Excessive Melting Research Articles

Unveiling the devastating effect of the spring 2022 mega-heatwave on the South Asian snowpack

Global warming has led to a notable increase in heatwaves globally and regionally. In spring 2022, South Asia witnessed an unprecedented heatwave with temperatures breaking historical records and exceeding 5° C from climatological mean at several locations in the northern Indian subcontinent. Here, using 3D tracking, this heatwave ranked the most severe in the past 64 years, characterized by its protracted duration and wide spatial extent. The excess atmospheric heat, represented by temperature anomalies, during the mega-heatwave triggered rapid snowmelt across the snow-covered areas in the region, leading to an average loss of 42% in snow cover and 57% in snow depth of the regional snowpack. This rapid melting resulted in the complete disappearance of low-level snowpack in the western Himalayas, Pir Panjal, and Afghanistan highlands, leading to the lowest snowpack observed in the last six decades. Moreover, during the heatwave, the amount of snowfall received was only 29% of the long-term average. This combination of excessive melting and reduced snowfall culminated in a severe regional snow drought in spring 2022. The heatwave genesis lay a persistent high-pressure system over Northwest South Asia, reinforced by a quasi-stationary Rossby wave packet over Europe during the initial spell. Continuous heat from high-pressure ridges associated with circumglobal Rossby waves combined with the physical barrier of the Himalayas, lent staying power to this system during the second phase.

Effect of Preheating Parameters on Extrusion Welding of High-Density Polyethylene Materials.

High-density polyethylene (HDPE) has emerged as a promising alternative to fiber-reinforced plastic (FRP) for small vessel manufacturing due to its durability, chemical resistance, lightweight properties, and recyclability. However, while thermoplastic polymers like HDPE have been extensively used in gas and water pipelines, their application in large, complex marine structures remains underexplored, particularly in terms of joining methods. Existing techniques, such as ultrasonic welding, laser welding, and friction stir welding, are unsuitable for large-scale HDPE components, where extrusion welding is more viable. This study focuses on evaluating the impact of key process parameters, such as the preheating temperature, hot air movement speed, and nozzle distance, on the welding performance of HDPE. By analyzing the influence of these variables on heat distribution during the extrusion welding process, we aim to conduct basic research to derive optimal conditions for achieving strong and reliable joints. The results highlight the critical importance of a uniform temperature distribution in preventing defects such as excessive melting or thermal degradation, which could compromise weld integrity. This research provides valuable insights into improving HDPE joining techniques, contributing to its broader adoption in the marine and manufacturing industries.

A century of variability of heatwave-driven streamflow in melt-driven basins and implications under climate change

Abstract Meltwater runoff from snow and glaciers in high mountain regions supports the water needs of hundreds of millions of people, but extreme events such as heatwaves modify the timing and magnitude of water available for downstream communities and ecosystems. The streamflow response to heatwaves depends strongly on heatwave timing and temperature, and the amount of snow and glacier ice available to melt. However, as ongoing climate change continues to alter both seasonal melt patterns and the frequency and intensity of heatwaves, it is not well understood how such streamflow responses will evolve relative to the seasonal cycle of streamflow. We address this knowledge gap by using long-term meteorological and hydrological datasets to characterize spatial and temporal heterogeneity in the streamflow sensitivity to heatwaves at six basins with >80 years of observations in Western Canada. We use years with earlier freshets and less snowfall as proxies of anticipated climate change, and apply a metric to describe how the streamflow sensitivity to heatwaves varies across years with different hydro-climatological characteristics. We find that in future proxy years relative to baseline years, nival streamflow is more sensitive to early spring heatwaves but less sensitive to late spring and summer heatwaves. Relative to baseline years, late spring heatwaves in future proxy years generate a smaller fraction of peak streamflow that is diminished as the freshet progresses. Our findings imply that future heatwave-driven peak flows in spring may be lessened by the diminished streamflow sensitivity to heatwaves in late spring, but this may be partially offset by excess melt during future heatwaves that are longer and hotter.

