Open AccessThe effect of heat treatment on the structure and high – temperature strength of Fe3Al – based iron aluminide doped by carbon and carbide-forming element
Author(s) -
Martin Švec,
Věra Vodičková,
Pavel Hanus,
Vojtěch Keller
Publication year - 2020
Publication title -
iop conference series. materials science and engineering
Language(s) - English
Resource type - Journals
eISSN - 1757-899X
pISSN - 1757-8981
DOI - 10.1088/1757-899x/723/1/012030
Subject(s) - materials science , aluminide , metallurgy , alloy , laves phase , intermetallic , carbide , annealing (glass) , electron backscatter diffraction , scanning electron microscope , niobium , microstructure , composite material
A structural study as well as the determination of σ 0.2 compression yield stress at high temperatures have been performed on the Fe 3 Al-based iron aluminide doped by Nb (5 at. %) and C (1.5 at. %). The carbon occurrence leads to the formation of three-phase structure. Fe 3 Al matrix, niobium carbides and (Fe, