An extensive diffusion analysis is presented for binary Ni-X and ternary Ni-Al-X (X = Cr, Mo, Ta, W, Re) systems, which play a crucial role in microstructural evolution and phase stability in Ni-Al-based superalloys. Specifically, we highlight changes in the diffusion coefficients of X in the presence of Al and compare diffusional interactions across systems considered. First-principles calculations, combined with activation energies derived from temperature-dependent experiments, reveal consistent trends in Ni-X systems, with variations in activation energies largely attributed to differences in migration energies. In ternary systems, diffusion coefficients estimated from intersecting diffusion profiles show that the main interdiffusion coefficient of X is comparable to its binary counterpart, with similar activation energies. However, cross-diffusion coefficients are shown to significantly influence fluxes, either enhancing or reducing diffusion lengths depending on the relative directions of diffusing elements. For Ni-Al-Re, a single-profile method is employed to overcome uncertainties in estimating composition gradients at the near-end-member intersecting composition. The diffusion coefficients obtained correlate well with the nature of diffusion paths when represented on Gibbs triangles. To extend these findings, a physics-informed neural network (PINN) optimization method is applied to extract composition-dependent diffusion coefficients across the full composition range. The analysis demonstrates the necessity of incorporating experimentally estimated diffusion coefficients as equality constraints, without which optimization reliability is compromised. Overall, the results establish a robust framework for diffusion studies in Ni-Al-X systems, highlighting the critical role of cross-diffusion effects and constraint-enhanced numerical methods.

Kulkarni et al. [1] commented on our recent work [2], criticising different aspects of the novel pseudo-binary (PB) diffusion couple method. They stated that the interdiffusion flux of an element, which remains constant, is zero, but not its intrinsic flux, whereas we considered both to be nil. We have highlighted the mathematical errors and inconsistencies in their arguments, as their logic on one aspect contradicts their logic in another. The direct estimation of four interdiffusion coefficients in Ref. [3], which they considered to support their comments in Ref. [1], is mathematically incorrect, as it is based on only two or three independent equations (depending on the number of pseudo-binary diffusion profiles considered). In this reply, we validate the pseudo-binary diffusion couple method proposed by us and highlight the self-inconsistencies in the arguments presented by Kulkarni et al. in Ref. [1].

Solving the unresolved problem, the pseudo-binary (or quasi-binary or iso-concentration) diffusion couple method has emerged as an elegant and most frequently used research tool for diffusion analysis in multicomponent systems. This is practiced even in a ternary system for the systematic generation of composition-dependent diffusion coefficients, which is otherwise impossible following conventional methods. However, the analysis for the deviations from an “ideal pseudo-binary diffusion profile” is not standardized yet, leading to confusion in the acceptability of the estimated diffusion coefficients. This study explains the logic behind establishing an augmented Darken and Darken-Manning equation schemes suitable for pseudo-binary diffusion profiles considering experimentally produced diffusion profiles and extracted activity profiles of elements. The correct estimation method is demonstrated by producing pseudo-binary profiles up to a six-element system for the first time, depending on the ideal or non-ideal nature of the diffusion profiles. A re-adjustment factor (RAF) concept is introduced, reflecting on the effect of the non-ideality range on estimated diffusion coefficients. This is demonstrated based on several diffusion couple experiments in multiple systems of technological importance that produce different ranges of ideal, near-ideal, minor, and major non-ideal pseudo-binary diffusion profiles. RAF values provide an ultimate guideline for pseudo-binary diffusion analysis in multicomponent systems depending on the extent of non-ideality and composition range of the main diffusing elements. Additionally, the importance of estimating the tracer and intrinsic diffusion coefficients instead of only interdiffusion coefficients (reported mostly) is substantiated by estimating all types of diffusion coefficients when relevant.

