High Temperature Domain Research Articles

High-temperature phase transitions and domain structures of KLiSO4: studied by polarisation-optics, X-ray topography and liquid–crystal surface decoration

Abstract The transitions between the room temperature phase III (space group P63) and the two high-temperature phases II (Pcmn) and I (P63/mmc) of KLiSO4 and the domain structures generated by them were investigated by high-temperature polarisation optics (birefringence) and room-temperature X-ray topography, optical activity and nematic–liquid–crystal (NLC) surface decoration. The transition from the polar hexagonal phase III into the centrosymmetric orthorhombic phase II at 708 K leads, due to the loss of the trigonal axis and the radial temperature gradient of the optical heating chamber used, to a roughly hexagonal arrangement of three sets of thin orthorhombic {110} lamelleae with angles of 60° (120°) between them. The associated twin law “reflection m{110}orth” corresponds to the frequent growth twin m{101̅0}hex of phase III. The domains are easily ferroelastically switched. Upon further heating above 949 K into phase I (P63/mmc) all domains vanish. Upon cooling back into phase II the three domain states related by 60°(120°) reflections m{110}orth re-appear, however (due to the higher thermal agitation at 949 K) with a completely different domain structure consisting of many small, irregularly arranged {110}orth domains. Particular attention is paid to the domain structure of the hexagonal room temperature phase III generated during the re-transition from the orthorhombic phase II. Curiously, from the expected three twin laws inversion 1̅, rotation 2⊥[001]hex and reflection m{101̅0}hex only the latter, which corresponds to the frequent growth twinning, has been found. Finally a short treatise of the structural relations of the KLiSO4 high-temperature polymorphs is given.

Protocol and Validation of CHARMM-GUI Hex Phase Builder

It is becoming increasingly apparent that protein dynamics, conformation, and therefore, function are dependent on the stresses within the bilayer – one of which being bending frustration. The amount of bending frustration is dependent on the bending modulus (kc) and spontaneous radius of curvature (R0–1) for a given lipid composition. These quantities are difficult to obtain computationally, particularly by all-atom molecular dynamics (MD) simulation. For many years, experimentalists (and much more recently, simulators) have used the lipid hexagonal phase to obtain these quantities. The inverse lipid hexagonal phase exists in high temperature and low water domains of the certain lipid's phase diagram. In this phase, lipids aggregate with their hydrophilic heads oriented along hexagonally packed water pores. Although this phase spontaneously assembles, the equilibration time necessary for this type of process is unfeasible for typical all-atom MD simulations. Here, a simple and reproducible methodology, Hex Phase Builder, is described and validated as an integrated part of the CHARMM-GUI framework (http://www.charmm-gui.org/input/hexphase). By calculating the pressure within the water pore, kc and R0–1 can be obtained for any lipid composition. This sensitive technique provides energetic insight into lipid systems and allows for further validation of the oft-used CHARMM C36 lipid force field.

Chiral symmetry transition in the linear sigma model with quarks: Counting effective QCD degrees of freedom from low to high temperature

We use the linear sigma model coupled to quarks, together with a plausible location of the critical end point (CEP), to study the chiral symmetry transition in the QCD phase diagram. We compute the effective potential at finite temperature and density up to the contribution of the ring diagrams, both in the low and high temperature limits, and use it to compute the pressure and the position of the CEP. In the high temperature regime, by comparing to results from extrapolated lattice data, we determine the model coupling constants. Demanding that the CEP remains in the same location when described in the high temperature limit, we determine again the couplings and the pressure for the low temperature regime. We show that this procedure gives an average description of the lattice QCD results for the pressure and that the change from the low to the high temperature domains in this quantity can be attributed to the change in the coupling constants which in turn we link to the change in the effective degrees of freedom.

Radial two-phase thermal conductivity of ceramic sponges up to high temperatures – experimental results and correlation

The experimental determination of the radial two-phase thermal conductivity with forced convection (often also called effective thermal conductivity) at high temperatures up to 1100 K for different ceramic sponges (variation of material, porosity and cell size) is presented. The experimental results are shown and dependencies are clarified. The sponges investigated were made of alumina, mullite, oxidic-bonded silicon carbide (OBSiC) and silicon infiltrated silicon carbide (SiSiC). They have porosities between 75% and 88% and cell densities in the range of 10 ppi to 30 ppi. Due to the high temperature domain, the thermal radiation is significant and cannot be neglected. The radial two-phase thermal conductivity under forced convection conditions is highly dependent on the superficial air velocity, the temperature, the porosity and the cell size of the sponge sample. Furthermore, for future prediction of the radial two-phase thermal conductivity of sponges, a correlation based on an approach summing up the different underlying heat transfer mechanisms is developed.