Experimental investigation of nanosecond pulsed laser ablation of polycrystalline diamond composite

A fundamental understanding of the laser ablation of polycrystalline diamond composite (PCD) at different laser energy intensities is indispensable for extending these findings to practical applications where, through appropriate parameter combinations, a substantial amount of material with minimal thermal damage should be removed. The objective of this study is to investigate experimentally the nanosecond ablation of polycrystalline diamond composite at different laser pulse energies and input energy densities. The research comprised two distinct categories of experiments: (1) single-point and (2) line experiments. In single-point tests, the number of the incidence pulses (N.P) was varied from 1 to 100 pulses with different pulse energies (Ep) ranging from 40 to 200 µJ. As the N.Ps increased, the ablation depth increased as well. No considerable enhancement in ablation depth was observed with the increase in pulse energies. For the line experiments, the results emphasized the differences in ablation depths by nearly a factor of 2, resulting in a corresponding change in laser input densities from 6.5 J/mm2 to 1.3 J/mm2. The ablation difference was pronounced as the number of repeats of the scanning path increased. The results emphasize that the ablation depth varies at the same pulse energy when the pulse overlap decreased from 100 % to lower percentages. Based on these results, a constant laser energy density with three different combinations of laser inputs—namely, scanning speed and average power—was selected to evaluate the ablation depth and quality. The results show that in moderate numbers of scan repeats (here 20, 30 & 40 times), it is advisable to adopt a minimum pulse energy when the same ablation depth is achieved compared to higher pulse energies. The ablation pile-up was also evaluated in these repeat ranges, indicating that higher pulse energies and repeats do not result in ablation improvement and cause excessive melt deposition.

Effect of VC content on the microstructure, ablation and oxidation resistance of the protective oxide layer of C/C-ZrC-VC-SiC composites

A third reinforcement vanadium carbide (VC) is introduced to improve the compactness, ablation and oxidation resistance of the protective oxide layer of C/C-ZrC-SiC composites, and the effect of VC content on the microstructure and properties of the oxide layer is studied. Results showed that the compactness of the oxide layer gradually increased with the increase of VC content. Excessive oxide melt leaded to an increase in the evaporation and mechanical erosion. Z2V1S6 exhibited the best ablation and oxidation resistance, which was attributed to the formation of a tightly bound composite oxide bi-layer with a dense ZrO2-SiO2-V2O3 inner layer and a ZrO2 skeleton outer layer bonded by SiO2-V2O3 melt.

Optimization Method of Sheet Metal Laser Cutting Process Parameters under Heat Influence

To address the issues of workpiece distortion and excessive material melting caused by heat accumulation during laser cutting of thin-walled sheet metal components, this paper proposes a segmented optimization method for process parameters in sheet metal laser cutting considering thermal effects. The method focuses on predetermined perforation points and machining paths. Firstly, an innovative temperature prediction model Tpr,t is established for the nth perforation point during the cutting process, with a prediction error of less than 10%. Secondly, using the PSO-BP-constructed prediction model for laser cutting quality features and an empirical model for processing efficiency features, a multi-objective model for quality and efficiency is generated. The NSGA II algorithm is employed to solve the objective optimization model and obtain the Pareto front. Next, based on the predicted temperature at the perforation point using the model Tpr,t, the TOPSIS decision-making method is applied. Different weights for quality and efficiency are set during the cutting stages where the temperature is below the lower threshold and above the upper threshold. Various combinations of machining parameters are selected, and by switching the parameters during the cutting process, the thermal accumulation (i.e., temperature) during processing is controlled within a given range. Finally, the effectiveness of the proposed approach is verified through actual machining experiments.

Process Parameters of High Frequency Welding.