This study shows the beneficial effect of Pt addition to the ((3+gamma)-NiCrAlY coating. Adding Y in NiCrAl increases oxide growth kinetics but improves spallation resistance. Pt with Y does not change the oxidation rate compared to only adding Y but significantly reduces spallation when cooled to room temperature. Continuous layers of Al2O3 and Cr2O3, along with other oxides such as YAlO3, NiCr2O4, and NiAl2O4, are observed. Moreover, Pt addition reduces the thickness of the interdiffusion zone where Al goes through an uphill diffusion profile, minimizing Al loss and significantly decreasing the growth of deleterious TCP phases.

Present work deals with fabrication of superhard titanium boride coating on titanium surface with preplaced amorphous boron layer using high power diode laser alloying. Amorphous boron instantaneously converts into crystalline boron by the effect of high-power laser interaction, which rapidly drives the boron species into titanium liquid pool and form titanium boride precipitates by its convective flow. Negative Gibbs free energy (Delta G) and enthalpy (Delta H) of amorphous boron crystallization reaction introduces the concept of laser induced self-propagation synthesis. Gibbs free energy (Delta G) for the chemical reactions between Ti and B was calculated to confirm the spontaneous formation of titanium boride compound phases. The diffusion coefficient and activation energy were estimated to understand the phase formation and microstructural evolution. The structural phase, microstructure, microhardness and wear resistance of the laser borided titanium was investigated by XRD, optical and scanning electron microscopy, EDAX, Vickers microhardness analysis and linear reciprocating wear testing. The laser alloyed coating across the cross section shows formation of dendrites and whisker like microstructures. Average microhardness of 800-1600 HV0.2 was measured at different cross-sectional depths and an extreme hardness of about 3800-4700 HV0.2 was obtained in some regions of boron precipitates. The results showed a high negative value of Gibbs free energy of about -250 kJ/mol and -170 kJ/mol at similar to 2000 degrees C respectively which confirms the spontaneity of TiB2 and TiB phase formation. The activation energy of the titanium boride is estimated to be 140 kJ/mol. The laser borided coating with the formation of TiB and TiB2 phases could be useful for surface engineering applications.

The present study illustrates the effect of varying Cr content in Co51- xNi30Al10Mo5Nb2Ti2Cr x ( x = 2, 5, and 8 at.-%) compositionally complex alloys (CCAs). STEM-EDS analysis suggests a change in Mo partitioning from equal in both the phases (γ and γ′) in CCA-2Cr to the γ phase in CCA-5Cr and CCA-8Cr alloys. This peculiar compositional partitioning with Cr content beyond 2% brings a change in γ′ precipitate morphology from cuboidal to spheroidal in CCAs. The shape change-induced reduction in strain energy rendered a decrease in γ′ coarsening rate by ∼ 1/2, i.e. from 11.5 to 4.6 nm3/s in the CCA-2Cr and CCA-8Cr alloys, respectively. All three alloys show an anomalous increase in 0.2% proof stress (PS) with temperature and achieve peak values at 770°C.

In this study, we investigated climatic parameters and predicted future changes in precipitation and atmospheric temperature levels based on RCP4. 5/8.5 scenarios in all cardamom-coffee hot spots of southern India. Our results showed more precipitation levels and patterns occurred in Cardamom hills (Kerala), followed by lower Puleny hills in Tamil Nadu. The least variation in precipitation levels has been noticed for temperate upper Puleny hills and Kodagu hills in Karnataka. RCP4.5/8.5 scenario analysis showed greater variability in precipitation, up to 180% increase and 90% decrease for all hot sports. The scenario analysis also predicted extreme temperature variations ranging from 0.5 to 8.5°C increase for the entire study region. A significant change in coffee yield and quality has been recorded over the last 30 years. Increased yield trends in coffee were noticed for Cardamom hills (CH) and Kodagu hills, but significantly lower coffee production was observed for lower Pulney hills. The mixed response of yield variability in coffee has been primarily attributed to the ongoing changing climatic factors. Ecophysiological studies of coffee, cardamom, and black pepper have proved that coffee would adapt well to future challenging climatic conditions, closely followed by cardamom and black pepper. Since all the coffee-cardamom hot spots in southern India undergoes considerable change in precipitation levels and pattern, necessary precautions, including water and irrigation management strategies, must be given utmost priority to increase the crop yield sustainability of these delicate cardamom-coffee hot spots in India.