An HPLC method associated with a thermodynamic analysis to compare the binding of TRAIL and its nanovectorized form to death receptors DR4 and DR5 and their relationship to cytotoxicity.

TRAIL is a member of the TNF family of cytokines which induces apoptosis of cancer cells via its binding to its cognate receptors, DR5 a high affinity site and DR4 a site of low affinity. Our working group has recently demonstrated that nanovectorization of TRAIL with single wall carbon nanotubes (abbreviated NPT) enhanced TRAIL affinity to the high affinity site DR5 and increased pro apoptotic potential in different human tumor cell lines. In this paper, the DR4 low affinity site was immobilized on a chromatographic support and the effect of temperature on a wide temperature range 1°C-50°C was studied to calculate the thermodynamic parameters of the binding of TRAIL and NPT to DR4 and DR5 receptors. For the first time the heat capacity changes for the different binding processes were determined. At a physiological pH (7.4) the heat capacity changes for the binding of NPT to DR4 and DR5 were respectively equal to -0.91kJ/molK and -0.28kJ/molK and those obtained for the binding of TRAIL to DR4 and DR5 were respectively equal to -1.54kJ/molK and -1.05kJ/molK. By the use of differential scanning calorimetry (DSC), a phase transition (∼12°C for DR5, ∼4°C for DR4) between a disordered (low temperature) and an ordered (high temperature) solid like state visualized in the receptor structure confirmed the temperature dependence of binding affinity enthalpy ΔH for soluble TRAIL and its nanovectorized form to its cognate receptors. In the low temperature domain, the positive ΔH values contribute non-favourably to the free energy of binding, TRAIL and NPT described similar affinities for DR4 and DR5. For the high temperature domain, negative ΔH values indicated that van der Waals interactions and hydrogen bonding are engaged favourably at the ligand - receptor interface. Above 30°C, their rank-ordered affinities were thus strongly different in the sequence: TRAILDR4<NPTDR4<TRAILDR5< NPTDR5. The nanovectorization of TRAIL enhanced its binding to both DR4 and DR5 receptors at 37°C and could potentially sensitized cancer cells to TRAIL induced apoptosis through simultaneous activation of DR4 and DR5 as described in this paper for the non-small lung carcinoma cell line (H1703), the two hepatocarcinoma cell lines (SK-Hep1, HUH) and the colon carcinoma cell line (HCT116WT). The excellent linear coefficient (r2=1) for the plot comparing NPT cytotoxicity to TRAIL cytotoxicity confirmed a high degree of similarity for the mechanism of cytotoxicity of TRAIL and NPT between these four cell lines expressing DR4 and DR5 receptors. The slope (0.10) and the negative intercept (-1.23) of this plot indicated that NPT was much more efficient in these four cell lines as compared to TRAIL alone. As well, it was shown that the extra cellular acidosis led to the protonation of the TRAIL residue histidine by flipping the His switch to the on position with a concomitant decrease in affinity for DR4 and DR5 receptors. The highest affinity for NPT to DR4 and DR5 receptors observed at low pHs was due to the less accessibility of the His molecular switch to be protonated when TRAIL was immobilized on CNTs.

Characterization of hot deformation behavior of alloy 617 through kinetic analysis, dynamic material modeling and microstructural studies

The hot deformation behavior of alloy 617 has been studied by performing hot compression in a range of temperatures (1173–1473K) and strain rates (0.001–10s−1). The peak flow stress found to increase with Zener–Hollomon parameter (Z) following a hyperbolic-sine function relationship whereas peak strain followed power-law type relationship with Z. The average activation energy for the entire hot deformation domain was estimated to be 481kJmol−1. The experimental stress-strain data has been used to develop processing map employing dynamic material model. The material exhibits a wide stable domain below 0.1s−1 spanning over 1250–1473K, with a peak efficiency of ~45%. Based on the processing map and subsequent microstructural observation, the optimum hot deformation domain of alloy 617 is identified as 1323–1423K and 0.001–0.1s−1. Furthermore, microstructural observation alone has revealed that a significant DRX with grain refinement could also be obtained at high temperature (>1373K) and high strain rate (>1s−1) domain although processing map has marked this region as unstable domain.