High frequency (HF) welding of polymer materials is increasingly used in modern manufacturing processes. The literature on HF welding process parameters was reviewed and it was found that 3-5 basic welding parameters were considered, which is insufficient for the scientific study of HF welding of polymeric materials. This article presents the mathematical expressions for the evaluation combining 17 influential parameters. For the first time, the specific and latent heat of the welded polymer material were used. The breaking forces of welds made by RF welding are investigated by varying the anode current, the coupling capacitor, and the exposure time of the HF electromagnetic fields. It was found that the amount of HF energy supplied depends on the breaking forces of the weld. A characteristic inflection point was also observed in the graph of the dependence of the breaking forces on the percentage of the coupling capacitor and the anode current. During elongation, it was observed that the weld is separated by peeling before the inflection point and breaks after the inflection point by tearing at the extruded edges of the weld. If the HF energy is applied to the weld for too long, there will be excessive melting of the material in the weld, thinning of the weld, unfavourable appearance of the extruded edges and electrical breakdown, and a drastic drop in the breaking force.

Improved strength in nickel‑aluminum bronze/steel bimetallic component fabricated using arcing-wire arc additive manufacturing with alternating deposition strategy

To enhance microstructure and mechanical properties, arcing-wire arc additive manufacturing (AWAAM) with alternating deposition strategy was firstly employed to produce nickel‑aluminum bronze (NAB)-steel components. The implementation of alternating deposition strategy fostered the creation of interlocked microstructures, establishing robust bonds at the interface. Moreover, the convection within the melt pool during alternating deposition induced the formation of numerous precipitates, serving as a precipitation reinforcement. Simultaneously, these precipitates served as heterogeneous nucleation sites, facilitating the formation of substantial fine equiaxed crystals, resulting in grain boundary strengthening. A comprehensive examination of microstructure and mechanical properties was conducted using a variety of microscopy techniques and mechanical testing for components with and without arcing-wire. After applying arcing-wire, precise control was exerted over the melting of both matrix and wire, effectively preventing interface cracking caused by excessive melting. Moreover, with the arc heat input diminished, the temperature gradient in the melt pool decreased, leading to grain and precipitate refinement, consequently enhancing their strength. Owing to microstructural modifications, AWAAM demonstrated enhancements in ultimate tensile strength and yield strength by up to 20.1 % and 21.1 %, respectively, when compared to WAAM.

Overture for the Mandara and Vasuki Plates

Models of past plate motions in the Indian Ocean help map the supercontinent Gondwana and investigate how mantle plumes influence plate tectonics. Reducing confidence in this, however, the range of available models all produce large pre-94 Ma movements, in various kinematic senses, between India and Madagascar. There is no observational evidence for any of these motions, suggesting along with their diversity that they are artefacts stemming from contrasting resolutions of techniques used for reconstructing India and Madagascar to Antarctica. A higher resolution approach to India–Antarctica reconstruction concentrates on geophysical records of relative plate motion azimuths. Applying its results regionally eliminates Indo-Malagasy motions before 94 Ma, and prompts new hypotheses of two small tectonic plates. The early Cretaceous Mandara plate, in the Enderby Basin off East Antarctica, may have initiated and rotated at a mid-ocean ridge that was supplied by excess melt from the Kerguelen plume. The late Cretaceous Vasuki plate may have conveyed Sri Lanka southwards across the western Bay of Bengal. The 85°E and Comorin ridges may have formed at active transform fault zones along Vasuki’s margins that were supplied with excess melt from the Crozet and Marion plumes. The model confidently implies the presence of 500,000 km2 of continental crust beneath the Kerguelen Plateau, places Sri Lanka 1000 km further east within Gondwana than previous reconstructions, and casts doubt on the existence of plate kinematic signals that have previously been attributed to the arrival and spread of the Marion plume beneath India and Madagascar at ~105 Ma.

AMMONIUM-SALT METHODS ARE THE BASIS FOR BUILDING EFFECTIVE NEW TECHNOLOGIES IN CHEMICAL AND METALLURGY INDUSTRIES

The article contains new data, which is a continuation of the research for the development of scientific theoretical applied directions, which appeared in previous publications related to the field of chemical technologies and metallurgy. Previous studies have used ammonium salts as reagents for the production of synthetic sodium carbonate and fluorides, but this publication shows the possibilities of using them for the development of non-ferrous metallurgy. The purpose of the work is to show the importance of the anionic hydrogen atom contained in ammonium bisulfate (ABS) in entering the compound. Thermodynamic, thermal, renggenphase analysis and mathematical programs were used in the research methods. Physical and chemical changes in reaction mixtures, some synthesized salts when heated using the system derrivatograph Q-1000/D of the company" mom " F.Paylik, J. Paylik, L. Erdey and LabSys Evo were studied using special standardized factory structures such as TG-DTA/DSC (Setaram, France). The probability of some reactions occurring or not occurring was thermodynamically evaluated using the HCs-5.1 Chemistry (Outokumpu) "Astra-4" software package (complex). In the results of the study, the method of processing raw materials of non-ferrousmetals is presented in the form of a basic technological scheme.The possibility of formation of intermediate complex Tutton salts during production of the final product and reactions leading to their decomposition has been shown by thermodynamic studies. It is shown that the decomposition of such ammonium nickel sulfate salt releases ammonia into the melt of crystalline metal sulfate and ammonium bisulfate at about 235-260°С, where the pyrolysis of ammonium sulfate begins. It was observed that the by-products of (NH4)2Ni(SO4)2nickel ammonium Tutton's salt heated in the ABS melt up to 300-350°C are nickel sulfate and ABS melt, and ammonia also reacts upon re-cooling. It was experimentally determined that this "heating-cooling" process changes the color of ABS melt from lemon yellow to white. During the repetition of the process, it was found that this phenomenon is repeated until the excess melt is exhausted. This phenomenon is explained by the formation of nickel acid salt between nickel sulfate and ABS melt, which no one has studied before. It was concluded that this phenomenon should be common to ABS melt with sulfate of other metals.

Crack-free tungsten coating on ODS plate via a modified laser-based additive technique: Offset laser cladding

A modified laser-based additive manufacturing technique, offset laser cladding was introduced to achieve dense tungsten coating on an oxide dispersion-strengthened (ODS) substrate as a plasma facing material (PFM). Different from ordinary direct energy deposition (DED) which leads to incomplete melting of tungsten and excessive melting of ODS substrate, the offset laser cladding technique can achieve complete melting of tungsten while substrate melting is suppressed. Experimental conditions (i.e., laser power, scanning speed, powder size, offset distance and injection powder nozzle setting) were carefully calculated using two validated simulation models to minimize the consumption of valuable experimental resources. Tungsten coating using the offset laser cladding in an open chamber condition showed that dense coating was achieved with a pore size of 1–2 μm. The result is comparable to that of vacuum plasma spray (VPS) tungsten coating which requires a high-level vacuum chamber. A thin interface layer (2–5 μm) was formed between the tungsten coating and ODS substrate that can alleviate thermal damage due to a large thermal expansion coefficient difference. While a small amount of surface melting was involved, the microhardness test revealed that the ODS substrate was insignificantly affected by laser heating during the offset laser cladding.

A Scaling Relation for Cryoconite Holes

AbstractTiny cryoconite holes are commonly found on glacier surfaces. Despite a long history of research on them, their influence on glacier‐scale mass balance and runoff are not well understood. We model the absorption of solar radiation at the bottom of cylindrical cryoconite holes, incorporating the three‐dimensional geometry. The simulated holes achieve a limiting steady‐state depth, where the daily melt rate at the bottom of the holes matches that at the glacier surface. This implies a feedback loop restricting the excess ice melt due to the presence of dark supraglacial impurities. The modeled steady‐state depth scales approximately linearly with the radius, consistent with in situ observations at several glaciers across the world. Given the areal coverage and radius distribution of cryoconite holes on a glacier, this scaling yields first‐order estimates of their melt contribution.

