On the formation of intermetallics in Fe–Al system – An in situ XRD study

Novák, Pavel; Michalcová, Alena; Marek, Ivo; Mudrová, Martina; Saksl, K.; Bednarčı́k, J.; Zikmund, Petr; Vojtěch, Dalibor

doi:10.1016/j.intermet.2012.08.020

Cited by 88 publications

(49 citation statements)

References 30 publications

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“…• C. This change of the mechanism was also conrmed by in situ XRD analysis in our previous paper [5]. Microstructure variations of the FeAl25 alloy with the heating rate are displayed in Fig.…”

Section: Feal Systemsupporting

confidence: 80%

“…These reactions lead to the formation of Fe 2 Al 5 and FeAl 2 phases. These phases continuously transform to FeAl ordered phase when the temperature increases, as previously proved by in situ XRD [5]. On the other hand, at high heating rates aluminium melts preferentially.…”

Section: Feal Systemsupporting

confidence: 65%

“…The reason for choice of these systems lies in the presence of melt during the initiation of the reactions. In FeAl system, the formation of the melt before initiation was found by in situ X-ray diraction (XRD) in our previous paper [5], while in NiTi system the reactions initiate in solid state.…”

Section: Proceedings Of the International Symposium On Physics Of Matmentioning

confidence: 86%

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Effect of Heating Rate on the Formation of Intermetallics during SHS Process

et al. 2015

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Self-propagating high-temperature synthesis is a simple and ecient method for the synthesis of various compounds including ceramics and intermetallics. In this process, the compressed mixture of elemental or master alloy powders is ignited or heated to initiate the exothermic reactions leading to the formation of desired compounds. In order to control the process eciently, the eect of several important parameters has to be determined in each applied alloy system. Previous results showed that those parameters are: initiation temperature, process duration, pressure used for compression and heating rate. This paper is devoted to the description and explanation of the eect of the heating rate on the formation of intermetallics during self-propagating high-temperature synthesis in FeAl and NiTi systems. Dierential thermal analysis of compressed powder mixtures under various heating conditions and microstructure observation of samples prepared by various heating rates using electric resistance heating and spark plasma sintering were carried out. The eect of heating rates on the formations of intermetallics in studied systems is discussed in this paper.

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Section: Feal Systemsupporting

confidence: 80%

Section: Feal Systemsupporting

confidence: 65%

Section: Proceedings Of the International Symposium On Physics Of Matmentioning

confidence: 86%

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Effect of Heating Rate on the Formation of Intermetallics during SHS Process

et al. 2015

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“…The porosity increase in the case of iron aluminides was found to be connected with volume changes when the crystal lattice changes from iron to more complex structures of aluminides or silicides. In addition, Kirkendall effect was reported to play an important role [13]. The pores in all alloys are almost spherical and located predominantly in the centre of the sample.…”

Section: Experimental Materials and Conditionsmentioning

confidence: 93%

EFFECT OF ALLOYING ELEMENTS ON PROPERTIES OF PM Ti-Al-Si ALLOYS

Novák¹,

Kříž²,

Michalcová³

et al. 2013

Acta Metall Slovaca

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This work was devoted to the description of the effect of alloying by transition metals (Cr, Cu, Fe) on the structure and properties of TiAl15Si15 alloy. Alloying elements does not form separate phases, being dissolved in titanium silicide or aluminide. Cu was found predominantly in aluminide phase, while iron was found to bethe silicide-former. Chromium dissolved in both aluminide and silicide in almost comparable amounts. All applied alloying elements increased the wear resistance, but reduced the room-temperature compression strength. The addition of iron and chromium strongly increase the thermal stability at 1000°C by stabilizing the silicide phase.Keywords: reactive sintering; mechanical properties testing; intermetallic compounds; oxidation 1 Introduction Alloys based on titanium aluminides (Ti 3 Al and TiAl) are modern materials for hightemperature applications. Due to low density, good mechanical properties and oxidation resistance at high temperatures, these alloys already found its application in the aerospace industry. The application limits of Ti 3 Al phase are 760°C in inert atmosphere (creep limit) and approx. 600°C in air (oxidation limit) [1]. Application range of TiAl phase is 750°C in air and approx. 900°C in inert atmosphere or vacuum [1]. It shows that the temperature range of application of all Ti-Al phases is strongly limited by their high-temperature oxidation. To improve the high-temperature oxidation behaviour of these materials, additions of various alloying elements are applied. Previously, it was reported that niobium and tantalum increase the high-temperature oxidation resistance [2] and creep behaviour [3] of Ti-Al alloys. It led to the development of new generation of Ti-Al alloys [4]. However these heavy and expensive elements undesirably increase the density and cost. Other possibility how to improve hightemperature behaviour is alloying with silicon. When Ti-Al-Si alloys are produced by conventional melting metallurgy techniques, coarse sharp-edged particles of Ti 5 Si 3 silicide are formed, having negative impact on mechanical properties such as ductility or fracture toughness. Simple production route leading to the fine structure is a reactive sintering powder metallurgy. In our previous works [5], [6], production route for Ti-Al-Si alloys with aluminium content between 8 and 20 wt. % and silicon in the range of 10-20 wt. % was developed and roomtemperature properties were described [5]. There are many papers dealing with the influence of various alloying elements on the structure and selected properties of Ti-Al and Ti-Si binary alloys. In addition to the effect of Nb and Ta,

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“…Foramsi lapisan intermetallic yang semakin terbal, menyebabkan kegetasan sambungan meningkat [10]. Formasi intermetallic yang bersifat getas ini mulai terbentuk pada temperatur di bawa temperatur leleh aluminium dengan terdifusinya atom-atom aluminium pada Fe [11].…”

Section: Gambar 13 Foto Mikro Pada Batas Sambungan Dengan Tekanan Geunclassified