Dendritic Regions Research Articles

Laser surface alloying of Hastelloy X superalloy with Amdry 365 powder: Microstructural evolution and microhardness

Laser surface alloying is a surface modification technique that melts coat powder and substrate with high laser power density. This study aims to improve the properties of Hastelloy X, a Ni-based superalloy used for gas turbine components, by applying a NiCoCrAlY coating using laser surface alloying. The purpose of this study was to investigate the process parameters including laser scanning speed, laser power, and stand-off distance on the microstructure and microhardness of the alloying zones. The findings indicate that different microstructures were formed in different alloying zones such as cellular, columnar, and equiaxed. The results also revealed the presence of β and γ phases in the dendritic and interdendritic regions. The microhardness at the interface was higher than that of the other alloying areas due to the increased content of the Mo element. This study concluded that the properties of Hastelloy X can be improved by using NiCoCrAlY powder through a laser alloying process.

Influence of Al2O3 and h-BN on Wear and Corrosion Performance of IN625 Nickel-Based Coating

IN625 offers high-temperature oxidation resistance, wear resistance, and stable chemical properties. To improve the corrosion and wear resistance of the Q345B steel surface, two types of metal matrix composites (IN625 + 1% Al2O3 and IN625 + 1% h-BN) were applied to the substrate surface using the laser cladding process. This study analyzed the hardness, electrochemical corrosion, friction, and wear properties of both the laser-clad specimens and the substrates. The results show that (1) the hardness and wear resistance of the fusion-coated coating were significantly improved compared with the base material. Notably, the hardness increased by 19%, and the coefficient of friction decreased by 41% compared with the IN625 + 1% h-BN coating. Furthermore, the hardness and wear resistance of the IN625 + 1% h-BN coating were superior to those of the IN625 + 1% Al2O3 coating, attributed to the formation of eutectic compounds such as NiB and Ni2B in the dendritic region. (2) The corrosion resistance of the IN625 + 1% Al2O3 coating exceeds that of the IN625 + 1% h-BN coating and is also superior to that of the substrate. This improvement is primarily attributed to the addition of Al2O3, which enhances solid solution strengthening within the dendritic crystals of the fused-coating layer, reduces the percentage content of inclusions, and elevates the corrosion resistance of the coatings.

Investigation on non-uniform oxidation behaviour in dendritic and interdendritic regions in a single-crystal Ni-based superalloy

Investigation on non-uniform oxidation behaviour in dendritic and interdendritic regions in a single-crystal Ni-based superalloy

Enhancing the anodic dissolution uniformity of dendritic-structured refractory high entropy alloys using a split electrolytic cell with a deep eutectic solvent

The attainment of uniform anodic dissolution in dendritic-structured refractory high entropy alloys (RHEAs) during the electropolishing process is essential for their utilization in high-precision components. Nevertheless, the intricate microstructures of these materials impede uniform dissolution, resulting in suboptimal surface quality. In this work, based on a choline chloride-based deep eutectic solvent and suitable polarization parameters selected by linear scanning voltammetry, a split electrolytic cell (SEC) was proposed to alter the traditional integrated electrolytic cell (IEC) to enhance the anodic dissolution uniformity of dendritic-structured RHEAs. A much smoother surface with Ra of 0.233 μm and a smaller height discrepancy of 0.8 μm was obtained, compared to those processed in IEC at the same condition. The non-uniform anodic dissolution was mainly attributed to the cathode-forming (hydroxide ion (OH−), dissolution of tungsten (W) in the dendrite region under the attack by OH−, and the formation of by-product, i.e., the water molecule. The positive impact of SEC on dissolution uniformity could be ascribed to its role in inhibiting OH− from interacting with the anode, as well as to the enhancement of solution acidity on the anode side, which facilitated the dissolution of metal oxides. The suggested reaction pathway was subsequently validated through experiments with controlled water concentration and assessing of electrochemical kinetics. Finally, the effects of SEC under different parameters were demonstrated. This work provides valuable insight into the precise, micro/nanoscale manufacturing and green electrochemical surface finishing of RHEAs in the future.

