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BHM (2014) Vol. 159 (1): 5–11DOI 10.1007/s00501-013-0226-9© Springer-Verlag Wien 2013

Early Stages of Precipitation: Experiments and Modelling

Sophie Primig1, Harald Leitner1,2 and Ernst Kozeschnik3

1 Christian Doppler Laboratory Early Stages of Precipitation, Department of Physical Metallurgy and Materials Testing, Montanuniversität Leoben, Leoben, Austria

2Böhler Edelstahl GmbH & Co KG, Kapfenberg, Austria3 Christian Doppler Laboratory Early Stages of Precipitation, Institute of Materials Science and Technology, Vienna University of Technology, Vienna, Austria

Frühe Stadien der Ausscheidungsbildung – Experimente und Modellierung

Zusammenfassung: Ausscheidungshärtung von me-tallischen Hochleitungswerkstoffen wird als einer der wichtigsten Härtungsmechanismen betrachtet. In Legie-rungen mit Elementen, die Ausscheidungsbildner sind, können sich fein verteilte, nanometer-kleine Teilchen aus einem gesättigten Mischkristall ausscheiden. Die Grö-ße, Volumensfraktion und Anzahl dieser Teilchen können durch kontrolliertes thermomechanisches Umformen oder durch eine gezielte Wärmebehandlung eingestellt werden. Das Christian Doppler Labor „Early Stages of Precipitation“ möchte ein tieferes Verständnis über Aus-scheidungsbildung in Stählen, Nickelbasislegierungen und Refraktärmetallen aufbauen. Der experimentelle Teil des Labors in Leoben konzentriert sich auf die Charak-terisierung von kleinsten Ausscheidungen mittels mo-derner, hochauflösender Methoden wie Atomsonde, Durchstrahlungselektronenmikroskopie, Streumethoden und thermischer Analyse. Der theoretische Teil des Labors in Wien beschäftigt sich mit der kinetischen Modellierung von Ausscheidungsreaktionen, vor allem im Rahmen der Weiterentwicklung der Software „MatCalc“. Das gemein-same Ziel beider Teile ist der Aufbau eines umfassenden Verständnisses über Mikrostruktur-Eigenschaftsbeziehun-gen, um in Zukunft ausscheidungsgehärtete Legierungen mit verbesserten mechanischen Eigenschaften entwickeln zu können.

Schüsselwörter: Ausscheidungsbildung, Thermomecha-nisches Umformen, Wärmebehandlung, Atomsonde, Transmissionselektronenmikroskopie, Modellierung

Abstract: Precipitation hardening of structural high-per-formance materials is considered as one of the most im-portant strengthening mechanisms. In alloys containing precipitate forming elements, a fine dispersion of nano-meter-sized particles precipitates from a supersaturated solid-solution. The size, volume fraction, and number density of these precipitates can be controlled by elabo-rate thermo-mechanical processing or by thermal treat-ments. The Christian Doppler Laboratory “Early Stages of Precipitation” aims at establishing a deeper understand-ing of such precipitation processes in steels, nickel-base alloys, and refractory metals. The experimental part of the lab in Leoben focuses on the characterization of small precipitates by state-of-the art high-resolution methods such as atom probe tomography and transmission elec-tron microscopy, by scattering techniques, and by ther-mal analysis. The modelling part in Vienna concentrates on the modelling of precipitation kinetics mostly within the framework of the scientific software “MatCalc”. The main objective of both parts is the comprehensive study of the microstructure-property relationship in order to develop particle strengthened alloys with improved me-chanical properties.

Keywords: Precipitation, Thermo-mechanical processing, Heat treatment, Atom probe tomography, Transmission electron microscopy, Modelling

Dr. S. Primig ()Christian Doppler Laboratory Early Stages of Precipitation, Department of Physical Metallurgy and Materials Testing,Montanuniversität Leoben, Franz-Josef Straße 18,8700 Leoben, Austriae-mail: sophie.primig@unileoben.ac.at

Received November 18, 2013; accepted December 10, 2013; published online January 10, 2014

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1. Introduction to the Lab

The Christian Doppler Laboratory “Early Stages of Pre-cipitation” (CDL ESOP) focuses on the advanced study of precipitation phenomena in high-performance materials, such as steels, nickel-base, and refractory metals. These materials owe their superior mechanical properties to a microstructure with specific characteristics, such as a small grain size, a high dislocation density, and the pres-ence of particles or clusters of particular atoms, i.e. precip-itates. Precipitation hardening is considered as one of the most important strengthening mechanisms in advanced materials [1]. It can be controlled by elaborate thermo-mechanical processing or by thermal treatments such as quenching and tempering of steels [2]. The improvement of conventional materials and development of new materi-als in collaboration with our industry partners, therefore, requires a deep understanding of precipitation reactions and their influence on the resulting mechanical properties.