Intensive cardamom cultivation in Indian Cardamom hills (ICH) has been related to severe ecological and environmental implications that can challenge the long-term sustainability of cardamom. This research study and analysis proposes a novel system approach for sustainable agroecological production of cardamom in southern India. The effects of intensive cardamom cultivation on its forest environment had been significant. A considerable increase in surface air temperature was observed in the ICH during the last three decades (1990–2020). The climate of the Cardamom hill reserves (CHR) has a very high variability of daily cycles (surface air temperature and relative humidity) compared to low variability of yearly cycles, which helped minor and major pests and diseases occur and spread throughout the season. The current hydrothermal condition of the soil fostered the occurrence of soil insect pests, resulting in higher pesticide use. Epiphytes peculiar to the CHR forest have been eliminated due to repeated, intense shade lopping of each tree. Variability occurred in cardamom growth and development and yield can be attributed to changes in the microclimatic environment prevailing in the micro habitats of the sloping hillsides. This study has revealed the possible link and various dimensions between the intensive growing practices that were positively reflected in its local climate and production system. The 75% shade level under the cardamom canopy influences the cardamom microclimatic conditions, the relative humidity close proximity with panicles was maximum (88.9%), and the mean air temperature was minimum (18.4°C). On the contrary, the relative humidity at canopy top was reduced (78.7%) but the mean air temperature was still high (27.4°C). This study also suggests that future energy transfers in the CHR production system must be understood for improving the long-term agricultural sustainability of cardamom cultivation in the ICH.

In this work a novel multiphase titanium metal matrix composite (TMMC) coating was developed by high power diode laser assisted alloying of Cp-Ti with the preplaced Boropak powder consisting of B 4 C and SiC ceramic particles. The XRD, optical microscopy, scanning electron microscopy, EDAX, microhardness and wear testing was performed out to investigate the alloyed coating. Under the influence of multipass laser alloying, the B 4 C and SiC ceramic particles decompose to yield boron, silicon and carbon species that reacted with molten titanium to form TiB 2 , TiB, TiC and Ti 5 Si 3 phases in the laser alloyed coating. In addition, the un-melted B 4 C and SiC the ceramic particles dispersed in the titanium matrix created the TMMC. The microstructure of the alloyed coating consists of dendrites and coralline-like structure. The tips of the coralline-like structure are in size 150 to 500 nm. A hardness of 800 to 2200 HV 0.2 was measured at different regions of laser alloyed coating cross section due to the multiphase TiB 2 , TiB, TiC and Ti 5 Si 3 ceramic compound formation. To correlate phase formation and microstructural features the surface temperature evolved during laser alloying process was estimated by a simple equation, and activation energy for the laser melted track was calculated using the Arhennius equation. The linear reciprocating wear testing indicated laser alloyed coating showed a low wear rate of 1.623 х 10 -4 mm 3 /N.m compared to the untreated titanium.

CoSb based compounds have gained much importance in the fields of thermoelectric devices. In this work, we have conducted the solid–state conventional bulk diffusion couple experiments. To study the phase evolutions, Co/Sb diffusion couples are annealed at 450–550 °C. The interdiffusion zone is analysed using field emission gun equipped scanning electron microscope and the composition measurements are done in electron probe micro−analyser to confirm the growth of various product phases. The marker experiment indicates that the CoSb3 phase grows mainly by diffusion of Sb in the binary Co–Sb system. Growth of the CoSb3 phase is discussed based on assessment correlating the difference in mobilities of species with the high homologous temperature, crystal structure of the phase, and the concept of sublattice diffusion mechanism in line compounds.