Spatiotemporal variability in ocean-driven basal melting of cold-water cavity ice shelf in Terra Nova Bay, East Antarctica: roles of tide and cavity geometry

Mass loss from ice shelves occurs through ocean-driven melting regulated by dynamic and thermodynamic processes in sub-ice shelf cavities. However, the understanding of these oceanic processes is quite limited because of the scant observations under ice shelves. Here, a regional coupled sea-ice/ocean model that includes physical interactions between the ocean and the ice shelf is used as an alternative tool for exploring ocean-driven melting beneath the Nansen Ice Shelf (NIS) which is a cold-water cavity ice shelf located beside Terra Nova Bay (TNB) in East Antarctica. For the first time, this study identifies the spatiotemporal variability signatures for different modes of ocean-driven melting at the base of NIS. In February (austral summer), basal melting substantially increases where the ice shelf draft is relatively small in the vicinity of the ice shelf front, contributing 78% of the total NIS melting rate. As the dominant source of NIS mass loss, this melting is driven by tide-induced turbulent mixing along the sloping ice shelf base and summer warm surface water intruding beneath and reaching the shallow parts of the ice shelf. In contrast, the NIS has relatively high basal melting rates near the grounding line in September (austral winter) primarily because of the intrusion of high-salinity shelf water produced by polynya activity in TNB that flows into the cavity beneath NIS toward the deep grounding line. Of the total melting rate of NIS in winter, 36% comes from regions near the grounding line. In addition, the contributions of tides and realistic cavity geometry to NIS basal melting are identified by conducting sensitivity experiments. Tidal effects increase the melting of NIS throughout the year, particularly contributing as much as 30% to the areas of ice draft shallower than 200 m in summer. Sensitivity results for uncertainty in cavity geometry show that spurious vertical mixing can be locally induced and enhanced by interaction between tides and the unrealistic topography, resulting in excessive basal melting near the NIS frontal band. The sensitivity experiments have shown that tides and realistic cavity geometry bring a significant improvement in the estimation of basal melt rates through a numerical model.

A bifunctional kinase-phosphatase module balances mitotic checkpoint strength and kinetochore-microtubule attachment stability.

Two major mechanisms safeguard genome stability during mitosis: the mitotic checkpoint delays mitosis until all chromosomes have attached to microtubules, and the kinetochore-microtubule error-correction pathway keeps this attachment process free from errors. We demonstrate here that the optimal strength and dynamics of these processes are set by a kinase-phosphatase pair (PLK1-PP2A) that engage in negative feedback from adjacent phospho-binding motifs on the BUB complex. Uncoupling this feedback to skew the balance towards PLK1 produces a strong checkpoint, hypostable microtubule attachments and mitotic delays. Conversely, skewing the balance towards PP2A causes a weak checkpoint, hyperstable microtubule attachments and chromosome segregation errors. These phenotypes are associated with altered BUB complex recruitment to KNL1-MELT motifs, implicating PLK1-PP2A in controlling auto-amplification of MELT phosphorylation. In support, KNL1-BUB disassembly becomes contingent on PLK1 inhibition when KNL1 is engineered to contain excess MELT motifs. This elevates BUB-PLK1/PP2A complex levels on metaphase kinetochores, stabilises kinetochore-microtubule attachments, induces chromosome segregation defects and prevents KNL1-BUB disassembly at anaphase. Together, these data demonstrate how a bifunctional PLK1/PP2A module has evolved together with the MELT motifs to optimise BUB complex dynamics and ensure accurate chromosome segregation.