Precipitation reactions in advanced multi-component materials are characterized by complex interactions between the individual alloying elements. To study these processes, the extensive analysis of the kinetics of precipi-tation is essential. The spatial extension and amplitude of compositional fluctuations of incipient second-phase par-ticles as well as their morphology, number density, size, and chemical composition at various stages of the reac-tion have to be studied in detail. For this purpose, high-resolution techniques are required which are capable of resolving very small—typically a few nm—solute clusters and which allow an analysis of their chemical composi-tion and crystallography. The most prominent tools meet-ing these requirements are atom probe tomography [3, 4] and transmission electron microscopy [5] (direct investi-gation methods) as well as small-angle scattering [6] and differential-scanning-calorimetry [7] (indirect investigation methods). These experimental techniques are applied in a complementary way in the CDL ESOP to complete the understanding of the precipitation process, since none of these techniques alone can provide the entire information required.

The state-of-the-art experimental approach for the study of precipitation processes is combined with advanced computer simulation tools to verify the experi-ments on simulation and vice versa. In addition to tradi-tional thermodynamic equilibrium tools (‘Computational Thermodynamics’), a novel approach for the simulation of the precipitation kinetics in multi-component multi-phase multi-particle systems (Software MatCalc [8]) is applied to study the evolution of the microstructure and the precipi-tates on the researchers desktop [9–11]. With the simulated precipitation kinetics, predictions on the strengthening effect of precipitates are attempted and compared to exper-imental data on the evolution of the mechanical properties in the course of thermal or thermo-mechanical treatments. Only the combination of both, theoretical and experimen-tal approach, allows a complete and comprehensive char-acterization of microstructural transformations and the prediction of the resulting mechanical properties.

2. History and Structure of the CDL ESOP

The CDL ESOP is divided into two modules (Module A, the experimental part in Leoben, and Module B, the modelling part, which started in Graz and moved to Vienna in 2008). An overview over the modules of the CDL ESOP is shown in Fig. 1. The structure of the lab, the materials of interest, their suppliers, the history of the lab as well as some fur-ther success stories will be summarized in the following.

2.1 Module A (Microstructure-Properties)

In order to characterize small precipitates in detail, high-resolution methods, such as transmission electron microscopy (TEM) and atom probe tomography (APT), are applied as direct investigation methods due to the pos-sibility of directly imaging the particles. In order to gain more statistically confident information on size, volume fraction, and distribution of particles, methods, which probe a significantly larger sample volume than TEM and APT, are applied additionally. Such methods are differen-tial scanning calorimetry (DSC) and small-angle scattering (SAS) techniques. They are called indirect investigation methods because they are not capable of directly imaging the particles.

TEM is a well-established technique and widely used for second-phase analyses [12, 13]. It offers the possibility to study the crystallographic nature of both, matrix and par-ticles, and to determine the size and shape of the prevail-ing particles. Supplementary techniques, such as energy dispersive X-ray spectroscopy (EDS), can be used to deter-mine their chemical composition [5]. APT is nowadays rec-ognized as the major analytical technique in the field of physical metallurgy, especially for the characterization of nm-sized precipitates. Recent developments of APT give access to three-dimensional imaging and chemical analy-sis of materials down to the atomic level [3, 4, 14]. APT is especially suitable for investigating the initial stages of a

Fig. 1: Overview over the structure and the project modules of the CDL ESOP

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corresponding microstructural features in order to improve our understanding of the microstructure-property relation-ship. These findings are also used to advance or validate existing models which describe the macroscopic mechani-cal behaviour of high-performance materials [24–27].

2.2 Module B (Modelling and Simulation)

In the CDL ESOP, the thermo-kinetic software “MatCalc”, which contains novel and powerful theoretical models for multi-component, multi-phase precipitation kinetics, is our central modelling and simulation tool. MatCalc was started by Ernst Kozeschnik in 1994 as a part of his Ph.D. project at the Graz University of Technology. Since 1994, it has evolved into a software project for computer simu-lation of phase transformations in metallic systems. The thermodynamic foundation of MatCalc is the CALPHAD method and (unencrypted) CALPHAD-type databases. The kinetic modules of MatCalc are developed within the framework of solid-state phase transformations, with par-ticular focus on computational efficiency and applicability to multi-component systems [11, 28–30].

In the research performed at the CDL ESOP, the theoreti-cal approaches used in MatCalc are extended and critically verified on the experimental data generated in the work done in Module A [31].

The software MatCalc is used as a simulation tool for predicting the evolution of the precipitates and the microstructure during thermal and thermo-mechanical processing of the materials of our industry partners. The simulations include case studies and parameter varia-tions in order to optimize the production strategies of their industrial processes [32, 33].

2.3 Materials and Industry Partners

In the CDL ESOP, we investigate nickel-base alloys, tool steels, high-strength-low-alloy (HSLA) steels, and refrac-tory metals. Table  1 summarizes our different engineer-ing high-performance materials as well as their nm-sized microstructural constituents and their suppliers, our six Austrian company partners. A common feature of our four groups of engineering high-performance materials is that their mechanical and thermo-physical properties are essentially determined by the presence of different types of nm-sized precipitates.

precipitation process where the particles exhibit a size of a few nm and, thus, are not easily accessible by TEM [15–18]. Another advantage of APT, when compared to chemical analysis by EDS in the TEM, is its equal detection efficiency for all elements due to the principle of time-of-flight detec-tion. We are especially proud of our two state-of-the-art APT instruments (the LEAP 3000x HR is shown in Fig. 2) at the Department of Physical Metallurgy and Materials Test-ing in Leoben, which are unique in Austria.

DSC is a thermo-analytical technique in which the dif-ference in the amount of heat required to increase the temperature of a sample and a reference material are measured as a function of temperature and heating rate [7]. When the sample undergoes a phase transformation, such as the formation of precipitates, more (or less) heat is necessary to maintain the sample at the same temperature when compared to the reference material. The result is a peak in the DSC curve. The obtained curve can be used to determine kinetics of precipitation reactions and the reac-tion enthalpy [19, 20]. Small-angle scattering (SAS) is the collective name given to the techniques of neutron (SANS) and X-ray (SAXS) scattering. SANS and SAXS are the most powerful methods for investigating three-dimensional chemical heterogeneities and density fluctuations with sizes of about 1 nm to 100 nm [17, 21–23]. Carefully inter-preted, SANS and SAXS data can give statistically mean-ingful information on particle size distributions, which complements the data obtained by microscopic methods.

The mechanical properties (e.g. hardness, strength, and toughness) of our materials are related to the

TABLE 1:

Materials studied in the CDL ESOP with types of precipitates and suppliers

Material Type of precipitates Supplier

Nickel-base alloys e.g., δ (Ni3Nb(Ti, Al)), γ’(Ni3Al(Ti, Nb)), γ”(Ni3Nb(Ti, Al)), (Nb, Ti)(C, N), Cr(Mo, Ni)

23C6, Mo(Cr)3BBöhler Schmiedetechnik GmbH & Co KG

Tool steels e.g., M2C, MC, M7C3, M23C6, M6C, NiAl, Ni3Al, Ni3Ti, Cu Böhler Edelstahl GmbH & Co KG

HSLA steels Mainly MX, with M = V, Nb,Ti, Al and X = C, N voestalpine Stahl Donawitz GmbH & Co KGAustria Draht GmbH DonawitzStahl Judenburg GmbH

Refractory metals (Ti, Zr)C, HfC Plansee SE

Fig. 2: LEAP 3000x HR atom probe by Cameca at the Department of Physical Metallurgy and Materials Testing, Montanuniversität Leoben

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Post-Doc. in the CDL ESOP successfully applied for Harald Leitner’s position at the university and is, therefore, still indirectly with CDL ESOP. In 2013, Ernst Kozeschnik fin-ished his book titled “Modeling Solid-State Precipiation” [11]. Even though Harald Leitner moved to the industrial side of CDL ESOP, several promising projects are still on-going in Leoben and Vienna. Our alumni are successful in industry and academia in Austria and all over the world (e.g. our former Post-Doc. Mehran Maalekian is now in Canada).

In September 2012, when the second scientific evalua-tion took place, the CDL ESOP had close to 60 articles in refereed journals and 16 conference proceedings. Besides that, 3 Master theses and 5 Ph.D. theses have been fin-ished until today. More are about to follow.

3. Experiment and Modelling—Research Highlights

In the following parts, two outstanding research highlights are presented. With these examples we intend to demon-strate how experiment and modelling are applied in CDL ESOP as complementary techniques with great success.

3.1 Reverted Austenite and NiAl Precipitation in a PH 13-8 Maraging Steel

The properties of maraging steels are determined by the martensitic substructure, on the one hand, and by a high density of nanometer sized precipitates, on the other hand. While aging at 575 °C, reverted austenite forms in addi-tion to the precipitation of B2-type NiAl particles [24, 34]. Figure 3 shows a three-dimensional APT reconstruction of the atomic positions of a PH 13–8 maraging steel aged for 100 h at 575 °C [34]. The left image displays the measured volume, while the rectangle on the right provides a detail of this volume with the reconstruction of atom positions of Ni, Al, and Cr. Figure 3 shows that the analyzed volume con-sists of different enriched areas, corresponding to different phases. There are Ni-enriched areas on top and bottom of

Some nickel-base alloys, so-called superalloys, belong to the group of structural high-performance materials exhibiting superior high-temperature properties. Conse-quently, this group of materials is mainly used for heavy-duty parts and components for gas turbines, aerospace engines, combustion engines, nuclear reactors, and pumps [22, 23].

Steels required for processing and machining of mate-rials are called tool steels. Depending on the work-tem-perature and the corresponding microstructure, tool steels are divided into cold-work tool steels, hot-work tool steels, and high-speed steels [16, 18, 34, 35].

HSLA (high strength low alloy) steels are impor-tant materials for structural components. The excellent mechanical properties of these steels are achieved with minimum alloying costs, because advantage is taken of the effect of strong carbide and nitride forming elements, such as V, Nb, or Ti and interface active elements such as B or Nb [12, 36].

Molybdenum, tungsten, and tantalum alloys are used as high temperature materials due to their high melting points above 2000 °C for, e.g. casting and forging dies, lighting technology and high temperature furnace con-struction. In addition, they are applied at ambient temper-atures as high-performance materials in electronics and coating technology [37–39].

2.4 History and Success Stories

The CDL ESOP launched its activities in September 2007 at the Montanuniversität Leoben and at the Graz Univer-sity of Technology. The two founders and heads of the CDL ESOP were Harald Leitner (Leoben) and Ernst Koz-eschnik (Graz). In the same year, the second atom probe was installed in Leoben (LEAP 3000x HR). In 2008, the Modelling and Simulation part of the CDL ESOP (Module B) moved to Vienna University of Technology with Ernst Kozeschnik, who was appointed professor at the Institute of Materials Science and Technology. The CDL ESOP has three Ph.D. and one Post-Doc. positions for studying pre-cipitation phenomena experimentally in Leoben and one full-time and one part time Ph.D. and one Post-Doc. posi-tion for the corresponding modelling in Vienna. In 2009 and in 2012, the two year and five year evaluations of the CDL ESOP were passed with great success. In 2011, Ronald Schnitzer finished his Ph.D. studies in the CDL ESOP “sub auspiciis praesidentis”. A new type of steel, which is now available at our partner company Böhler Edelstahl GmbH & Co KG, was developed in the course of this thesis. In 2012, the Department of Physical Metallurgy and Materi-als Testing purchased a FEI Versa 3D Focused Ion Beam, which now allows the site-specific specimen preparation for, e.g. APT. In the same year, Harald Leitner finished his Habilitation thesis titled “Physical Metallurgy of Cor-rosion Resistant Maraging Steels”. However, in 2013, he left the university for one of our industry partners, Böhler Edelstahl GmbH & Co KG, where he is currently head of research. Sophie Primig, who did her Ph.D. on the thermo-mechanical processing of refractory metals and one year

Fig. 3: Three-dimensional reconstruction of a PH 13-8 maraging steel aged at 575 °C for 100 h. The rectangle shows a detail of the detected volume and the distribution of Ni, Al, and Cr atoms [34]

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The proposed strengthening equations are functions of the size and distribution of Y’, which were determined experimentally by complementary high-resolution TEM investigations of isothermal aging at 788 °C [13, 41]. Figure 6 shows TEM dark field images of Allvac® 718PlusTM after aging at 788 °C for 1, 10, and 50  hours, which evi-dence the coarsening behavior of the Y’ precipitates.