Microstructural Stability and High-Temperature Oxidation Behavior of Al0.25CoCrCuFeNi High Entropy Alloy

Al0.25CoCrCuFeNi is a high-entropy alloy composed of transition metals, specifically designed for high-temperature applications owing to its favorable mechanical properties, high melting point, and excellent high-temperature resistance. This alloy has been identified as a promising material for space exploration, particularly in the fabrication of combustion chambers and rocket nozzles by the National Aeronautics and Space Agency. Ongoing alloy development involves modifying the elemental composition. This study reduced aluminum content in the equiatomic AlCoCrCuFeNi alloy to Al0.25CoCrCuFeNi, followed by isothermal oxidation treatments at 800, 900, and 1000℃. A series of experiments were conducted to investigate the microstructure stability and oxidation behavior of the Al0.25CoCrCuFeNi alloy. The alloying elements were melted using a single DC electric arc furnace, followed by homogenization at 1100°C for 10 hours in an inert atmosphere. Subsequently, samples were cut into coupons for isothermal oxidation testing at the desired temperatures for 2, 16, 40, and 168 hours. The oxidized samples were characterized using XRD (x-ray diffraction), SEM (scanning electron microscopy) equipped with EDS (energy-dispersive X-ray spectroscopy), optical microscopy, and Vickers hardness testing. The as-homogenized alloy consisted of two constituent phases: an FCC (face-centered cubic) phase in the dendritic region and a copper-rich FCC phase in the inter-dendritic region. The oxides formed during the oxidation process included Al2O3, Cr2O3, Fe3O4, CoO, CuO, NiO, and spinel oxides (Co,Ni,Cu)(Al,Cr,Fe)2O4), with distinct formation mechanisms at each temperature.

A mechanism on multiscale heterogenous deformation of nickel-based single crystal superalloys unraveled by time-of-flight neutron diffraction technology

Time-of-flight (TOF) neutron diffraction technology is a powerful tool for acquiring rich diffraction information on the multiscale microstructures and stresses of nickel-based single crystal superalloys. In this study, the tensile deformation behaviors of DD426 superalloy at 760 °C were investigated by TOF neutron diffraction. Combined with electron backscatter diffraction technology, the multiscale deformation heterogeneity between γ/γ' phases and dendritic/interdendritic regions was simultaneously characterized for the first time. Our experiments revealed a significant misorientation difference and the existence of a long-range stress field in the adjacent area between the dendritic and interdendritic regions after tensile deformation at 760 °C. The misorientation angles of crystal planes along the loading direction between the dendritic and interdendritic regions in the deformed alloy was approximately 1.6 ± 0.6° This misorientation can be attributed to the geometrically necessary dislocations (GNDs) concentrated in the adjacent area between the two regions with densities of approximately 1014 m-2. In addition, the lattice strains of both γ' and γ showed a compressive–tensile transition from the dendritic to interdendritic regions, balanced with a long-range stress field. The pile-up GNDs in the adjacent area between the two regions contributed to the existence of long-range stress fields. This study highlights that TOF neutron diffraction technology may reveal well the heterogeneous deformation mechanisms via the formation of both GNDs and pile-up in the adjacent interdendritic/dendritic area of single crystal superalloys.

The Effect of Optimized Substrate Orientation on Layer Step in Laser Metal Deposition of Single-Crystal Nickel-Base Superalloys.

Laser metal deposition is a promising way to repair the surface defects of single-crystal components in turbo engines. Understanding the mechanisms and improving the efficiency of the repair have been long-standing problems. In this study, the influence of the substrate orientation on the laser metal deposition (LMD) was investigated and its effect on repair layer-step was examined. LMD experiments were conducted on single crystal superalloys with a normal substrate orientation (001)/[100] and with an optimized substrate orientation (101)/[101¯]. It reveals that the laser cladding with the optimized orientation leads to a larger height of the [001] dendrite region than that with the normal orientation. The calculated results of the growth velocity, thermal gradient, and susceptibility to CET in the dendrite-preferred growth direction indicate that, for the (101)/[101¯] orientation, the [001]/[100] boundary is located at relative high position in each layer, which not only decreases the formation ability of stray grain significantly, but also eliminates the appearance of the maximum susceptibility. This makes the necessary dilution position much higher, and thus, a large cladding step can be selected. Our findings could find potential applications in laser repair of single-crystal components.

