Glass Transition Activation Energy Research Articles

Experimental Investigation on the Mechanical and Dynamic Thermomechanical Properties of Polyether Ether Ketone Based on Fused Deposition Modeling

In this work, the mechanical and dynamic thermomechanical properties of PEEK based on FDM are experimentally investigated and evaluated comprehensively. The tensile failure mechanism of PEEK prepared by FDM and extrusion modeling (EM) was analyzed by fracture morphology observation. By conducting a differential scanning calorimetry (DSC) test, the crystallinity of PEEK prepared by FDM and EM was measured. The dynamic thermomechanical properties of PEEK were tested and analyzed by dynamic mechanical analysis (DMA). For FDM-prepared PEEK samples, the yield strength and elongation were 98.3 ± 0.49 MPa and 22.86 ± 2.12%, respectively. Compared with the yield strength of PEEK prepared by EM, the yield strength of PEEK prepared by FDM increased by 65.38%. The crystallinity of FDM-prepared and EM-prepared samples was calculated as 34.81% and 31.55%, respectively. Different processing methods resulted in differences in the microscopic morphology and crystallinity of two types of PEEK parts, leading to differences in mechanical properties. The internal micropores generated during the FDM processing of PEEK significantly reduced the elongation. Moreover, according to the DMA results, the glass transition activation energy of PEEK was obtained as ΔE = 685.07 kJ/mol based on the Arrhenius equation. Due to the excellent mechanical properties of PEEK prepared by FDM processing, it is promising for high-performance polymer applications in different fields.

Enthalpy relaxation of sodium aluminosilicate glasses from thermal analysis

AbstractThe sodium aluminosilicate (NAS) glass family is important for many different industrial applications, but glass relaxation has not yet been thoroughly studied in this system. Thermal analysis techniques such as differential scanning calorimetry (DSC) and modulated differential scanning calorimetry (MDSC) can provide insight into the enthalpy relaxation of glass by measuring the glass transition temperature (Tg), activation energy, and enthalpy of relaxation. MDSC is mostly used to study nonoxide and low Tg glasses, and there is much debate about whether the nonreversing heat flow analysis method is accurate. To the authors’ knowledge, this is the first paper using MDSC to study these NAS compositions, and one of few papers to report MDSC on high Tg oxide glasses. We report on one set of modulation conditions that obtain a linear response using Lissajous curves, as well as comparing the activation energy calculated from DSC with the enthalpy of relaxation obtained from MDSC. Our results show that the activation energy and enthalpy of relaxation do not give the same compositional minimum in relaxation, and therefore more work is needed to investigate the validity of the nonreversing heat flow approach for high Tg oxide glasses.

Composition design and crystallization behavior of Zr–Cu–Ni–Al bulk metallic glasses

The Zr–Cu–Ni–Al system was explored in this study, and seven new compositions of Zr-based bulk metallic glasses (BMGs) were designed by combining different proportions of binary eutectic phases Zr38Cu62, Zr76Ni24 and Zr51Al49, and rod-like shape samples were prepared with different diameters using the copper mold casting method. Modifying the proportion coefficient of these eutectic units, the width of the supercooled liquid region was increased from 79 to 95 K, and the thermal stability of the prepared metallic glass was improved. Differential scanning calorimetry was used to investigate the non-isothermal and isothermal crystallization behavior of the prepared samples. Noticeably, there was a small low-temperature exothermic peak before the glass transition temperature Tg in the non-isothermal crystallization process, which was related to the structural relaxation. The crystallization transition activation energy fitted by the Kissinger equation had the same variation trend as that obtained by the Arrhenius equation. Among the four metallic glasses studied, the glassy phase of Zr55·5Cu23·25Ni9Al12.25 was more stable, showing higher glass transition activation energy and longer incubation time. In addition, the isothermal crystallization processes of four metallic glasses were studied according to the Johnson-Mehl-Avrami (JMA) model. The calculated average Avrami exponents were >2.5, indicating that the nucleation rate increased during the isothermal crystallization process.