Knowledge and Adaptation Practices: Baseline Data for the Development of Climate Change Engagement Model

Climate change (CC) will continue to harm the environment if mitigation efforts are slow. Raising the CC knowledge and awareness of individuals is crucial in prompting significant mitigating action or adaptation practices. In addition, empowering young people will potentially ignite more innovative strategies that are helpful in decelerating the impacts of CC. The study aimed to determine students’ knowledge of CC and their adaptive practices. Based on the findings, a model to engage students in CC action was developed. The respondents were 132 students in a State University in Region III enrolled in AY 2022-2023. Data were gathered using a validated self-made questionnaire. Findings revealed that while most respondents were knowledgeable of the concept of climate change (62.88%), a sizable percentage were still misinformed. In addition, the respondents knew the causes of CC such as the emission of greenhouse gases (87.12%), deforestation (57.58%), and excessive fertilizer use (37.88%) but some causes of climate change were unknown to them. Moreover, most of them were cognizant of the consequences of climate change which include excessive rain (96.21%), flood (95.45%), and melting of snow (94.70%). But the response to “drought” as one of the consequences of climate change was only known to a few students (47.73%). As to the knowledge of the health effects of climate change, most students knew CC raises respiratory, water-borne, and skin diseases but some expressed their lack of knowledge about other diseases such as the possibility of triggering cancer and mental health issues. Moreover, students have developed CC adaptive practices such as consuming more fruits and vegetables than meat and conserving energy use at home, but they were observed to be inconsistent in some areas such as in practicing the 3Rs and in throwing away less food. The F-value of 0.021 and 0.82 p-value, to compare the CC adaptive practices of the respondents with respect to gender, support the acceptance of the null hypothesis. Gender is not a determinant of CC adaptive practices. This indicates that gender is not a barrier to CC action. The study concludes that students have limited knowledge about climate change, especially on the health impacts. Also, the students’ CC adaptive practices imply lack of commitment to act on CC. The study recommends strengthening the integration of climate change into school policies, research, extension, and instruction and a strong support of school stakeholders in their implementation. A climate change engagement model is an output of this study which may be considered by schools in prompting students to participate in CC action. A future study may include the factors that hinder students’ consistent involvement in CC action despite their awareness and knowledge about the negative consequences.

Critical effect of heat input on joint quality in resistance element welding of Al and steel

Resistance element welding (REW) has recently attracted increasing interest, especially in the joining of high-strength steels and aluminum alloys. However, the intensity of heat input is a critical factor for the joint quality due to the possibility of excessive melting of the aluminum sheet around the element shank, which often degrades the joint's performance. This study evaluates the influence of heat input on the joint formation and mechanical performance of REW joints between ultra-high strength steel and aluminum alloy. In addition to the experimental investigations, a finite element method (FEM) was used to analyze the temperature distribution, nugget formation, and aluminum sheet melting characteristics as a function of heat input. The results show that the nugget dominates the joint's strength if the heat input is comparatively low. When heat is increased, however, the aluminum sheet plays a significant role in the joint's strength. Excessive melting of aluminum sheets reduces the load-bearing area of the joint. The competition between the weld nugget and aluminum sheet determines the joint's strength. The failure mode changes from interfacial to aluminum sheet failure as the heat input increases. The combined effect of aluminum sheet thickness and heat input on the joint strength was also evaluated. The results indicate that determining the appropriate heat input level is crucial to achieving an excellent performance of the REW joints.

Improving the mechanical properties of 3D printed recycled polypropylene‐based composites through adjusting printing temperature

AbstractThis work aimed at investigating the effects of recycling on the mechanical properties of recycled polypropylene (PP)‐based composites and improving the mechanical properties of recycled materials by adjusting the remanufacturing temperature. In this study, 3D printing was selected as the remanufacturing approach and the composites were ground and reextruded up to nine times to simulate mechanical recycling. The gel permeation chromatography results indicated that the recycling led to a reduction in molecular weight, increasing the melt fluidity of the materials. Excessive melt flow of material during printing caused the poor quality of printed parts with macro and micro defects, deteriorating the mechanical properties of the printed specimens. To improve the final quality and mechanical properties of the printed specimens, melt flow during the printing of recycled materials was adjusted by tuning the printing temperature. The results found that the mechanical properties of the recycled PP‐based composites were well enhanced by using tuned printing temperature.

