Thermal Conductivity Of Bulk Materials Research Articles

Investigation of thermal contact conductance of bare copper-copper and aluminum 1070-aluminum 1070 interfaces at low temperatures between 10 and 70 K

The prediction model of thermal contact conductance (TCC) for bare OFHC-OFHC and Al 1070-Al 1070 flat interfaces is presented. OFHC (Oxygen free high conductivity copper) and Aluminum are widely used in cryogenic systems. Since the thermal conductivity of pure copper or aluminum materials has a highly non-linear characteristic with its peak value at around 20 K, it is difficult to predict TCC of those materials at this temperature range. The TCC model in this paper proposes the dimensionless correlation through 16 experiments considering various conditions such as surface roughness, materials, pressure, and temperature. The model has been established by the modification on the previous CMY (Cooper, Mikic, Yovanovich) model with additional parameters. The first important feature of the model is to adopt the contact thermal conductivity (kc). It can be calculated by using the size effect theory at the micro-scale contact single spot. The second feature is the dimensionless temperature (T/TD). An experimental setup is constructed inside of the conduction-cooled cryostat to measure the thermal conductivity of bulk material and the TCC simultaneously for the temperature range between 10 K and 70 K. OFHC and Al 1070 specimens with various surface roughness are prepared and tested with contact pressure of 6 to 13.5 MPa in vacuum environment. The predicted TCC by the proposed model shows a reasonable agreement with the experimental results in low temperature.

Examination of thermophysical characteristics of food products

The development of food, biotechnological, and processing industries, the invention of new ingredients, optimisation and improvement of technological processes require reliable information about the main thermophysical characteristics of raw materials and materials of biological origin. This paper presents the results of the cooperation of specialists from leading universities and scientific institutions of Ukraine, embodied in the developed methods of analysing the parameters of thermodynamic and mass transfer processes and determining the thermophysical characteristics of the latest substances and products using modern metrologically certified devices and information-measurement systems. The main problem in analysing materials of biological origin is the inhomogeneity and heterogeneity of the structure of samples. It is demonstrated that it is advisable to determine the coefficient of effective thermal conductivity of bulk materials and cereals in a stationary thermal mode on a device for determining the thermophysical characteristics of materials and thermal effects, equipped with heat flow and temperature sensors, in which a symmetric scheme of the thermometric measurement method is implemented. The simultaneous use of four measuring cells allows for performing a synchronous comparative analysis of several samples, and the rotary-clamping mechanism helps to minimise contact resistances. The developed method of measuring the coefficient of effective thermal conductivity considers the features of bulk food products and substantially improves the accuracy of the examination by introducing a correction for the contact resistance of the wall layer. Long-term observations allow for analysing thermolabile materials, examining thermal effects in samples, and evaluating volumetric and integral heat generation. It is necessary to use the STA system to conduct calorimetric studies of a wide range of biological materials and substances with the necessary accuracy, which implements methods of step-by-step scanning and synchronous thermal analysis to determine the specific heat capacity, the heat of evaporation, and the ratio of free and bound moisture in nonhomogenous materials. These characteristics are necessary parameters for analysing the kinetics and optimisation of heat and mass transfer processes, in particular, drying, in the calculation and design of technological equipment

Thermal rectification enhancement based on porous structure in bulk materials

Thermal rectification effect refers to an asymmetric heat transfer phenomenon (namely, the amount of heat flux depends on the direction of temperature gradient). A two-segment bar made of two materials that have thermal conductivities with different temperature-dependence, can realize the thermal rectification effect. In the present paper, we propose to use porous structure on the bulk material to modify the thermal conductivity of bulk material. It is found that the thermal rectification effect can be enhanced by the porous structure. The finite element method and effective medium approximation are used to analyze the influence of porosity on the thermal rectification ratio of the two-segment system. The calculation results are consistent with each other. Under low temperature bias, the effect of the porosity is weak, while its influence becomes very significant when the temperature difference is high. Usually, thermal rectification ratio decreases if the porous structure is made on the segment whose thermal conductivity increases with temperature increasing. If the porous structure is made on the segment with negative temperature-dependent thermal conductivity, an optimal porosity can be found. For low porosity, the forward heat flux keeps almost unchanged while the reverse heat flux decreases by more than half, and the thermal rectification ratio can be increased to twice or more than thrice that in the case of no porous structure. For a fixed temperature difference, the influence of porosity on the thermal rectification ratio increases with the augment of the power exponent value.

INFLUENCE OF FILLER QUALITY ON CONCRETE THERMAL CONDUCTIVITY

Studies on the effect of grain composition on the thermal conductivity of lightweight concrete, it was shown that the mineral composition of filler (aggregates) substantially reflects the thermal conductivity and density of concrete. The grains of the component have a slightly higher effect on the thermal conductivity than the material itself. The proof of this position is that the thermal conductivity of bulk materials is always slightly lower than cellular materials of the same average density. In an absolutely dry porous body, heat transfer can occur not only through thermal conductivity but also through the solid skeleton of the body, located in the air pores, but also by convection and radiation between the pore walls. With a pore diameter of less than 1 mm, convective heat transfer is practically zero, and the coefficient of radiant heat conductivity can be neglected only when the pore diameter is less than 0.5 mm. Therefore, with the same porosity, the thermal conductivity coefficient will be the greater, the larger the pores of the material. Therefore, the creation of a finely porous structure of lightweight concrete and the use of finely porous aggregates contributes to the production of concrete with reduced thermal conductivity. The proof can be the results of experiments and the curves presented. An increase in the pore size on the surface of the grains of the aggregates leads to an increase in intergranular voids of the mixtures. As a result of mineralogical-petrographic studies of artificial porous aggregates, it was established that aluminosilicate phases with a disordered structure — clay amorphized with firing and acidic glasses — predominate in expanded clay, agloporite, and expanded perlite. Slag is characterized by a predominance of crystalline phases - low-basic calcium silicates than calcium and magnesium aluminosilicates. The glassy phase is present only in the form of an impurity of 15 - 20%. When analyzing the experimental data, we came to the conclusion that the thermal conductivity of expanded clay increases with increasing density. However, at the same density, expanded clay of different batches of the same plant and especially of different plants, differ in the values of the coefficient of thermal conductivity.

Thermal conductivity of Nylon 46, Nylon 66 and Nylon 610 characterized by Flash DSC measurement

We recently developed Flash DSC application to characterize the cross-plane thermal conductivity of polyethylene thin films (Thermochimica Acta 2019, 677, 21–25). We hereby applied this method to measure the thermal conductivities of Nylon 46, Nylon 66 and Nylon 610 after their complete crystallization at 156.6 °C, i.e. the temperature around the melting points of Indium particles. The melting point differences of two Indium particles separately placed on the top of the Nylon samples and on the reference cell exhibit a linear dependence of the heating rates, demonstrating the Fourier’s heat conduction law. From the slope, we further derived the thermal conductivity after we measured the specific heat capacity via conventional DSC and measured the sample thickness via the laser confocal fluorescence microscope. The obtained thermal conductivities of three Nylon samples increase with their hydrogen-bonding densities, which are consistent with conventional experimental approaches. The observations validated the general application of our method for the measurement of thermal conductivity of bulk materials.

Simulation and prediction on phonon thermal conductivity of Al/Cu interface

Based on the non-equilibrium molecular dynamics (NEMD) method, phonon thermal conductivity of Al/Cu interfaces is systematically studied by considering the temperature dependence and size effect of thickness under different temperatures, for which an approximate mathematical model is also proposed. In this model, phonon thermal conductivity can be described by the thermal conductivities of Al and Cu thin materials according to the electrical thermal transport and the free electron approximation theories. Meanwhile, the thermal conductivities of each thin films can be described using the thermal conductivities of each bulk materials due to the Wiedemann-Franz Law under the thin thickness (less than the mean free path) and below the recrystallization temperature. The results show that the contribution of Al and Cu is inversely proportional to the interface thermal conductivity. This investigation based on the thermal and electronic conductivity of bulk materials, is helpful for understanding the interface heat transfer mechanism of interface structures, which also implies a potential method for the analysis of thermal performance of interfaces and design of interface structures.

Thermal Transport in Nanoporous Yttria-Stabilized Zirconia by Molecular Dynamics Simulation

Yttria-stabilized zirconia (YSZ) is widely used as thermal barrier coatings (TBCs) to reduce heat transfer between hot gases and metallic components in gas-turbine engines. Porous structure can generally reduce the lattice thermal conductivity of bulk material, so porous YSZ can be potentially used as TBCs with better thermal performance. In this work, we investigate the thermal conductivity of nanoporous YSZ using the nonequilibrium molecular dynamics (NEMD) simulation, and comprehensively discuss the effects of cross-sectional area, pore size, structure length, porosity, Y2O3 concentration and temperature on the thermal conductivity. To compare with the results of the NEMD simulation, we solve the heat diffusion equation and the gray Boltzmann transport equation (BTE) to calculate the thermal conductivity of the same porous structure. From the results, we find that the thermal conductivity of YSZ has a weak dependence on the structure length at the length range from 10 to 26 nm, which indicates that the majority of heat carriers have very short mean free path (MFP) but there exists small percentage (about 3%) of phonons with longer MFP (larger than 10 nm) contributing to the thermal conductivity. The thermal conductivity predicted by NEMD simulation is smaller than that of solving heat diffusion equation (diffusive limit) with the same porous structure. It shows that the presence of pores affects phonon scattering and further affects the thermal conductivity of nanoporous YSZ. The results agree well with the solution of gray BTE with a average MFP of 0.6 nm. The thermal conductivity of nanoporous YSZ weakly depends on the Y2O3 concentration and temperature, which shows the phonons with very short MFP play the major contribution to the thermal conductivity. The results help to better understand the heat transfer in porous YSZ structure and develop better TBCs.

Simultaneous measurement of in-plane and through-plane thermal conductivity using beam-offset frequency domain thermoreflectance.

Transient thermoreflectance (TTR) techniques are ubiquitous methods for measuring thermal conductivity of bulk materials and thin-films. Both through-plane thermal conductivity k⊥ and in-plane thermal conductivity k∥ should be independently measured in transversely anisotropic materials. When these properties are measured using conventional TTR techniques, the accuracy of the k∥ measurement is dependent on the accuracy of measuring k⊥ and vice versa. This is especially problematic for thin-films measurements as uncertainty in k⊥ (∼5%) can propagate and grow for uncertainty in k∥. In this paper, we present a method for the simultaneous measurement of k⊥ and k∥ using beam-offset frequency domain thermoreflectance (FDTR) with robust uncertainty estimation. The conventional diffusive heat transfer solution is analyzed to show that offset and heating frequency can independently control the sensitivity to directional thermal conductivity and extract values for k∥ and k⊥. Numerical uncertainty analyses demonstrate that sweeping both heating frequency and beam offset results in a reduction of measurement uncertainty. This modified measurement technique is demonstrated on crystalline alumina (c-Al2O3), amorphous alumina (a-Al2O3), quartz, fused silica, and highly oriented pyrolytic graphite.

Giant Phonon Anharmonicity and Anomalous Pressure Dependence of Lattice Thermal Conductivity in Y2Si2O7 silicate.

Modification of lattice thermal conductivity (κL) of a solid by means of hydrostatic pressure (P) has been a crucially interesting approach that targets a broad range of advanced materials from thermoelectrics and thermal insulators to minerals in mantle. Although it is well documented knowledge that thermal conductivity of bulk materials normally increase upon hydrostatic pressure, such positive relationship is seriously challenged when it comes to ceramics with complex crystal structure and heterogeneous chemical bonds. In this paper, we predict an abnormally negative trend dκL/dP < 0 in Y2Si2O7 silicate using density functional theoretical calculations. The mechanism is disclosed as combined effects of slightly decreased group velocity and significantly augmented scattering of heat-carrying acoustic phonons in pressured lattice, which is originated from pressure-induced downward shift of low-lying optic and acoustic phonons. The structural origin of low-lying optic phonons as well as the induced phonon anharmonicity is also qualitatively elucidated with respect to intrinsic bonding heterogeneity of Y2Si2O7. The present results are expected to bring deeper insights for phonon engineering and modulation of thermal conductivity in complex solids with diverging structural flexibility, enormous bonding heterogeneity, and giant phonon anharmonicity.

Lattice thermal conductivity of NiTiSn half-Heusler thermoelectric materials from first-principles calculations

The microscopic physics behind the lattice thermal conductivity of NiTiSn is investigated using first-principles-based anharmonic lattice dynamics. The calculated lattice thermal conductivity of bulk materials (5.3 W m−1 K−1) is in good agreement with the experimental value at the optimal working temperature (700 K), but is overestimated below this temperature. The calculated values can be strongly affected by the size of the crystalline grains. We show that the lattice thermal conductivity is dominated by the acoustic (transverse and mostly longitudinal) modes with no contribution from the optical modes. The acoustic phonons are located below 150 cm−1 and involve mainly the tin atoms. The calculated mean free path of the most heat carrying phonons is around fifty nanometers with a maximum life time of ∼100 ps. These theoretical results are a step forward in developing the experimental design of low thermal conductivity NiTiSn Heusler based materials.