Glass Stability and Glass Forming Ability of Ge25−xSe75Sbx (x = 12, 15, and 18) Chalcogenide Glasses Using Thermal Parameters

AbstractIn the present communication glass stability (GS) and glass forming ability (GFA) of Ge25−xSe75Sbx (x = 12, 15, and 18) chalcogenide glasses have been calculated in terms of certain thermal parameters, i.e., reduced glass transition temperature (Trg), Hruby number (H), S‐parameter (S), and ΔT. The glassy samples have been prepared by quenching of melt technique. For structure characterization, XRD technique has been used. For thermal analysis Differential Scanning Calorimetery (DSC) has been used. DSC scans have been recorded at different heating rates, i.e., 5, 10, 15, and 20 K min−1. Stability of glassy samples has also been confirmed in terms of activation energy of glass transition calculated by Kissinger relation. All these parameters indicate that GS and GFA both decrease with increase of Sb content in Ge25−xSe75Sbx (x = 12, 15, and 18) glassy series.

A Comprehensive Review on the Thermal Stability Assessment of Polymers and Composites for Aeronautics and Space Applications.

This review article provides an exhaustive survey on experimental investigations regarding the thermal stability assessment of polymers and polymer-based composites intended for applications in the aeronautical and space fields. This review aims to: (1) come up with a systematic and critical overview of the state-of-the-art knowledge and research on the thermal stability of various polymers and composites, such as polyimides, epoxy composites, and carbon-filled composites; (2) identify the key factors, mechanisms, methods, and challenges that affect the thermal stability of polymers and composites, such as the temperature, radiation, oxygen, and degradation; (3) highlight the current and potential applications, benefits, limitations, and opportunities of polymers and composites with high thermal stability, such as thermal control, structural reinforcement, protection, and energy conversion; (4) give a glimpse of future research directions by providing indications for improving the thermal stability of polymers and composites, such as novel materials, hybrid composites, smart materials, and advanced processing methods. In this context, thermal analysis plays a crucial role in the development of polyimide-based materials for the radiation shielding of space solar cells or spacecraft components. The main strategies that have been explored to improve the processability, optical transparency, and radiation resistance of polyimide-based materials without compromising their thermal stability are highlighted. The combination of different types of polyimides, such as linear and hyperbranched, as well as the incorporation of bulky pendant groups, are reported as routes for improving the mechanical behavior and optical transparency while retaining the thermal stability and radiation shielding properties. Furthermore, the thermal stability of polymer/carbon nanocomposites is discussed with particular reference to the role of the filler in radiation monitoring systems and electromagnetic interference shielding in the space environment. Finally, the thermal stability of epoxy-based composites and how it is influenced by the type and content of epoxy resin, curing agent, degree of cross-linking, and the addition of fillers or modifiers are critically reviewed. Some studies have reported that incorporating mesoporous silica micro-filler or microencapsulated phase change materials (MPCM) into epoxy resin can enhance its thermal stability and mechanical properties. The mesoporous silica composite exhibited the highest glass transition temperature and activation energy for thermal degradation among all the epoxy-silica nano/micro-composites. Indeed, an average activation energy value of 148.86 kJ/mol was recorded for the thermal degradation of unfilled epoxy resin. The maximum activation energy range was instead recorded for composites loaded with mesoporous microsilica. The EMC-5p50 sample showed the highest mean value of 217.6 kJ/mol. This remarkable enhancement was ascribed to the polymer invading the silica pores and forging formidable interfacial bonds.

Mixed modifier effect in Na2O·K2O·CaO aluminosilicate glasses: Pairwise and ternary interactions

AbstractThe mixed modifier effect (MME) is one of the most challenging puzzles in the field of oxide glasses, as there exists no universal quantitative theoretical model for accurately describing and predicting the nonlinear deviation of property values. In this paper, pairwise and ternary interactions are examined experimentally to understand the MME in a series of aluminosilicate glasses. By keeping the glass network former concentration constant and adjusting the molar ratios of three network modifiers (Na2O, K2O, and CaO), the MMEs in glass transition temperature (Tg), Vickers hardness (Hv), and activation energy (Ea) for aqueous dissolution for each modifier cation are investigated. We examine whether a pairwise interaction model is sufficient, or if ternary interactions also need to be included to predict the MME in these aluminosilicate glass systems. This work reveals that the pairwise model can be used to predict the MME for Tg in complex multiple‐modifier glass systems using only two‐body interaction factors. However, ternary mixed‐modifier interactions are present in other properties such as Hv and Ea.