Statistical modeling and optimization of clad geometry in laser cladding of Amdry 365 on Hastelloy X superalloy with response surface methodology

The aim of this study is to statistically investigate and optimize the laser cladding process of Hastelloy X superalloy using NiCoCrAlY powder (Amdry 365). In this study, response surface methodology was used to investigate the influence of laser input variables such as scanning velocity, laser power, and duty cycle on the clad geometry (including height, width, and angle) and dilution ratio. The results indicate that with increasing duty cycle and laser power, the clad width increases significantly, while the clad height increases slowly. However, increasing the scanning velocity leads to a decrease in the width and height of the clad. Furthermore, the clad angle and dilution ratio increase with increasing input parameters. The results of variance analysis shows that laser scanning velocity had the most significant impact on clad height, angle and dilution ratio, while laser power had the greatest influence on clad width. The laser power of 321.3 W, the scanning velocity of 6.3 mm/s and the duty cycle of 76 % proved to be the optimal input parameters. An experimental test was carried out to validate the optimal conditions based on the optimization responses. The validation results show that the developed models are able to describe the responses with an accuracy of less than 9 % error. The EDS analysis performed in the cladding zone of the optimum specimen showed the presence of the β phase in the dendritic region and the γ phase in the interdendritic region.

Effect of multi-element synergistic addition on the microstructure evolution and performance enhancement of laser hot-wire cladded Fe-based alloy

To satisfy the requirements of hardness and corrosion resistance for laser additive manufacturing of hydraulic supports, this study applied the synergistic addition of C, B, Cr, Ni, Nb and Mo elements in Fe-based alloys. The multi-phases, martensite + austenite + ferrite were designed. The microstructure, hardness and corrosion resistance of the coatings were analyzed. Increasing the C and B contents could significantly increase the hardness of the coatings, while the corrosion resistance was decreased. The corrosion resistance of the coatings was determined by the Cr contents. However, increasing the Cr contents to 20.0 wt % resulted in the ferrite structure with lower hardness (21 HRC). The coatings with 0.25 wt % C, 1.2 wt % B and 19.0 wt % Cr showed the optimal matching of hardness (56 HRC) and corrosion resistance (survived in neutral salt spray test≥300h). The resulted coatings were mainly consisted of dendritic structure. Fine lath martensite phase was dominant in the dendrite regions. The interdendritic regions were consisted of nano-sized intermetallics with a mixture of σ+Nb + FeNb + Cr2Nb+(Fe,Cr)2B + NbC compounds. These interdendritic regions (14.2 GPa) showed higher hardness than that of the dendritic regions (7.1 GPa). The high Cr contents with finer dendritic structures were the major mechanisms for the excellent combination of hardness and corrosion resistance. The precipitation and growth mechanisms of the interdendritic phases were elaborated. This work provides a valuable reference for laser hot-wire cladding to prepare Fe-based alloys with high hardness and excellent corrosion resistance.

Temperature Effect on Deformation Mechanisms and Mechanical Properties of Welded High-Mn Steels for Cryogenic Applications.

High-manganese steel (high-Mn) is valuable for its excellent mechanical properties in cryogenic environments, making it essential to understand its deformation behavior at extremely low temperatures. The deformation behavior of high-Mn steels at extremely low temperatures depends on the stacking fault energy (SFE) that can lead to the formation of deformation twins or transform to ε-martensite or α'-martensite as the temperature decreases. In this study, submerged arc welding (SAW) was applied to fabricate thick pipes for cryogenic industry applications, but it may cause problems such as an uneven distribution of manganese (Mn) and a large weldment. To address these issues, post-weld heat treatment (PWHT) is performed to achieve a homogeneous microstructure, enhance mechanical properties, and reduce residual stress. It was found that the difference in Mn content between the dendrite and interdendritic regions was reduced after PWHT, and the SFE was calculated. At cryogenic temperatures, the SFE decreased below 20 mJ/m2, indicating the martensitic transformation region. Furthermore, an examination of the deformation behavior of welded high-Mn steels was conducted. This study revealed that the tensile deformed, as-welded specimens exhibited ε and α'-martensite transformations at cryogenic temperatures. However, the heat-treated specimens did not undergo α'-martensite transformations. Moreover, regardless of whether the specimens were subjected to Charpy impact deformation before or after heat treatment, ε and α'-martensite transformations did not occur.