Simple model for effective thermal conductivity of bulk nanostructured materials

The ability to design and predict effective thermal transport properties in bulk nanostructured materials is becoming increasingly important as the demand for higher performance and higher efficiency electronics and energy conversion devices grows. A tremendous effort has been focused on understanding and improving our ability to predict thermal transport at an individual interface, resulting in new models that account for phonon populations and electron–phonon coupling. Despite the success of this work, there has been no effort to produce a simple analytic model to predict the effective thermal conductivity of bulk materials that include nanoscale features.This paper focuses on applying knowledge of thermal interface resistances to the development of a simple analytic model that can be used for the efficient prediction of effective thermal transport behavior to aid in the design of thermoelectric materials and microelectronic devices. To this end, molecular dynamics simulations are performed to generate an initial model based on the effective thermal conductivity of in-plane and cross-plane superlattices and embedded nanoparticle and nanowire arrays. The model is then validated and generalized by comparing to existing computational and experimental data. Results shows that the effective thermal conductivity calculated from the analytic model agrees well with that of various systems of different materials and geometries, and provides the ability to predict effective system thermal conductivity of these material systems with variable interface area for optimization of thermal transport properties.

Competing mechanism driving diverse pressure dependence of thermal conductivity ofXTe(X=Hg,Cd, and Zn)

Effectively engineering the lattice thermal conductivity of materials is a key interest of the current thermal science community. Pressure or compressive strain is one of the most worthwhile processes to modify the thermal transport property of materials, due to its robust tunability and flexibility of realization. While it is well documented in the literature that the application of hydrostatic pressure normally increases the thermal conductivity of bulk materials, little work has been performed on abnormal pressure-dependent thermal conductivity and the governing mechanism has not been fully understood yet. In this paper, taking bulk telluride systems $X\text{Te}$ $(X=\mathrm{Hg},\phantom{\rule{0.16em}{0ex}}\mathrm{Cd},\phantom{\rule{0.16em}{0ex}}\mathrm{Zn})$ as examples, we show, by combining first-principle calculation and the phonon Boltzmann transport equation, that the thermal conductivity presents diverse pressure dependence although they belong to the same group. The thermal conductivity of ZnTe is independent of pressure, while abnormal negative pressure dependence of thermal conductivity is observed in HgTe. As for CdTe, the trend falls in between HgTe and ZnTe and relies largely on the temperature. By comparing the key contributors of the lattice thermal conductivity, we find that the diverse pressure dependence of the lattice thermal conductivity is governed by the competition between the enhancement of group velocity of longitudinal acoustic and optic modes and the reduction of phonon relaxation time of transverse acoustic modes, with both effects being fully quantified by our calculation. Comparison with traditional bulk systems such as silicon further underpins the governing mechanism. The correlation between the diverse thermal transport phenomena and the nature of the atomic bonding is also qualitatively established. These findings are expected to deepen our understanding of manipulating phonon transport of bulk materials via simple compressive strain and are also helpful for related applications, such as optimizing thermoelectric performance.

Effect of carbon nanotube interfacial geometry on thermal transport in solid–liquid phase change materials

Abstract For nearly two decades, research groups have attempted to increase the thermal conductivity of bulk materials by saturating them with different concentrations and types of nanoparticles. However, optimal enhancements in the thermal conductivity of these materials continue to go unrealized, primarily due to interfacial phenomena that impede phonon propagation from the bulk material to the nanoparticle or between individual, contacting nanoparticles. Though it is almost certain that interfacial resistances between contacting nanoparticles are responsible for the underwhelming thermal performance of nanoparticles in bulk materials, the physical mechanisms that limit thermal transport at nanoparticle junctions is not well understood. In this study, we investigate the effect of nanoparticle constriction size (i.e. the contact area between linked nanoparticles) on the bulk thermal conductivity of a surrounding paraffin-based phase change material. To this end, we measure the effective thermal conductivity of different Multi-walled Carbon Nanotube (MWCNT)/paraffin nanocomposites is measured with the transient plane source technique. Using a newly developed physical model, the interfacial thermal resistance between the contacting nanoparticles is determined as a function of the constriction geometry. Results suggest that the thermal conductance (i.e. the rate of heat transfer) between contacting MWCNTs can be increased by a factor of 27 by increasing their diameter by only 58 nm. This is in direct conflict with effective medium approximations, which predict an increase in the bulk thermal conductivity of MWCNT–PCM composites when MWCNT diameters are reduced. Such a result indicates that the contact area between individual, contacting nanoparticles has a significant impact on thermal transport within the PCM nanocomposite, and therefore its bulk thermal conductivity. It is expected that these results will strongly impact the design of nanoparticle-laden PCMs.