Phase transformation, thermal behavior, and magnetic study of new (FeSiBP)100-XCuX glassy alloys obtained by melt-spinning in air

In the current work, a new variation of the FeSiBPCu system with good glass forming ability and soft magnetic properties was developed and investigated. The effect of copper addition on the FeSiBP base alloy was studied in the system (Fe0.77Si0.08B0.1P0.05)100-xCux with x = 0, 0.25, 0.5, 0.75 and 1.0 at%. Microstructural evolution upon the annealing process was evaluated by XRD and TEM, revealing the formation of α-Fe(Si), Fe2B and Fe3(B,P) crystalline phases. VSM allowed to determine that the combination of chemical composition and microstructure with the best soft magnetic properties after the annealing corresponds with the alloy with 0.75% Cu. In addition, activation energy for glass transition and the first crystallization event were calculated using the Kissinger method. The research findings demonstrated that maintaining the relationship between the main elements, it is possible to keep the good glass forming ability with the possibility of developing a nanocrystalline structure with soft magnetic performance.Graphical abstract

Study of the dynamic fragility of polymer nanocomposites: Correlation with damping

AbstractIn this work, an extensive study on the glass transition temperature (Tg), dynamic fragility and activation energy (Ea) for a variety polymeric nanocomposite materials, based on four different types of polymeric matrices reinforced with carbonaceous nanofillers, and SiO2 has been performed. Referring to the dynamic mechanical analysis data obtained in the author's previous works, the dynamic fragility and activation energy were calculated and examined. Depending on the polymeric type, different behavior was detected, as far as the fragility dependence on nanofiller type and loading is concerned, whereas the Tg variation was also investigated. A general trend of a decreasing dynamic fragility with increasing Tg was found, with the exception of Polylactic acid (PLA)/hybrid nanocomposites. A relation between nanofillers synergy and dynamic fragility variation has been achieved, namely the more homogenous nanofillers dispersion (and the synergistic effect between nanofillers), was associated with higher dynamic fragility values. Furthermore, the inter‐particle distance increment may lead to an increased fragility and the Resin/SiO2 nanocomposites appear to follow this rule. In addition, strain sweep experiments were conducted to analyze the connection between fragility and damping of the polymer nanocomposites. The PLA/hybrid carbonaceous nanocomposites reveal an essential damping enhancement, associated with fragility lowering.

Structural and thermal characteristics of Ge30−xSbxTe10Se60 (0 ≤ x ≤ 20) glasses for electronic devices

Thermal characterization of different compositions of Ge30−xSbxTe10Se60 (x = 0, 5, 10, 15, 20 at.%) glassy materials has been investigated through differential scanning calorimetry (DSC). The tested glasses have been synthesized by melt-quench technique. Glassy materials display compositional phase separation at x = 0, 5, 10, 15 at.%. For additional increase in Sb content at x = 20 at.%, the separation of phases combines in the glass matrix. The glass transition temperature (Tg), initial temperature of crystallization (Tc), peak crystallization temperature (Tp) and melting temperature (Tm) were found to be affected by both heating rate and composition. It is noticed that the increasing of antimony mass percentage in the glassy matrix is leading to decrease in Tg, Tc, Tp and Tm values. The melting temperature (Tm) of these glasses was found in the range 733–746 K for the first phase and in the range 740–792 K for the second phase. The activation energy of glass transition (Eg), activation energy for crystallization (Ec), Avrami index (n) and fragility index (Fi) were calculated using these specific temperatures. Eg decreases with increasing Sb content in all studied samples, but Eg is increasing in the sample with Sb content of 20%, and hence, it varies between 102.7 and 110.6 kJ approximately, whereas (Ec) decreases with the increase in the Sb content in all the tested samples and varies between 283 and 339 kJ. The fragility index varies between 10 and 26 indicating that the melts of these glasses are strong, and the fragility is minimum. The results were discussed in terms of the average coordination number NC and chemical bond approach.

Investigation of Crystallization Kinetics of Na2ZnP2O7 Glass Using XRD and DTA Analysis

AbstractIn the present investigation, the crystallization kinetics of a glass with a molar composition 25Na2O‐25ZnO‐50P2O5 (NZPO) is studied by means of a non‐isothermal differential thermal analysis (DTA) and X‐ray diffraction (XRD) techniques. XRD pattern of the as‐synthesized glass indicates an amorphous glassy structure without additional crystalline phase. Moreover, the heat‐treated glass sample shows the crystallization of the Na2ZnP2O7 crystalline phase. The glass transition peak temperature increases with increasing heating rates and is ranged from 505.3 to 601.6 K. The crystallization shows the same behavior and the obtained values are ranged from 685.2 to 731.2 K. The activation energies for glass transition and crystallization are determined using different approaches and are in the range of 25.9–30.5 and 82.8–112.0 kJ mol−1, respectively. The n and m kinetic parameters are each close to 3.0, which indicates bulk nucleation process with 3D growth of crystals.