Origin and geochemistry of agates in Permian volcanic rocks of the Sub-Erzgebirge basin, Saxony (Germany)

Mineralogical and geochemical investigations of agates from Permian volcanic rocks of the Sub-Erzgebirge basin (Saxony, Germany) were made to constrain the genesis and characteristics of these spectacular forms of silica in acidic volcanic host rocks. Samples from the main agate occurrences of Chemnitz, Hohenstein-Ernstthal, St. Egidien and Zwickau were selected for detailed analyses.The results of the study show that agate formation can be related to volcanic activity (Rochlitz ignimbrite) and the subsequent alteration of the volcanic rocks. Most agates originate from the infill of silica into cavities of lithophysae (high-temperature crystallization domains), which formed during cooling of welded ignimbrite. Agate formation temperatures of probably >150°C were calculated from fluid inclusion and oxygen isotope studies, which indicate that the mobilization and accumulation of silica started already during a late phase of or soon after the volcanic activity.The trace-element composition of chalcedony and macrocrystalline quartz in agates is different from that of quartz from magmatic or metamorphic rocks and pegmatites. Elements of the volcanic rock matrix (Al, Ca, Fe, Na, K) were released during the alteration processes and accumulated in the SiO2 matrix of the agates. Extraordinary high contents of Ge (>90ppm), B (46ppm) and U (>18ppm) were also detected, which can exceed the Clark concentration and sometimes the element concentration in the surrounding host rocks. In addition, chondrite-normalized REE distribution patterns of the agates show strong negative Eu-anomalies, enriched HREE as well as tetrad effects. These patterns are different from the REE patterns of the volcanic host rocks and point to fractionation processes during agate formation. The specific geochemical features indicate interactions of the host rocks with magmatic volatile fluids and heated meteoric water, and transport of SiO2 and other elements both in aqueous solution and via stable fluorine (and chlorine) compounds such as SiF4, BF3, GeF4, and UO2F2.The results of cathodoluminescence (CL) microscopy and spectroscopy revealed a microstructure of the agates that is similar for all occurrences. Characteristic features are irregular internal textures and sector zoning in quartz as well as luminescence colours and spectra, respectively, which are caused by a typical high defect density (oxygen vacancies, silanol groups). According to these results, the formation of agates can be explained by crystallization via an amorphous silica precursor under non-equilibrium conditions.

Comparison of Alternative Molten Electrolytes for Water Splitting to Generate Hydrogen Fuel

This study explores a new high temperature molten hydroxide domain to electrochemically split water into hydrogen fuel. Hydrogen fuel, if produced without greenhouse gas emissions, is a promising fuel for transportation. This study opens a pathway to low energy water splitting and the electrolytic production of hydrogen fuel without carbon dioxide emission. A wide range of pure and mixed alkali and alkali earth hydroxide electrolytes are explored at temperatures ranging from 200 to 700°C. Higher temperature leads to improved (lower voltage) water splitting and improved rates of charge transfer, but carries challenges (increased rates of parasitic side reactions as the molten electrolytes dehydrate with increasing temperature). This study extends the range of hydrogen formation in alkaline electrolysis water splitting to over 600°C, and demonstrates that lithium and/or barium hydroxide electrolytes remain hydrated at high temperatures, and in the high temperature domain are advantageous over sodium or potassium hydroxide electrolytes. In pure LiOH, the coulombic efficiency for hydrogen generation decreases with temperature and is measured respectively at ηH2 = 88%, 21%, 4% and 0%, respectively at 500, 600, 700 and 800°C.

Electronic transport and magnetoresistivity of La0.4Bi0.1Ca0.5−x Sr x MnO3 (x = 0.1 and 0.2)

Electrical resistivity and magnetoresistive behaviour of bismuth-substituted lanthanum manganites La0.4Bi0.1Ca0.5−x Sr x MnO3 (x = 0.1 and 0.2) were systematically studied by varying the temperature from 2 to 300 K and the magnetic field up to 12 T. The samples were found to crystallize in rhombohedral structure and their morphology shows near-spherical nanosize crystallites. Charge ordering was observed in both the samples under zero field conditions and corresponding transition temperature T CO was found to decrease with the increase of x. Resistivity measurements with magnetic field also showed suppression of magnetoresistivity (MR) with the increase of x and the maximum MR was found to be 98 and 93% for x = 0.1 and 0.2, respectively, at 10 T. In the high-temperature domain, the electronic transport was observed to be dominated by the variable range hopping mechanism for both the samples, whereas in the low-temperature domain the electrical conduction of x = 0.1 sample was observed to be contributed by various other electron scattering mechanisms.