Optimization of High Porosity Thermal Barrier Coatings Generated with a Porosity Former

Yttria-stabilized zirconia thermal barrier coatings are extensively used in turbine industry; however, increasing performance requirements have begun to make conventional air plasma sprayed coatings insufficient for future needs. Since the thermal conductivity of bulk material cannot be lowered easily; the design of highly porous coatings may be the most efficient way to achieve coatings with low thermal conductivity. Thus the approach of fabrication of coatings with a high porosity level based on plasma spraying of ceramic particles of dysprosia-stabilized zirconia mixed with polymer particles, has been tested. Both polymer and ceramic particles melt in plasma and after impact onto a substrate they form a coating. When the coating is subjected to heat treatment, polymer burns out and a complex structure of pores and cracks is formed. In order to obtain desired porosity level and microstructural features in coatings; a design of experiments, based on changes in spray distance, powder feeding rate, and plasma-forming atmosphere, was performed. Acquired coatings were evaluated for thermal conductivity and thermo-cyclic fatigue, and their morphology was assessed using scanning electron microscopy. It was shown that porosity level can be controlled by appropriate changes in spraying parameters.

Reduced temperature-dependent thermal conductivity of magnetite thin films by controlling film thickness

We report on the out-of-plane thermal conductivities of epitaxial Fe3O4 thin films with thicknesses of 100, 300, and 400 nm, prepared using pulsed laser deposition (PLD) on SiO2/Si substrates. The four-point probe three-omega (3-ω) method was used for thermal conductivity measurements of the Fe3O4 thin films in the temperature range of 20 to 300 K. By measuring the temperature-dependent thermal characteristics of the Fe3O4 thin films, we realized that their thermal conductivities significantly decreased with decreasing grain size and thickness of the films. The out-of-plane thermal conductivities of the Fe3O4 films were found to be in the range of 0.52 to 3.51 W/m · K at 300 K. For 100-nm film, we found that the thermal conductivity was as low as approximately 0.52 W/m · K, which was 1.7 to 11.5 order of magnitude lower than the thermal conductivity of bulk material at 300 K. Furthermore, we calculated the temperature dependence of the thermal conductivity of these Fe3O4 films using a simple theoretical Callaway model for comparison with the experimental data. We found that the Callaway model predictions agree reasonably with the experimental data. We then noticed that the thin film-based oxide materials could be efficient thermoelectric materials to achieve high performance in thermoelectric devices.

Role of phonon dispersion in studying phonon mean free paths in skutterudites

Experimental thermal conductivity of bulk materials are often modeled using Debye approximation together with functional forms of relaxation time with fitting parameters. While such models can fit the temperature dependence of thermal conductivity of bulk materials, the Debye approximation leads to large error in the actual phonon mean free path, and consequently, the predictions of the thermal conductivity of the nanostructured materials using the same relaxation time are not correct even after considering additional size effect on the mean free path. We investigate phonon mean free path distribution inside fully unfilled (Co4Sb12) and fully filled (LaFe4Sb12) bulk skutterudites by fitting their thermal conductivity to analytical models which employ different phonon dispersions. We show that theoretical thermal conductivity predictions of the nanostructured samples are in agreement with the experimental data obtained for samples of different grain sizes only when the full phonon dispersion is considered.

Thin-Film Thermal-Conductivity Measurement on Semi-Conducting Polymer Material Using the 3ω Technique

Organic solar cells have gained increasing interest in recent years due to their promising low-cost processing possibility and high throughput compared to inorganic solar cells. Since the efficiency of organic solar cells is still low, further optimization has to be done. Reliable simulation of solar cell layout and performance strongly depends on correct input data of the electrical and thermal transport properties of the applied film materials. In many cases these material properties are only available for bulk material if available at all. Owing to the given film thicknesses on the order of tenths to hundreds of nanometer and to the preparation methods, the properties of the used system can differ from the bulk material values. For determination of the thin-film thermal conductivity, only a few measurement methods are known to provide accurate results with one of them being the 3ω technique. It allows the determination of the thermal conductivity of bulk materials as well as thin films down to a thickness of around 50 nm. This study is part of an investigation on the influence of local hot spots, generated by defects in the active layer of organic solar cells, and on the charge carrier mobility as well as the propagation of the hot spot due to the thermal conduction of the material. Applying the 3ω technique, the effective thermal conductivity of solution-derived poly(3-hexylthiophene) thin films of different thickness on a common glass substrate was investigated.