Non-isothermal crystallization kinetics study of sodium niobium phosphate glasses

Sodium niobium phosphate (SNP) glasses of composition xNb2O5–(50-x/2)Na2O–(50-x/2) P2O5 (x = 20, 30, 40 mol. %) are prepared by the conventional melt–quench technique. The non-isothermal kinetics of glass transition & crystallization of SNP glasses are studied by a differential scanning calorimeter (DSC). The dependence of glass transition temperature on the heating rate is used to deduce the activation energy of glass transition. The average activation energies of crystallization are calculated by model-free peak kinetic methods (Kissinger, Boswell, Augis-Bennet, and Ozawa). The local activation energies for crystallization with the volume fraction crystallized is estimated by linear iso-conversional methods (Kissinger-Akahira-Sunose, Starink, Tang, Flynn-Wall-Ozawa, and Various heating rates (VHR)) and by Friedman differential method. Avrami exponents are deduced to understand the nucleation and growth of various crystalline phases formed on heat treatment of SNP glasses. The change in the local Avrami exponent with the crystallized volume fraction confirms that the crystallization process occurs through volume nucleation, mainly with 3D growth. SEM analysis explored the crystalline morphologies and revealed the evolution of sheaf-like crystals.

Thermal stability and glass transition kinetics in GeTeSb glasses by using non-isothermal measurement

In this paper we have analysed the thermal properties of three different compositions of chalcogenide glasses Ge15Te85-xSbx (x=0.5, 1, 1.5). The samples have been prepared using the melt quenching technique and the characterisation is done using X-ray diffraction. The compositional dependence on properties were studied using Differential Scanning Calorimetry (DSC) analysis using non-isothermal measurement. The glassy sample crystallized by two transition temperatures Tg1 and Tg2.The dependence of glass transition temperature on heating rate has been studied by Lasocka empirical relation and the Kissinger equation. As a result, the apparent activation energy for glass transition has been determined. Thermal stability has also been determined from the temperature difference between the onset crystallization and glass transition temperature.

Evaluation of novel composition (SiO2–CaO–Na2O–P2O5, SrO–CuO) degradable amorphous silicate glasses properties and comprehensive characterization of the thermal features

The current work presents and discusses the findings of a comprehensive study on the structural, chemical and thermal properties of SrO and CuO incorporated SiO2–CaO–Na2O–P2O5 amorphous silicate glass with a novel composition. Here, fundamental features (experimental density, oxygen density, and hardness) of all glasses were determined and chemical as well as phase composition of the glasses was verified with XRF and XRD, respectively. Moreover, the thermal behavior (viscos flow and crystallization kinetics) of amorphous silicate glass was investigated by non-isothermal methods using DTA analysis. The activation energies of glass transition (Eg) were calculated in the range of 546–1115 kJ/mol by Kissinger method, whereas the activation energies of crystallization (Ec) were calculated in the range of 164–270 kJ/mol by three different methods (Kissinger, Ozawa, Yinnon and Uhlmann). Avrami exponent (n) values ranged from 1.17 to 3.28 demonstrated that amorphous silicate glasses have different crystallization mechanism. Working temperature, which is one of the parameters indicating glass stability, increased with the incorporation of Sr and Cu from 187 °C to 245 °C. The initial dissolution measurement has been applied to study the degradability behavior of Sr and Cu incorporated amorphous glasses in vitro. Quantitative evaluation of Si4+ (0.156–0.373 kV), Ca2+ (0.043–0.332 kV), Na+ (0.044–0.329 kV), P5+ (0.057–0.289 kV), Sr2+ (0.134–0.385 kV), and Cu2+ (0.090–0.203 kV) depending on the ion activation energy (Ea-ion) and ion concentration at different temperature values (24, 37 and 55 °C) was performed in contact with Tris-HCl solution by ICP-OES analysis. The results revealed that investigated glasses were degradable and incorporation of Sr and Cu affected the glass initial dissolution. Overall, investigated glasses are suitable for various application such as hot-working production, glass-ceramic manufacturing, and glass or glass-ceramic scaffolds fabrication, due to wide working temperature ranges and high crystallization tendencies of the developed glasses.

