Microstructure and mechanical properties of nano-Y2O3 dispersed ferritic steel synthesized by mechanical alloying and consolidated by pulse plasma sintering |
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Authors: | SK Karak J Dutta Majumdar W Lojkowski A Michalski L Ciupinski KJ Kurzydłowski |
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Institution: | 1. Metallurgical and Materials Engineering Department , Indian Institute of Technology , Kharagpur 721302 , India;2. Metallurgical and Materials Engineering Department , National Institute of Technology , Rourkela 769008 , India;3. Metallurgical and Materials Engineering Department , Indian Institute of Technology , Kharagpur 721302 , India;4. Institute of High Pressure Physics (Unipress), Polish Academy of Sciences , Sokolowska 29 , 01-142 Warsaw , Poland;5. Faculty of Materials Science and Engineering , Warsaw University of Technology , Wo?oska 141 , 02-507 Warsaw , Poland |
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Abstract: | Ferritic steel with compositions 83.0Fe–13.5Cr–2.0Al–0.5Ti (alloy A), 79.0Fe–17.5Cr–2.0Al–0.5Ti (alloy B), 75.0Fe–21.5Cr–2.0Al–0.5Ti (alloy C) and 71.0Fe–25.5Cr–2.0Al–0.5Ti (alloy D) (all in wt%) each with a 1.0?wt% nano-Y2O3 dispersion were synthesized by mechanical alloying and consolidated by pulse plasma sintering at 600, 800 and 1000°C using a 75-MPa uniaxial pressure applied for 5?min and a 70-kA pulse current at 3?Hz pulse frequency. X-ray diffraction, scanning and transmission electron microscopy and energy disperse spectroscopy techniques have been used to characterize the microstructural and phase evolution of all the alloys at different stages of mechano-chemical synthesis and consolidation. Mechanical properties in terms of hardness, compressive strength, yield strength and Young's modulus were determined using a micro/nano-indenter and universal testing machine. All ferritic alloys recorded very high levels of compressive strength (850–2850?MPa), yield strength (500–1556?MPa), Young's modulus (175–250?GPa) and nanoindentation hardness (9.5–15.5?GPa), with up to 1–1.5 times greater strength than other oxide dispersion-strengthened ferritic steels (<1200?MPa). These extraordinary levels of mechanical properties can be attributed to the typical microstructure of uniform dispersion of 10–20-nm Y2Ti2O7 or Y2O3 particles in a high-alloy ferritic matrix. |
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Keywords: | nano-Y2O3 dispersed ferritic steel mechanical alloying microstructure mechanical property pulse plasma sintering |
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