Microstructural stability and mechanical properties of the as-cast and heat-treated newly developed TiNbCrTa refractory complex concentrated alloy

In this study, a TiNbCrTa refractory complex concentrated alloy (RCCA) was prepared using vacuum arc remelting. The microstructural evolution and mechanical properties of both as-cast and heat-treated RCCA samples were analyzed. Heat treatment (HT) was performed at 800–1200 °C for 1 h in a vacuum-sealed environment. These samples exhibited a formation of Cr2Nb and Cr2Ti Laves phases. A variation in elemental distribution was observed, with interdendritic (ID) regions showing higher fractions of Ti and Cr, while the dendritic regions had a greater concentration of Ta and Nb. Micro-segregation at the IDs was confirmed through energy dispersive x-ray spectroscopy mapping, which inferred the formation of Cr- and Ti-rich phases during HT at 800–1200 °C. High-temperature HT at 1200 °C for 1 h led to the evolution of the hcp omega phase. Prolonged HT at 1200 °C for 96 h resulted in the evolution of a Cr-rich Laves phase (Cr2Ta), which was homogeneously distributed within the microstructure, indicating an unstable microstructure. Furthermore, despite prolonged HT, a variation in the elemental distribution persisted due to the presence of dendritic and ID regions. Electron backscattered diffraction analysis revealed the presence of bcc and hcp phases in the dendritic and ID regions, respectively, of the as-cast and HTed samples. The as-cast samples demonstrated a high compressive strength of approximately 2 GPa. Micro-hardness values increased with the HT temperature up to 1000 °C. Further increases under HT conditions did not significantly reduce the microhardness value, whereas prolonged HT at 1200 °C led to an increase in the microhardness value. Overall, the newly developed TiNbCrTa RCCA exhibited high-strength behavior even after the phase transformation.

The microcrack inhibition and mechanical properties of an in-situ synthesized refractory high-entropy alloy fabricated by additive manufacturing

A crack-free refractory high-entropy alloy (RHEA), composed of (Cr25Mo25Nb25V25)99C1 was synthesized in-situ from blended elemental powders using laser directed energy deposition (DED). This study revealed that a minor addition of carbon effectively enhances the grain-boundary cohesion of the DEDed RHEA, thereby mitigating microcrack propagation along the grain boundaries during the additive manufacturing process. Notably, the DEDed RHEA exhibited exceptional high-temperature mechanical properties, highlighted by a yield strength of 787 MPa at 1000 °C along with sustained strain-hardening capacity, surpassing other additively manufactured high-entropy alloys reported to date. The remarkable high-temperature strength of the DEDed RHEA can be attributed to the potent pinning effect exerted on dislocations within both dendritic and interdendritic regions at elevated temperature. This effect stems from severe lattice distortion, local chemical fluctuations (LCFs), solute atom pinning, and dislocation interactions. The method employed to inhibit microcrack formation, along with the elucidation of the high-temperature strengthening mechanism, opens avenues for the fabrication of RHEAs tailored for high-temperature structural applications.

Different Numbers of Conjunctive Stimuli Induce LTP or LTD in Mouse Cerebellar Purkinje Cell.

Long-term depression (LTD) of synaptic transmission at parallel fiber (PF)-Purkinje cell (PC) synapses plays an important role in cerebellum-related motor coordination and learning. LTD is induced by the conjunction of PF stimulation and climbing fiber (CF) stimulation or somatic PC depolarization, while long-term potentiation (LTP) is induced by PF stimulation alone. Therefore, it is considered that different types of stimulation induce different types of synaptic plasticity. However, we found that a small number of conjunctive stimulations (PF + somatic depolarization of PC) induced LTP, but did not induce LTD of a small size. This LTP was not associated with changes in paired-pulse ratio, suggesting postsynaptic origin. Additionally this LTP was dependent on nitric oxide. This LTP was also induced by a smaller number of physiological conjunctive PF and CF stimuli. These results suggested that a larger number or longer period of conjunctive stimulation is required to induce LTD by overcoming LTP. Ca2+ transients at the PC dendritic region was measured by calcium imaging during LTD-inducing conjunctive stimulation. Peak amplitude of Ca2+ transients increased gradually during repetitive conjunctive stimulation. Instantaneous peak amplitude was not different between the early phase and late phase, but the average amplitude was larger in the later phase than in the early phase. These results show that LTD overcomes LTP, and increased Ca2+ integration or a number of stimulations is required for LTD induction.