Measurement of thermal impedance of GaN HEMTs using 3 method

This reported work deals with an accurate characterisation method dedicated to the determination of the thermal impedance of gallium nitride based high electron mobility transistors (GaN HEMTs). The method is inspired by the ‘3ω method’ initially proposed by Cahill (reference 8 of this Letter) in order to measure the thermal conductivity of bulk materials or layers and the present authors&apos; previous works on thermal resistance measurements. It is demonstrated that the voltage oscillation at the third harmonic is a real image of the thermal impedance of the device in the frequency domain. Both the theoretical approach and the test bench are discussed.

Strain effects on the thermal conductivity of nanostructures

Applying stress/strain on a material provides a mechanism to tune the thermal conductivity of materials dynamically or on demand. Experimental and simulation results have shown that thermal conductivity of bulk materials can change significantly under external pressure (compressive stress). However, stress/strain effects on the thermal conductivity of nanostructures have not been systematically studied. In this paper, equilibrium molecular-dynamics (EMD) simulation is performed to systematically study the strain effects on the lattice thermal conductivity of low-dimensional silicon and carbon materials: silicon nanowires (one dimensional) and thin-films (two dimensional), single-walled carbon nanotube (SWCNT, one dimensional) and single-layer graphene sheet (two dimensional). Spectral analysis of EMD is further developed and then applied to avoid the numerical artifacts such as the neglect of long-wavelength phonons that are often encountered when using EMD with periodic boundary conditions. Intrinsic thermal conductivity of the simulated bulk and nanostructures can be obtained using spectral analysis of EMD. The thermal conductivity of the strained silicon and diamond nanowires and thin films is shown to decrease continuously when the strain changes from compressive to tensile. However, for SWCNT and single-layer graphene, the thermal conductivity has a peak value, and the corresponding applied strain is at $\ensuremath{-}0.06$ or $\ensuremath{-}0.03$ for SWCNTs depending on the chirality and at zero for graphene, respectively. The following two reasons could explain well the effects of strains on the thermal conductivity of the nanowires and thin films that decreases continuously from compressive strain to tensile strain: (1) mode-specific group velocities of phonons decrease continuously from compressive strain to tensile strain and (2) the specific heat of each propagating phonon modes decrease continuously from compressive strain to tensile strain. However, for SWCNT and single-layer graphene, the mechanical instability induces buckling phenomenon when they are under compressive strains. The phonon-phonon scattering rate increases significantly when the structure buckles. This results in the decreasing behavior of thermal conductivity of SWCNT and graphene under compressive stress and explains the peak thermal conductivity value observed in SWCNT and single-layer graphene when they are under strain. The results obtained in this paper has important implications of challenging thermal management of electronics using advanced materials such as carbon nanotubes and graphene. It also points to a potentially new direction of dynamic thermal management.

Single track formation in selective laser melting of metal powders

Selective laser melting (SLM) is a powder-based additive manufacturing capable to produce parts layer-by-layer from a 3D CAD model. Currently there is a growing interest in industry for applying this technology for generating objects with high geometrical complexity. To introduce SLM process into industry for manufacturing real components, high mechanical properties of final product must be achieved. Properties of manufactured parts depend strongly on each single laser-melted track and each single layer. In this study, effects of the processing parameters such as scanning speed and laser power on single tracks formation are explored. Experiments are carried out at laser power densities (0.3–1.3) × 10 6 W/cm 2 by cw Yb-fiber laser. Optimal ratio between laser power and scanning speed (technological processing map) for 50 μm layer thickness is determined for stainless steels (SS) grade 316L (−25 μm) and 904L (−16 μm), tool steel H13 (−25 μm), copper alloy CuNi10 (−25 μm) and superalloy Inconel 625 (−16 μm) powders. A considerable negative correlation is found between the thermal conductivity of bulk material and the range of optimal scanning speed for the continuous single track sintering.