Fe/Mo bulk diffusion couples are annealed at 1050-1200 degrees C to study the growth and diffusion behaviour of mu phase in the Fe-Mo system. Parabolic growth constants and integrated interdiffusion coefficients are determined in the mu phase. The activation energies for the growth of mu phase and for the integrated interdiffusion coefficients are estimated as 228 +/- 22 and 733 +/- 10 kJ/mol, respectively. The relatively high activation energy for interdiffusion in mu phase, determined at high homologous temperature of 0.8-0.9, indicates that mu phase grows by lattice diffusion. Phase boundary compositions, measured by EPMA, indicates the homogeneity range of mu phase to be similar to 3 at.% higher towards the Fe-rich side (i.e., 36 at.% Mo) as compared to the reported composition of 39-44 at.% Mo in the phase diagram.

A strong influence of Ni content on the diffusion-controlled growth of the (Cu,Ni)(3)Sn and (Cu,Ni)(6)Sn-5 phases by coupling different Cu(Ni) alloys with Sn in the solid state is reported. The continuous increase in the thickness ratio of (Cu,Ni)(6)Sn-5 to (Cu,Ni)(3)Sn with the Ni content is explained by combined kinetic and thermodynamic arguments as follows: (i) The integrated interdiffusion coefficient does not change for the (Cu,Ni)(3)Sn phase up to 2.5 at.% Ni and decreases drastically for 5 at.% Ni. On the other hand, there is a continuous increase in the integrated interdiffusion coefficient for (Cu,Ni)(6)Sn-5 as a function of increasing Ni content. (ii) With the increase in Ni content, driving forces for the diffusion of components increase for both components in both phases but at different rates. However, the magnitude of these changes alone is not large enough to explain the high difference in the observed growth rate of the product phases because of Ni addition. (iv) Kirkendall marker experiments indicate that the Cu6Sn5 phase grows by diffusion of both Cu and Sn in the binary case. However, when Ni is added, the growth is by diffusion of Sn only. (v) Also, the observed grain refinement in the Cu6Sn5 phase with the addition of Ni suggests that the grain boundary diffusion of Sn may have an important role in the observed changes in the growth rate.

The interfacial reactions between several Au(Cu) alloys and pure Sn were studied experimentally at 200°C. Amounts of Cu in the AuSn4 and AuSn2 phases were as low as 1 at.%. On the basis of these experimental results there is no continuous solid solution between (Au,Cu)Sn and (Cu,Au)6Sn5. The copper content of (Au,Cu)Sn was determined to be approximately 7–8 at.%. Substantial amounts of Au were present in the (Cu,Au)6Sn5 and (Cu,Au)3Sn phases. Two ternary compounds were formed, one with stoichiometry varying from (Au40.5Cu39)Sn20.5 to (Au20.2Cu59.3)Sn20.5 (ternary “B”), the other with the composition Au34Cu33Sn33 (ternary “C”). The measured phase boundary compositions of the product phases are plotted on the available Au–Cu–Sn isotherm and the phase equilibria are discussed. The complexity and average thickness of the diffusion zone decreases with increasing Cu content except for the Au(40 at.%Cu) couple.

Interdiffusion, intrinsic, tracer and impurity diffusion coefficients are calculated in the Pd–Pt system. Interdiffusion coefficients are more or less insensitive to composition change. Activation energy varies in the range of 324–353 kJ/mol. Impurity diffusion coefficients calculated in this study and available tracer diffusion coefficients in pure elements indicate that Pd has higher diffusion rate compared to Pt in pure Pd, whereas, both the elements have similar diffusion rates in Pt. Kirkendall marker experiments indicate that Pd has much higher diffusion rate in Pd3.5at.%Pt compared to Pt.