Corrosion resistance of FeCrMnxAlCu high-entropy alloys in 0.5M H2SO4 solution

In this study, FeCrMnxAlCu high-entropy alloys with varying Mn contents (x = 2.0, 1.5, 1.0, 0.5, and 0) were prepared using a vacuum arc melting furnace. The phase structure and microstructure of the alloys before and after corrosion were characterized via X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The corrosion resistance of the alloys in a 0.5 M H2SO4 solution was comprehensively evaluated through potentiodynamic polarization, electrochemical impedance spectroscopy, immersion tests, white light interferometry, and X-ray photoelectron spectroscopy. Microstructural characterization results revealed that the FeCrMnxAlCu high-entropy alloys exhibited mixed FCC and BCC phase structures and featured typical dendritic and interdendritic regions. Corrosion tests indicated that as the Mn content decreased, the corrosion resistance of the high-entropy alloys improved, and the corrosion type transitioned from dendritic to interdendritic. Among these alloys, the FeCrAlCu high-entropy alloy exhibited the highest corrosion resistance, with the highest positive corrosion potential (Ecorr = −0.11 V), the lowest corrosion current density (Icorr = 1.02 × 10−5 A∙cm2), minimal corrosion depth, and the lowest corrosion rate (0.1592 mm/y). After corrosion, a composite oxide protective film was formed on the alloy surface, effectively hindering further penetration of the H2SO4 solution and exhibiting excellent corrosion resistance.

Recrystallization behavior of a high γ′-fraction Ni-based single crystal superalloy induced by residual strain

The static recrystallization (SRX) of the designed high γ′-fraction Ni-based single crystal superalloy (SX) AlloyX was investigated. The three-dimensional SRX threshold of AlloyX involves plastic strain – deformation temperature – heat treatment temperature established by isothermal deformation and heat treatment tests. The influence of different dislocation configurations obtained at different deformation temperatures on critical SRX temperature was analyzed. The high-density entangled dislocations were observed to gradually transition into low-angle grain boundaries at heat treatment temperature within the γ-channel, potentially serving as the primary driving force for the SRX of AlloyX. Compared with the lower γ′-fraction SX DD32, it is further determined that the preferential dissolution of the small-sized γ′ in the interdendritic region (IDR) caused by high Al is the important factor that induces the recrystallization to occur preferentially in the IDR of AlloyX rather than the dendrite region (DR).

Functional architecture of intracellular oscillations in hippocampal dendrites

Fast electrical signaling in dendrites is central to neural computations that support adaptive behaviors. Conventional techniques lack temporal and spatial resolution and the ability to track underlying membrane potential dynamics present across the complex three-dimensional dendritic arbor in vivo. Here, we perform fast two-photon imaging of dendritic and somatic membrane potential dynamics in single pyramidal cells in the CA1 region of the mouse hippocampus during awake behavior. We study the dynamics of subthreshold membrane potential and suprathreshold dendritic events throughout the dendritic arbor in vivo by combining voltage imaging with simultaneous local field potential recording, post hoc morphological reconstruction, and a spatial navigation task. We systematically quantify the modulation of local event rates by locomotion in distinct dendritic regions, report an advancing gradient of dendritic theta phase along the basal-tuft axis, and describe a predominant hyperpolarization of the dendritic arbor during sharp-wave ripples. Finally, we find that spatial tuning of dendritic representations dynamically reorganizes following place field formation. Our data reveal how the organization of electrical signaling in dendrites maps onto the anatomy of the dendritic tree across behavior, oscillatory network, and functional cell states.

Microstructural Evolution of Quaternary AlCoCrNi High-Entropy Alloys during Heat Treatment.

This study examines the microstructural evolution and mechanical properties of quaternary AlCoCrNi high-entropy alloys after heat treatment at 873 K for 72 and 192 h. The changes in nanostructure and phase transformation based on the heat treatment duration were as follows: B2 dendrite + BCC interdendrite and sigma phases after 72 h; B2 dendrite and interdendritic sigma phases + BCC after 192 h. After annealing, the morphology of the dendritic region shifted from spherical to needle-like, and the interdendritic region transformed from a spinodal-like to a plate-like morphology. Additionally, a phase transformation was observed in the dendritic regions of the annealed alloys at the nano-scale. The presence of the sigma phase in AlCoCrNi high-entropy alloys significantly improved the yield strength to around 1172 MPa; nevertheless, it decreased the compressive strain rapidly to 0.62%.