In-situ high-temperature domain structures of die-upset Nd–Fe–B magnets

Magnetic domains of a die-upset Nd–Fe–B magnet with an energy product of about 50MGOe are investigated by using in-situ magnetic force microscopy (MFM), varying temperature from room temperature to 240°C. For both as-prepared and magnetized Nd–Fe–B samples, the domain-pattern evolution during thermal demagnetization is monitored by MFM. The temperature dependence of the evolution of reverse domains is explained by micromagnetic models. At all temperatures, the magnetization reversal in the technological relevant magnetized limit proceeds by nucleation.

Oxidation Assisted Intergranular Cracking in Alloy 718: Effects of Strain Rate and Temperature

Alloy 718 is the most widely used superalloy in industry due to its excellent mechanical properties, as well as its oxidation and corrosion resistance over a wide range of temperatures and solicitation modes. Nevertheless, it is a well-known fact that this alloy is sensitive to oxidation assisted intergranular cracking under loading in the temperature range encountered in service. The mechanisms resulting in such degradation are not well-understood, but it has been well established that a relation exists between a change in fracture mode and the apparition of plastic instability phenomena over a wide range of temperatures. Quantification and characterization of the damaging process provide important information leading to a better understanding of the degradation mechanisms involved in the oxidation assisted intergranular cracking of this alloy. These observations allow various domains to be defined in the strain rate - temperature plane, where the damaging process characteristics are different: a high strain rate / low temperature domain in which instabilities occur and where the fracture mode is systematically transgranular ductile, an intermediary domain where numerous intergranular crack initiations can be observed, and a slow strain rate / high temperature domain where crack propagation is enhanced. These results lead to the proposal of consistent scenarii to explain grain boundary opening due to applied intergranular normal stress and critical decohesion stress changes.

Terrestrial Carbonaceous Debris Tracing Atmospheric Hypervelocity-Shock Aeroplasma Processes

Atmospheric hypervelocity impacts are widely viewed to produce the meteoric smoke layer by the shock-less interactions of the impinging air molecules with the vaporized meteoroid. In contrast here, we intend to show how gas and solid aerosols when captured in the Mach cone of a bolide while entering the Earth atmosphere are transformed into a new range of polymeric nanomaterials. Carbonaceous materials from natural situations are studied from collect in a pilot region of Southern France in the following days of a high altitude meteor atmospheric airburst on 2011 August 2nd and since the 2013 February 15th Chelyabinsk meteoritic event in Ural. These materials are compared to the ones obtained by hypervelocity shock with the CEA Persephone light-gas gun. A numerical simulation with the Tycho software is performed to model the evolution of the increase of density directly in the rear front of the shockwave with the increase of velocity around an obstacle for high velocity inflow. The multidisciplinary approach reveals the production carbon-based nanosolids from terrestrial precursors by hypervelocity plasma particle deposition (HPPD) processes. The Tycho simulation helps to establish the lack of mixing between the ablation smoke and the surrounding atmosphere. The correlation between the simulation, the hypervelocity experiments and the natural situations shows the distinctive characteristics of visco-elastic filamentary nanosolids formed in the laminar domain of low pressure, the ones of nanoparticle-rich stiff film specific to the thin domain of high shear stress and the ones of dense glassy carbon with nanocarbon crystallites (graphite and graphene-like) only formed in the frontal high temperature and pressure domain. Data on the natural carbon-based nanosolids indicate that the atmospheric shock-dissociation occurred from a carbon pool dominated by dead atmospheric carbon. Diagnostic keys are provided to distinguish natural carbon-based nanosolids synthesized by HPPD just at the time of the hypervelocity atmospheric entry from their subsequent transformations during atmospheric transport by other aeroplasma processes.