Theoretical and experimental studies of crystallization and glass transition kinetics of GeTeSe chalcogenide glass for PCM

Nanoscale phase-change materials (PCMs) are utilized as non-volatile next-generation storage class memory and other applications, and kinetics study becomes an important property for switching in high-temperature regimes. Glass transition kinetics and crystallization kinetics of GeTeSe0.5 glass has been studied theoretically and experimentally by employing differential scanning calorimetry (DSC). DSC curve was recorded on various heating rates (5,10,15,20 K/min). Glass transition activation energy switches as conversion fraction χg changes. The fragility index calculated for GeTeSe0.5 material shows that the composition belongs to strong glass-forming liquid. Theoretical developed model (TDM) and Johnson-Mehl-Avrami (JMA) model have been used for evaluating kinetic parameters. For studied composition, there is heterogeneous nucleation followed by two or three-dimensional crystal growth process by mean values of kinetic exponent factors. Results calculated by different models have been compared with experimental results and it has been noticed that TMD model satisfies with experimentally calculated values.

Amorphization and Crystallization of Hexanitroazobenzene (HNAB) Using Conventional DSC and Flash DSC

AbstractThe present work presents results from an investigation of the glass transition and crystallization behaviors of HNAB tested over more than five orders of magnitude of cooling rate from 0.005 °C/s to 600 °C/s (0.3 to 36000 °C/min) by a combination of conventional and Flash differential scanning calorimetry (DSC). The work quantifies the influence of the thermal amorphization route on the properties of this high explosive. Cooling rates faster than 100 °C/s (6000 °C/min) result in amorphous HNAB as expected from prior work, but we also find that amorphization of the HNAB occurs at cooling rates slower than 0.008 °C/s (0.5 °C/min). The behavior of the amorphous HNAB made by slow cooling is compared with that of amorphous HNAB made by fast cooling, as well as with that made by solvent casting in terms of glass transition temperature, apparent activation energy of glass transition, and dynamic fragility parameter m. Besides, the non‐isothermal crystallization response as a function of cooling rate is also reported. The thermal stability and decomposition energy of amorphous HNAB are compared with those of the crystalline counterpart, being similar heats of decomposition of 3295 and 3392 J/g, respectively; suggesting that the amorphous HNAB will have similar thermal stability and chemical energy to the crystalline form.

Crystallization evolution behavior of amorphous Fe85.7Si7.9B3.6Cr2C0.8 powder produced by a novel atomization process

Fe-Si-B amorphous alloy has the advantages of excellent soft magnetic properties, low magnetic loss, stable DC bias performance and strong corrosion resistance, etc. It is one of the commonly used raw materials for high-end electronic and electrical components. In this study, the thermodynamics and kinetics of the crystallization transition of high magnetic induction amorphous powder Fe85.7Si7.9B3.6Cr2C0.8 produced by a novel atomization process were investigated experimentally under non-isothermal and isothermal conditions based on DSC and XRD. The results show that the high Si contents in the amorphous composition and the eutectic reaction during initial crystallization stage lead to a structural transition between the ordered Fe-Si phases A2(α-Fe(Si)), B2(FeSi) and DO3(Fe3Si), thus resulting in the third exothermic peak of crystallization in the DSC curve of this system. In addition, the first exothermic peak of crystallization corresponding to the eutectic reaction is analyzed in detail in this paper. The crystallization process of the amorphous material is as follows: (a) Amorphous; (b) Amorphous+Fe3B+α-Fe(Si)+Fe3Si+Fe5Si3+FeSi; (c) Amorphous+ Fe3B+Fe2B+α-Fe(Si)+Fe3Si+Fe5Si3+FeSi; (d) Fe2B+α-Fe(Si)+Fe3Si+Fe5Si3+FeSi; (e) Fe2B+α-Fe(Si)+Fe3Si+Fe5Si3. And the undercooled liquid region of the amorphous powder is 52 K, the activation energy of glass transition is 396.73 kJ·mol−1, the activation energy of the first crystallization peak is 292.64 kJ·mol−1, and the fragility value is 27 belongs to strong metallic glass system. It also suggests that the amorphous materials have good thermal stability and glass forming ability (GFA).