Effect of solid solution heat treatment duration on microstructure evolution and the high temperature and low stress creep properties of a low-cost fourth-generation single crystal superalloy

Low-cost Ni-based single crystal superalloy with high performance attracted much attention to the researchers in recent years. A Ru-free low-cost fourth-generation single crystal superalloy was designed in this study, which was rarely reported previously. This study mainly focused on the effect of solid solution heat treatment duration on the microstructure evolution and high temperature and low stress creep properties on the experimental superalloy. By the metallographic method, it was revealed that the dendritic segregation was gradually eliminated with the increasing solid solution heat treatment duration. Segregation of Al and Ta were well homogenized as well as W. Segregation of Re could still be observed after 32 h solid solution heat treatment. Quantity and fraction of pores increased, which has a significant influence on the creep properties. Compositional variation between dendritic and inter-dendritic region was the main factor that caused the qualitative difference in the size and volume fraction of the γ' phase. Gap of the γ' size and volume fraction between dendritic cores and inter-dendritic region after solid solution heat treatment became minor. Homogeneous dislocation networks formed during the creep test and the ruptured dislocation networks of the specimen subjected to 32 h solid solution heat treatment were found. In the tertiary stage of the creep test, the primary creep deformation mechanism is the super-dislocations with Burgers vector of a 〈010〉 shearing the rafted γ' phases. The specimen subjected to 16 h solid solution heat treatment has the optimal creep performance, followed by those subjected to 32 h and 8 h, respectively.

Effect of Cooling Method on Microstructure and Microhardness of CuCrFeMnNi High-Entropy Alloy

This study investigated four cooling methods for CuCrFeMnNi high-entropy alloy, namely, furnace cooling, air cooling, oil cooling, and water cooling (designated as FC, AC, OC, and WC, respectively), following a 12 h treatment at 800 °C. Results indicate that all four cooled alloys consisted of two FCC solid-solution phases (FCC1 and FCC2) and ρ phases. However, the FC alloy primarily contained FCC2 as the main phase and FCC1 as the secondary phase. The other three cooling methods yielded alloys with FCC2 as the primary phase and FCC1 as the secondary phase. With an increase in cooling rate, the content of the FCC1 phase gradually increased, that of the ρ phase initially decreased and then increased, and that of the FCC2 phase gradually decreased. The microstructure of the CuCrFeMnNi high-entropy alloy under the four cooling methods consisted of gray-black dendrites rich in Cr-Fe and white dendrites rich in Cu. Black ρ-phase particles predominated the dendrite region. As the cooling rate increased, the white interdendritic regions shrank, and the gray-black interdendritic regions expanded. The FC alloy exhibited the lowest microhardness at approximately 202.6 HV. As the cooling rate increased, the microhardness of the alloy progressively increased. The microhardness of the WC alloy was the highest, at approximately 355 HV. The strengthening mechanisms for all the alloys were primarily solid-solution strengthening and second-phase precipitation strengthening.

Technology development of novel autogenous double pulse tungsten insert gas welding technique to evaluate the depth of penetration, micro segregation via machine learning and desirability function approach

The present research investigates the effect of process parameters on the microstructure, micro segregation, and material properties of the Autogenous Double Pulse Tungsten Inert Gas Welding (ADP-TIG) of Inconel 625. The optimization of the process parameter was evaluated by Response surface Methodology (RSM) Box Behnken method. In this article, the effects of the weld-bead geometry, weld centre (WC), weld interface (WI), and heat affected zone (HAZ) were evaluated through macro morphology, microstructure, SEM/EDAX, XRD, and micro hardness. The outcomes indicate that by employing a combination of high and low frequency pulsing in ADP-TIG, it is possible to regulate not only the dimensions of the weld-bead and penetration depth but also the HAZ. The ADP-TIG process has a low heat input, resulting in finer grains in the microstructure, reduced secondary phases, and a narrower HAZ. SEM images of alloy 625 confirms the depiction of fine equiaxed dendrites. The ADP-TIG process reduces secondary phase formation due to a reduction in Mo and Nb alloying elements. EDAX results also show that the micro segregation in the weld centre (WC) and weld interface (WI) is very less in the dendritic core region because of the lower heat Input. The XRD result confirms the presence of NbzNi, Cr₂Nb, Ni8Nb, Fe2Mo3 and FeNi phases. The maximum microhardness values in WC and WI are 290 HV and 280 HV, respectively. The impacts of ADP-TIG welding technique specifications on factors such as weld bead geometry, WC, WI, and HAZ have been thoroughly examined across a range of process parameters. Further the process parameters of ADP-TIG were optimized using a desirability function to achieve defect-free welds, followed by experimental validation. The desirability function results were then compared with a machine learning (ML) approach. The investigation aimed to assess ML algorithms' predictive capability for weldment outcomes. From the ML modelling results, Support Vector Machine (SVM) using the Radial Basis Function (RBF) kernel was identified as the superior strategy for accurately predicting Heat input, Mo segregation, and Nb segregation. Additionally, Gaussian process regression (GPR) with an RBF kernel was recommended for predicting the Width to Depth Ratio.