Microstructural evolution of a 304-type austenitic stainless steel during rolling at temperatures of 773–1273 K

The structural changes leading to grain refinement in a 304-type austenitic stainless steel subjected to warm caliber rolling over a wide temperature range of 773–1273K were studied. The development of a new ultrafine-grained structure during rolling primarily resulted from continuous dynamic recrystallization. Two deformation domains were recognized that exhibit different recrystallization processes. In the high-temperature deformation domain, the majority of new strain-induced grain boundaries developed homogeneously through largely uniform formation of a network of deformation sub-boundaries, the misorientations of which attained values of high-angle grain boundaries during deformation. In this case, the kinetics of the microstructural evolution depended on dynamic recovery, which accelerated with increasing deformation temperature. In contrast, the development of new strain-induced grain boundaries was primarily associated with deformation microbanding in the low-temperature deformation domain. The development of deformation microbands resulted from strain localization and was promoted by a decrease in the deformation temperature. Therefore, the opposite temperature effect on the contribution of different structural mechanisms to new grain development led to temperature-independent kinetics of grain refinement for a wide range of warm working.

Superelastic property induced by low-temperature heating of a shape memory Ti–24Nb–0.5Si biomedical alloy

In this study, we have explored a new way to obtain a superelastic titanium-based alloy. Contrary to the classical method, which consists of obtaining the β microstructure directly by water quenching from the high-temperature β-phase domain, this way consists of obtaining first a shape memory alloy displaying a fully α″ martensitic microstructure and then producing superelastic behavior by applying low-temperature heating.

Single-molecule magnetism in a family of {Co(III)2Dy(III)2} butterfly complexes: effects of ligand replacement on the dynamics of magnetic relaxation.

The synthesis and structural characterization of four related heterometallic complexes of formulas [Dy(III)2Co(III)2(OMe)2(teaH)2(O2CPh)4(MeOH)4](NO3)2·MeOH·H2O (1a) and [Dy(III)2Co(III)2(OMe)2(teaH)2(O2CPh)4(MeOH)2(NO3)2]·MeOH·H2O (1b), [Dy(III)2Co(III)2(OMe)2(dea)2(O2CPh)4(MeOH)4](NO3)2 (2), [Dy(III)2Co(III)2(OMe)2(mdea)2(O2CPh)4(NO3)2] (3), and [Dy(III)2Co(III)2(OMe)2(bdea)2(O2CPh)4(MeOH)4](NO3)2·0.5MeOH·H2O (4a) and [Dy(III)2Co(III)2(OMe)2(bdea)2(O2CPh)4(MeOH)2(NO3)2]·MeOH·1.5H2O (4b) are reported (teaH3 = triethanolamine, deaH2 = diethanolamine, mdeaH2 = N-methyldiethanolamine, and bdeaH2 = N-n-butyldiethanolamine). Compounds 1 (≡ 1a and 1b) and 4 (≡ 4a and 4b) both display two unique molecules within the same crystal and all compounds display a butterfly type core, with the Dy(III) ions occupying the central body positions and the diamagnetic Co(III) ions the outer wing-tip sites. Compounds 1-4 were investigated via direct current and alternating current magnetic susceptibility measurements, and it was found that each complex displayed single-molecule magnet (SMM) behavior. All four compounds display unique coordination and geometric environments around the Dy(III) ions and it was found that each displays a different anisotropy barrier. Ab initio calculations were performed on 1-4 and these determined the low lying electronic structure of each Dy(III) ion and the magnetic interactions for each cluster. It was found that there was a strong correlation between the calculated energy gap between the ground and first excited states of the single-ion ligand-field split Dy(III) levels and the experimentally observed anisotropy barrier. Furthermore, the transverse g factors found for the Dy(III) ions, defining the tunnelling rates within the ground Kramers doublets, are largest for 1, which agrees with the experimental observation of the shortest relaxation time in the high-temperature domain for this complex. The magnetic exchange between the Dy(III) ions revealed overall antiferromagnetic interactions for each compound, derived from the dominant dipolar exchange resulting in nonmagnetic ground states for 1-4. The diamagnetic ground states coupled with small tunneling gaps resulted in quantum tunneling time scales at zero field of between 0.1 and >1.5 s.