4. Summary and Outlook

The present article highlights activities of the CDL ESOP in its effort to establish a deeper understanding of precipi-tation processes in steels, nickel-base alloys, and refrac-tory metals by combining experiments and modelling in a complementary approach. The structure of the lab, the materials we study, their providers, and our history is described, and two examples aimed at demonstrating how experiments and modelling can be combined suc-cessfully are introduced.

the volume, representing reverted austenite. In between a region with a lower Ni content, the martensitic matrix is vis-ible, which contains small spherical NiAl precipitates. The Ni content within the austenite phase was determined to be about 14 at.%, whereas the Al content remains almost the same as in the martensitic matrix. Furthermore, it is obvi-ous that the austenite phase is free of precipitating phases that cause strengthening. Only carbides of the type (Cr, Mo)2C were found to precipitate at the interface between martensite and austenite as well as inside the austenite.

The simulations in this project were aimed at under-standing the mechanism of precipitation and the interaction between the reverted austenite formation and B2-ordered NiAl precipitation. The first step of the theoretical investi-gation was the reassessment of the thermodynamic data for the phase equilibrium between the martensitic matrix, reverted austenite, and NiAl precipitates. In the next step, the software MatCalc was used to simulate the precipita-tion kinetics of austenite and NiAl from the supersaturated martensite [40]. Figure 4 shows exemplarily some results of these simulations together with experimental data obtained in the project in Module A.

3.2 Simulation of the Yield Strength in the Ni Base Alloy Allvac® 718PlusTM

The formation of Y’ (Ni3Al(Ti, Nb)) precipitates during aging causes the major effect on the final yield strength of the Ni base alloy Allvac® 718PlusTM [22, 23, 31]. The distribution of the Y’ precipitates is a consequence of the applied thermal treatment. We developed a comprehen-sive and consistent physical model for the yield strength increment in Allvac® 718PlusTM caused by precipitation strengthening [41]. The model incorporates the effect of different shearing and non-shearing mechanisms of dis-location—precipitate interaction. We demonstrated that coherency and anti-phase boundary effects are the major strengthening mechanisms in this alloy. The simulation result of strengthening by the coherency effect and the contribution of all strengthening components in the final yield strength is shown in Fig. 5.

Fig. 5: Simulation result of strengthening a coherency effect and b contribution of all strength-ening components in the final yield strength during aging of Allvac® 718PlusTM [41]

Fig. 4: Thermo-kinetic simulation showing the phase fraction of NiAl precipitates and reverted austenite (aging temperature = 575 °C) in a PH13-8 maraging steel [34]

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15. Leitner, H.; Schober, M.; Schnitzer, R.: Splitting phenomenon in the precipitation evolution in an Fe–Ni–Al–Ti–Cr stainless steel, Acta Materialia, 58 (2010), pp. 1261–1269

16. Leitner, H.; Schnitzer, R.; Schober, M.; Zinner, S.: Precipitate modi-fication in PH 13–8 Mo type maraging steel, Acta Materialia 59, (2011), pp. 5012–5022

17. Schober, M.; Eidenberger, E.; Leitner, H.; Staron, P.; Reith, D.; Pod-loucky, R.: A critical consideration of magnetism and composition of (bcc) Cu precipitates in (bcc) Fe, Applied Physics, A 99 (2010), pp. 697–704

18. Lerchbacher, C.; Zinner, S.; Leitner, H.: Atom probe study of the carbon distribution in a hardened martensitic hot-work tool steel X38CrMoV5–1, Micron, 43 (2012), pp. 818–826

19. Primig, S.; Leitner, H.: Transformation from continuous-to-isother-mal aging applied on a maraging steel, Materials Science and Engineering, A 527 (2010), pp. 4399–4405

20. Primig, S.; Leitner, H.: Separation of overlapping retained aus-tenite decomposition and cementite precipitation reactions dur-ing tempering of martensitic steel by means of thermal analysis, Thermochim Acta, 526 (2011), pp. 111–117

21. Eidenberger, E.; Schnitzer, R.; Zickler, G. A; Schober, M.; Bischof, M.; Staron, P.: Application of Photons and Neutrons for the Char-acterization and Development of Advanced Steels, Advanced Engineering Materials, 13 (2011), pp. 664–673

22. Zickler, G. A.; Schnitzer, R.; Radis, R.; Hochfellner, R.; Schweins, R.; Stockinger, M.; Leitner, H.: Microstructure and mechanical proper-ties of the superalloy ATI Allvac® 718PlusTM, Materials Science and Engineering, A 523 (2009), pp. 295–303

23. Zickler, G. A.; Radis, R.; Schnitzer, R.; Kozeschnik, E.; Stockinger, M.; Leitner, H.: The Precipitation Behavior of Superalloy ATI Allvac 718Plus, Advanced Engineering Materials, 12 (2010), pp. 176–183

24. Schnitzer, R.; Zickler, G. A.; Lach, E.; Clemens, H.; Zinner, S.; Lippmann, T.; Leitner, H.: Influence of reverted austenite on static and dynamic mechanical properties of a PH 13–8 Mo mar-aging steel, Materials Science and Engineering, A 527 (2010), pp. 2065–2070

25. Schnitzer, R.; Zinner, S.; Leitner, H.: Modeling of the yield strength of a stainless maraging steel, Scripta Materialia, 62 (2010), pp. 286–289

26. Leitner, H.; Schober, M.; Schnitzer, R.; Zinner, S.: Strengthening behavior of Fe–Cr–Ni–Al–(Ti) maraging steels, Materials Science and Engineering, A 528 (2011), pp. 5264–5270

27. Holzer, I.; Kozeschnik, E.: Computer simulation of the yield strength evolution in Cu-precipitation strengthened ferritic steel, Materials Science and Engineering, A 527 (2010), pp. 3546–3551

28. Maalekian, M.; Kozeschnik, E.: A thermodynamic model for car-bon trapping in lattice defects, Calphad, 32 (2008), pp. 650–654

29. Sonderegger, B.; Kozeschnik, E.: Generalized Nearest-Neighbor Broken-Bond Analysis of Randomly Oriented Coherent Interfaces in Multicomponent Fcc and Bcc Structures, Metallurgical and Materials Transactions, A 40 (2009), pp. 499–510

30. Kozeschnik, E.; Svoboda, J.; Radis, R.; Fischer, F. D.: Mean-field model for the growth and coarsening of stoichiometric precipi-tates at grain boundaries, Modelling and Simulation in Materials Science and Engineering, 18 (2010), p. 015011

31. Radis, R.; Schaffer, M.; Albu, M.; Kothleitner, G.; Pölt, P.; Koze-schnik, E.: Multimodal size distributions of γ’ precipitates during continuous cooling of UDIMET 720 Li, Acta Materialia, 57 (2009,) pp. 5739–5747

During the last six years, we have been able to carry out numerous fruitful scientific projects in collaboration with our six Austrian industry partners. We have still one year left for our lab to go. However, we assume that the suc-cess story of precipitation experiments and modelling will continue far beyond the time of CDL ESOP.

5. Acknowledgements

The financial support by the Austrian Federal Ministry of Economy, Family and Youth and the National Foundation for Research, Technology and Development is gratefully acknowledged.

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Fig. 6: TEM dark field images of Allvac® 718PlusTM after aging at 788 °C for a 1 h. b 10 h. c 50 h [41]

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37. Babinsky, K.; Primig, S.; Knabl, W.; Lorich, A.; Weingärtner, T.; Wei-dow J.; et al.: Grain boundary segregations in technically pure molybdenum, Proceedings of the 18th Plansee Seminar, Plansee SE, 2013, p. RM111/1–15

38. Primig, S.; Leitner, H.; Knabl, W.; Lorich, A.; Clemens, H.; Stick-ler, R.: Textural Evolution During Dynamic Recovery and Static Recrystallization of Molybdenum, Metallurgical and Materials Transactions, A 43 (2012), pp. 4794–805

39. Pöhl, C.; Lang, D.; Schatte, J.; Leitner, H.: Strain induced decom-position and precipitation of carbides in a molybdenum–haf-nium–carbon alloy, Journal of Alloys and Compounds, 579 (2013), pp. 422–431

40. Povoden-Karadeniz, E.; Kozeschnik, E.: Simulation of Precipita-tion Kinetics and Precipitation Strengthening of B2-precipitates in Martensitic PH 13–8 Mo Steel, ISIJ International, 52 (2012), pp. 610–615

41. Ahmadi, M. R.; Whitmore, L.; Povoden-Karadeniz, E.; Stockinger, M.; Falahati, A.; Kozeschnik, E.: Simulation of yield strength in All-vac® 718PlusTM, Proceedings of Thermec, 2013

32. Zamberger, S.; Pudar, M.; Spiradek-Hahn, K.; Reischl, M.; Koz-eschnik, E.: Numerical simulation of the evolution of primary and secondary Nb(CN), Ti(CN) and AlN in Nb-microalloyed steel during continuous casting, International Journal of Materials Research, 103 (2012), pp. 680–687

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