Growth mechanism of phases and atomic mechanism of diffusion are discussed in the Pd-Sn system. The Kirkendall marker plane location indicates that the PdSn4 phase grows because of diffusion of Sn. Atomic arrangement in the crystal indicates that Sn can diffuse through its own sublattice but Pd cannot diffuse unless antisites are present. The negligible diffusion of Pd indicates the absence of Pd antisites. The activation energy value indicates that the contribution from grain boundary diffusion cannot be neglected although experiments were conducted in the homologous temperature range of 0.7–0.79.

In this study we analyzed climate and crop yields data from Indian cardamom hills for the period 1978–2007 to investigate whether there were significant changes in weather elements, and if such changes have had significant impact on the production of spices and plantation crops. Spatial and temporal variations in air temperatures (maximum and minimum), rainfall and relative humidity are evident across stations. The mean air temperature increased significantly during the last 30 years; the greatest increase and the largest significant upward trend was observed in the daily temperature. The highest increase in minimum temperature was registered for June (0.37°C/18 years) at the Myladumpara station. December and January showed greater warming across the stations. Rainfall during the main monsoon months (June–September) showed a downward trend. Relative humidity showed increasing and decreasing trends, respectively, at the cardamom and tea growing tracts. The warming trend coupled with frequent wet and dry spells during the summer is likely to have a favorable effect on insect pests and disease causing organisms thereby pesticide consumption can go up both during excess rainfall and drought years. The incidence of many minor pest insects and disease pathogens has increased in the recent years of our study along with warming. Significant and slight increases in the yield of small cardamom (Elettaria cardamomum M.) and coffee (Coffea arabica), respectively, were noticed in the recent years.; however the improvement of yield in tea (Thea sinensis) and black pepper (Piper nigrum L.) has not been seen in our analysis.

The recent intensification of small cardamom ( Elettaria cardamomum Maton) farming, and the prospects of intensification, will have the major detrimental impacts on the Indian cardamom hills (ICH) ecosystem. The increased (4 fold) cardamom production during the past 30 years was associated with a several fold increase in the consumption of fertilizers and pesticides as well as drastic reduction in erstwhile rainforest land and canopy cover. Based on simple linear extension of past trends, and the anticipated future demand of cardamom would be associated with approximately 3 fold increase in both nitrogen and phosphorus fertilizer rates as well as pesticides ( 4-5 fold increase in number of spray rounds) and further reduction in forest canopy cover (40%). These projected changes would have dramatic impacts on the functioning of the cardamom ecosystem because of complete loss of biodiversity and land and forest degradation. The largest impacts would be on fresh water ecosystem, which would be greatly eutrophied by high rates of nitrogen and phosphorus release from cardamom and tea plantations, and contaminated with various toxic pesticides. These detrimental environmental impacts of intensive cardamom agriculture can be minimized only if there is much more efficient use and recycling of nutrients between forest and soil.

The southern Western Ghats tropical montane cloud forest sites (Gavi, Periyar, High wavys and Venniyar), which are characterized by frequent or seasonal cloud cover at the vegetation level, are considered one of the most threatened ecosystems in India and the world. Three out of four montane cloud forest sites studied in the southern Western Ghats had experienced diminishing trends of seasonal average and total rainfall, especially during summer monsoon season. The highest level of reduction for summer monsoon season was observed at Gavi rainforest station (>20 mm/14 years) in Kerala followed by Venniyar (>20 mm/20 years) site in Tamil Nadu. Average annual and total precipitation increased during the study period irrespective of the seasons over Periyar area, and the greatest values were recorded for season 2 (>25 mm/28 years). Positive trends for winter monsoon rainfall has been observed for three stations (Periyar, High wavys and Venniyar) except Gavi, and the trend was positive and significant (90%) for Periyar and High wavys. Increase in summer monsoon rainfall was observed for Periyar site and the trend was found to be significant (95%).