Assessment of Runoff Components of River Flow in the Karakoram Mountains, Pakistan, during 1995–2010

Glaciers are generally believed to be subjugating by global warming but the Karakoram glaciers are reportedly maintaining their balance. Earlier studies in the Karakoram and its sub-basins have mostly addressed a short span of time and used complex models to understand the phenomenon. Thus, this study is based on a long-term trend analysis of the computed runoff components using satellite data with continuous spatial and temporal coverage incorporated into a simple degree day Snowmelt Runoff Model (SRM). The trends of melt runoff components can help us understanding the future scenarios of the glaciers in the study area. The SRM was calibrated against the recorded river flows in the Hunza River Basin (HRB). Our simulations showed that runoff contribution from rain, snow, and glaciers are 14.4%, 34.2%, and 51.4%, respectively during 1995–2010. The melting during the summer has slightly increased, suggesting overall but modest glacier mass loss which consistent with a few recent studies. The annual stream flows showed a rising trend during the 1995–2010 period, while, rainfall and temperatures showed contrasting increasing/decreasing behavior in the July, August, and September months during the same period. The average decreasing temperatures (0.08 °C per annum) in July, August, and September makes it challenging and unclear to explain the reason for this rising trend of runoff but a rise in precipitation in the same months affirms the rise in basin flows. At times, the warmer rainwater over the snow and glacier surfaces also contributed to excessive melting. Moreover, the uncertainties in the recorded hydrological, meteorological, and remote sensing data due to low temporal and spatial resolution also portrayed contrasting results. Gradual climate change in the HRB can affect river flows in the near future, requiring effective water resource management to mitigate any adverse impacts. This study shows that assessment of long-term runoff components can be a good alternative to detect changes in melting glaciers with minimal field observations.

A molecular dynamics simulation-based laser melting behavior analysis for Ti–Al binary alloy

Due to the lack of theoretical basis for the determination of process parameters, there are problems such as incomplete melting and excessive melting in the molten pool for laser processing, which ultimately cause the increase of defects such as air hole and crack. The melting behavior of Ti–Al binary alloy during laser processing is studied on the atomic scale by molecular dynamics simulation. The embedded atom method potential is adopted to establish the melting model of Ti–Al binary alloy. According to the changes of temperature, atomic structure and mean square displacement, the influence of different process parameters on the melting behavior of Ti–Al binary alloy is discussed. The results show that a short temperature drops from initial melting to complete melting. Mean square displacement increases rapidly with the increase of laser time after completely melting. The atoms start to move violently and the atomic structure is completely transformed into other structure. The heating and cooling rate increases with the increase of power. The laser power has little effect on the overall distribution of atoms after completely melting and only affects the variation rate of various physical quantities in melting process. The research results provide a deeper practical and theoretical evidence for the determination and optimization of the 3D printing and laser heat treatment.

Copper plating on bonding properties of aluminium/steel explosive welded composite plate

In order to reduce critical impact velocity and enlarge weldability window of aluminium/steel explosive welding, a chemical copper plating layer as interlayer was proposed to carry out aluminium/steel explosive welding. The results showed that the interface of the 1060/Q235 composite plate had good bonding performance, and no obvious defects such as cracks and pores were found. Copper plating as intermediate layer could enlarge aluminium/steel weldability window. The thickness of solidified melt was much thicker than that of diffusion zone. The molten copper particles participated in the formation of re-entry jet, which rotated under the action of initial jet. The presence of the Cu layer reduces the occurrence of excessive melting during welding and improves the properties of the interface.