G. A. Pribytkov, A. V. Baranovskiy, V. V. Korzhova, I. A. Firsina, V. P. Krivopalov
{"title":"Synthesis of Ti–Fe Intermetallics from Element Powder Mixtures","authors":"G. A. Pribytkov, A. V. Baranovskiy, V. V. Korzhova, I. A. Firsina, V. P. Krivopalov","doi":"10.1134/S0036029525700600","DOIUrl":null,"url":null,"abstract":"<p><b>Abstract</b>—Fe<sub>2</sub>Ti and FeTi intermetallic compounds are of practical use as either hydrogen storages (FeTi) or magnetic materials (Fe<sub>2</sub>Ti). Owing to features of the equilibrium binary phase diagram, the preparation of the intermetallics by casting is difficult. Therefore, powder metallurgy methods along with preliminary mechanical activation of powder mixtures are widely used. The aim of the study is to investigate the possibility of preparation of single-phase compounds from titanium and iron powder mixtures having target compositions. Mechanically activated powder mixtures and products of combustion and subsequent annealing are studied by X-ray diffraction analysis, optical metallography, and scanning electron microscopy and energy dispersive spectroscopy used for the determination of the element composition. Powder mixtures are subjected to 20‑min mechanoactivation in an Activator 2S planetary mill at an intensity of 40 <i>g</i>; the ball-to-mixture ratio is 20. The mechanically activated mixtures are heated in a hermetically sealed reactor in an argon atmosphere at an average rate of 85 deg/min. Thermal curves, which are measured with thermocouples placed into a mechanoactivated mixture, demonstrate an abrupt rise (thermal explosion (TE)), which corresponds ~500°C and indicates the occurrence of an exothermic reaction in the mixture. The 2Fe + Ti composition is found to indicate the substantially higher rise as compared to that observed for the Fe + Ti composition. X-ray diffraction analysis shows that the Fe<sub>2</sub>Ti compound is the main reaction product for the both mixtures. The dominant formation of Fe<sub>2</sub>Ti and the high thermal effect of the 2Fe + Ti mixture as well are explained by the higher negative enthalpy of formation of Fe<sub>2</sub>Ti as compared to that of FeTi (–87.45 and –40.58 kcal/mol, respectively). High temperature homogenizing annealing of TE products results in the formation of a double-phase target product. After annealing, the contents of side phases and unreacted reagents slightly change. Based on the obtained data, it is inferred that the thermodynamic factor (enthalpy of formation of intermetallic) is the main factor determining the phase composition of the synthesis products in titanium and iron powder mixtures.</p>","PeriodicalId":769,"journal":{"name":"Russian Metallurgy (Metally)","volume":"2024 12","pages":"1980 - 1986"},"PeriodicalIF":0.4000,"publicationDate":"2025-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Russian Metallurgy (Metally)","FirstCategoryId":"5","ListUrlMain":"https://link.springer.com/article/10.1134/S0036029525700600","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"METALLURGY & METALLURGICAL ENGINEERING","Score":null,"Total":0}
引用次数: 0
Abstract—Fe2Ti and FeTi intermetallic compounds are of practical use as either hydrogen storages (FeTi) or magnetic materials (Fe2Ti). Owing to features of the equilibrium binary phase diagram, the preparation of the intermetallics by casting is difficult. Therefore, powder metallurgy methods along with preliminary mechanical activation of powder mixtures are widely used. The aim of the study is to investigate the possibility of preparation of single-phase compounds from titanium and iron powder mixtures having target compositions. Mechanically activated powder mixtures and products of combustion and subsequent annealing are studied by X-ray diffraction analysis, optical metallography, and scanning electron microscopy and energy dispersive spectroscopy used for the determination of the element composition. Powder mixtures are subjected to 20‑min mechanoactivation in an Activator 2S planetary mill at an intensity of 40 g; the ball-to-mixture ratio is 20. The mechanically activated mixtures are heated in a hermetically sealed reactor in an argon atmosphere at an average rate of 85 deg/min. Thermal curves, which are measured with thermocouples placed into a mechanoactivated mixture, demonstrate an abrupt rise (thermal explosion (TE)), which corresponds ~500°C and indicates the occurrence of an exothermic reaction in the mixture. The 2Fe + Ti composition is found to indicate the substantially higher rise as compared to that observed for the Fe + Ti composition. X-ray diffraction analysis shows that the Fe2Ti compound is the main reaction product for the both mixtures. The dominant formation of Fe2Ti and the high thermal effect of the 2Fe + Ti mixture as well are explained by the higher negative enthalpy of formation of Fe2Ti as compared to that of FeTi (–87.45 and –40.58 kcal/mol, respectively). High temperature homogenizing annealing of TE products results in the formation of a double-phase target product. After annealing, the contents of side phases and unreacted reagents slightly change. Based on the obtained data, it is inferred that the thermodynamic factor (enthalpy of formation of intermetallic) is the main factor determining the phase composition of the synthesis products in titanium and iron powder mixtures.
期刊介绍：
Russian Metallurgy (Metally) publishes results of original experimental and theoretical research in the form of reviews and regular articles devoted to topical problems of metallurgy, physical metallurgy, and treatment of ferrous, nonferrous, rare, and other metals and alloys, intermetallic compounds, and metallic composite materials. The journal focuses on physicochemical properties of metallurgical materials (ores, slags, matters, and melts of metals and alloys); physicochemical processes (thermodynamics and kinetics of pyrometallurgical, hydrometallurgical, electrochemical, and other processes); theoretical metallurgy; metal forming; thermoplastic and thermochemical treatment; computation and experimental determination of phase diagrams and thermokinetic diagrams; mechanisms and kinetics of phase transitions in metallic materials; relations between the chemical composition, phase and structural states of materials and their physicochemical and service properties; interaction between metallic materials and external media; and effects of radiation on these materials.
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