Formation ability, thermal stability, and mechanical properties of the Zr50Cu34Al8Ag8 amorphous alloys prepared by different mold materials

In the present study, Zr50Cu34Al8Ag8 amorphous alloy rods with a diameter of 3 mm were prepared and the influence of the cooling capacity on the properties of cast samples was analyzed. To this end, three mold materials, including heat-resistant steel, copper, and high purity graphite were utilized. Then the amorphous structure, glass-forming ability, and thermal stability of the cast alloy were investigated using an X-ray diffractometer and differential scanning calorimeter. A universal testing machine was applied to investigate the mechanical properties of amorphous alloys with different mold materials. The fracture characteristics of the amorphous alloy were analyzed by scanning electron microscope, and the microstructures were analyzed using a high-resolution transmission electron microscope. The experimental results showed that among the studied cases, the highest glass-forming ability was achieved from the copper mold. Moreover, the glass transition and crystallization activation energies of the amorphous alloy obtained by suction casting of high-purity graphite mold were the largest, which were 525.8 kJ/mol and 334.0 kJ/mol, respectively, reflecting good thermal stability. Meanwhile, the performed analyses revealed that the fracture strength of the amorphous alloy and the corresponding strain were 1888.2 MPa and 3.55%, respectively, indicating that the cast sample has good mechanical properties. With the decrease of the cooling rate, the content of free volume in the amorphous alloy of high-purity graphite mold suction casting decreased, and the ordered structure was generated, which was the main reason for its high thermal stability and plastic deformation ability.

Crystallization resistance behavior of Al2O3-doped calcium bismuth borate glasses

Glass ceramic phosphors provide an effective solution to solve the problems of poor high thermal stability for current commercial WLEDs. The transmittance of sealing glass is one of the key factors to achieve high luminous performance of glass ceramic phosphors. In this work, a relative high transmittance and superior crystallization resistance frit seal of Al2O3-doped calcium bismuth borate glasses were successfully prepared. The crystallization resistance behaviors related to structures, morphologies were investigated. As increasing Al2O3 concentrations from 0 to 6 mol%, the glass structure becomes more compact. The capability of crystallization resistance and transmittance for the second sintering samples increase with increasing Al2O3 contents. 6 mol% Al2O3-doped glass exhibits virtually amorphous state and the transmittance is close to 70%. The glass transition activation energy (Eg) and crystallization activation energy (Ep) of glass sample with low Al2O3 content are about 382 kJ/mol and 280 kJ/mol and the precipitation of crystal phase possibly is Bi4B2O9. The YAG:Ce3+ glass ceramic prepared with 6 mol% Al2O3-doped glass yields a LE of 123.2 lm/W, a CCT of 5856 K and a CRI of 67.6. The as-prepared calcium bismuth borate glass with 6 mol% Al2O3 is a promising package material in the field of high-power WLEDs.

Physical characterization and crystallization kinetics of amorphous BiSe chalcogenide glasses

The influence of Bi concentration on the thermal parameters viz temperatures of glass transition (Tgl) and crystallization (Tpc) of binary BixSe100-x glasses were studied experimentally. The activation energy of glass transition (EGl) has been estimated as the averaged value deduced based on Kissenger's relationship and its approximation. On the other hand, Afify and Aly methods help one to estimate the crystallization activation energy (Epc), the frequency factor (k0) and the order of reaction (n) with no approximation. The observed increase in EGl and Epc values resulted from increasing both Tgl and Tpc with increasing of the Bi content. The Lasocka relationship can describe the heating rate dependence of Tgl and Tpc. A good correlation between Tgl and Tpc was investigated. The attained results were discussed according to the distribution of the chemical bonds, the main coordination number (Nr), average heats of atomization (Hs), the mean bond energy (Es), the cohesive energy (CE), and the overall average bond energy (<E>) for BixSe100-x glasses.

Modeling of thermal studies on melt quenched Ge18Bi4Se78 chalcogenide

The crystallization characteristics for Ge18Bi4Se78 glass are studied in this work by means of differential thermal analysis (DTA) under non-isothermal conditions. One stage endothermic glass transition and one exothermic crystallization are observed in the DTA curves. The results of topological constraints for Ge18Bi4Se78 glass show that the calculated value of glass transition temperature (Tg) is very close to that of the experimental results. The as-prepared, as well as the annealed samples, are examined using x-ray diffraction (XRD), energy dispersive x-ray spectroscopy (EDX), scan electron microscope (SEM) techniques. Avrami’s exponent (n) found to have an average value of 1.61 reveals a mixture of one dimensional and surface nucleation stages of growth. Many models are used to estimate the activation energies for glass transition (Eg) and crystallization (Ec). The crystallization process was found to be described by the Sestak- Berggren SB(M, N) model.