation of bcc α′-FeCo phase leading to an increase in number density of this nanocrystalline phase and thereby enhancing the magnetic properties. [Copyright &y& Elsevier]

It had been reported that B has beneficial effects on the magnetostriction of anisotropy compensated Dy0.7Tb0.3Fe2 alloys. In the present work, Dy0.7Tb0.3Fe1.95 and Dy0.7Tb0.3Fe1.95Bx (x=0.1, 0.15, and 0.2) alloys, in the form of 8 mm diameter cylindrical rods, were investigated both in the as-cast and zoned conditions. At 5 kOe dc magnetic field, magnetostriction of ∼1200 and 900 microstrains was observed for zoned samples with x=0 and 0.1, respectively. For zoned samples with x>0.1 and for the as-cast sample of the parent alloy, magnetostriction of ∼500 microstrains was measured. X-ray diffraction of the zoned x=0 and x=0.1 samples showed a strong prevalence of the <112> and the <110> grain orientations; in contrast, the other samples appeared to possess a random grain orientation. Optical and scanning electron microscopy studies revealed a significant increase in the volume fraction of the RFe3 phase with increasing boron content. This increase in the volume fraction of the (Tb,Dy)Fe3 phase and the reduction in the desired grain orientation of the (Tb,Dy)Fe2 phase are attributed to be the reasons for the large decrease in the magnetostriction of the (Tb,Dy)Fe1.95 alloys with boron addition. [ABSTRACT FROM AUTHOR]

Abstract: Crystal structure of the phases, microstructure and magnetocaloric effect were investigated in Gd5Si2(Ge1−x Ga x )2 alloys with x =0, 0.01, 0.02 and 0.03. The phase identification and compositional analysis were carried out by a combination of X-ray diffraction, scanning electron microscopy and electron probe micro-analysis. The Gd5Si2Ge2-type matrix phase having an orthorhombic structure co-exists with Gd5Ge3-type and GdGe-rich phases. Ga was found to have preferentially partitioned to the orthorhombic Gd5Si2Ge2-type matrix phase. Magneto-structural transition temperatures determined from differential scanning calorimetry and thermo-magnetic techniques revealed that Ga substituted alloys exhibit only magnetic transition unlike parent Gd5Si2Ge2 alloy which displays both structural and magnetic transitions. A maximum magnetic entropy change (ΔS)M of 7.0J/kgK was obtained in x =0 alloy for a magnetic field change of 2T and its magnitude was lower in the Ga substituted alloys. [Copyright &y& Elsevier]

Abstract: In this paper, we present the results of structural and photoluminescence (PL) studies on vertically aligned, 20-period In0.33Ga0.67As/GaAs quantum dot stacks, grown by molecular beam epitaxy (MBE). Two different In0.33Ga0.67As/GaAs quantum dot stacks were compared. In one case, the In0.33Ga0.67As layer thickness was chosen to be just above its transition thickness, and in the other case, the In0.33Ga0.67As layer thickness was chosen to be 30% larger than its transition thickness. The 2D–3D growth mode transition time was determined using reflection high-energy electron diffraction (RHEED). Structural studies were done on these samples using high-resolution X-ray diffraction (HRXRD) and cross-sectional transmission electron microscopy (XTEM). A careful analysis showed that the satellite peaks recorded in X-ray rocking curve show two types of periodicities in one sample. We attribute this additional periodicity to the presence of an aligned vertical stack of quantum dots. We also show that the additional periodicity is not significant in a sample in which the quantum dots are not prominently formed. By analyzing the X-ray rocking curve in conjunction with RHEED and PL, we have estimated the structural parameters of the quantum dot stack. These parameters agree well with those obtained from XTEM measurements. [Copyright &y& Elsevier]