Hot deformation behavior and processing map of a γ′-hardened nickel-based superalloy

The hot deformation behavior of a γ′-hardened nickel-based superalloy was investigated by means of isothermal compression tests in the temperature range of 1010–1160°C and strain rate range of 0.001–1s−1. The results show that the hot activation energy of the alloy is about 427.626kJ/mol. On the basis of experimental data, processing maps were developed by utilizing the principles of the dynamic materials model (DMM). The processing maps exhibit one domain with high efficiency of power dissipation. At the strain of 0.6, the domain occurs in the temperature range of 1105–1160°C and strain rate range of 0.02–0.25s−1 with a peak efficiency of about 42.2%. Microstructure observations reveal that full dynamic recrystallization (DRX) occurred in the domain. In the processing maps, the curvature changes of the isoefficiency contours occur in the temperature range of 1080–1090°C, which is at the dissolution temperature of γ′ phase in the alloy. Moreover, it can be found that the strain has an effect on the efficiency of power dissipation. The efficiency value increases with increasing strain in the high strain rate domain (0.1–1s−1), while the efficiency value decreases with increasing strain in the high temperature (1080–1160°C) and low strain rate (0.001–0.01s−1) domain. The flow instability is predicted to occur in the high strain rate domain, which is manifested as adiabatic shear bands.

Investigation into the hot workability of the as-extruded WE43 magnesium alloy using processing map

The research concerned the characterization of the hot-working behavior of the as-extruded WE43 magnesium alloy potentially for biomedical applications and the construction of processing maps to guide the choice of forming process parameters. Isothermal uniaxial compression tests were performed over a temperature range of 350–480°C and strain rate range of 0.001–10s−1. Flow stresses obtained were used to construct processing maps. Domains in processing maps corresponding to relevant deformation mechanisms, i.e., dynamic recrystallization (DRX), dynamic recovery (DRV) and flow instability, were identified, according to power dissipation efficiency and flow instability parameter values. Microstructures of compression-tested specimens were examined to validate these deformation mechanisms. Two mechanisms of DRX nucleation, i.e., particle-stimulated nucleation (PSN) and grain boundary bulging, were found to be operative at the low-temperature and high-temperature DRX domains, respectively. Flow instability was related to adiabatic shear bands and abnormal grain growth. An optimum condition for the hot working of this alloy was determined to be at a temperature of 475°C and a strain rate of 0.1s−1.

New insights into the relationship between dynamic softening phenomena and efficiency of hot working domains of a nitrogen enhanced 316L(N) stainless steel

In the present study, the dynamic recrystallization (DRX) behavior of a nitrogen enhanced 316L(N) stainless steel (with 0.14wt% N) has been studied in the temperature range of 1073–1423K and strain rate range of 0.001–10s−1 to understand the correlations between dynamic softening phenomena and efficiencies of hot working domains in the processing map. DRX fractions and the grain sizes in each condition were evaluated to develop DRX map and to study the grain growth. It was observed that the efficiency peaks of the stable domains are associated with increase in DRX fraction in the low temperature domain, increase in both DRX fraction and grain size at the medium temperature domain, and increase in grain size after saturation of DRX in the high temperature domain. Microstructures corresponding to high temperature unstable domain did not reveal any sign of conventional instabilities, instead show substantial amount of DRX grains. However, with increase in thermal energy neither a measurable increase in DRX fraction nor grain growth was observed. This mismatch between the energy input (through increase in temperature) and energy dissipation (through metallurgical phenomena) fulfills the instability criterion of dynamic materials model in this domain.

Domain growth and aggregation dynamics in photo-induced phase transition phenomena

We have studied domain growth dynamics in photo-induced phase transition phenomena on RbMn[Fe(CN)6] by measuring the time developments of the Raman peaks of the CN stretching modes, which are sensitive to the boundaries between high temperature and low temperature domains. Under the high excitation intensity, we observe abrupt increase and slow decrease of the boundary. This indicates creation of the small domains and subsequent growth process with domain aggregation. Experimental results are explained qualitatively by the mean field theory with the pair valence states of Fe and Mn pairs taking into account of instability of domain boundary.

Molecular- and domain-level microstructure-dependent material model for nano-segregated polyurea

Purpose – Polyurea is an elastomeric two-phase co-polymer consisting of nanometer-sized discrete hard (i.e. high glass transition temperature) domains distributed randomly within a soft (i.e. low glass transition temperature) matrix. A number of experimental investigations reported in the open literature clearly demonstrated that the use of polyurea external coatings and/or internal linings can significantly increase blast survivability and ballistic penetration resistance of target structures, such as vehicles, buildings and field/laboratory test-plates. When designing blast/ballistic-threat survivable polyurea-coated structures, advanced computational methods and tools are being increasingly utilized. A critical aspect of this computational approach is the availability of physically based, high-fidelity polyurea material models. The paper aims to discuss these issues. Design/methodology/approach – In the present work, an attempt is made to develop a material model for polyurea which will include the eff...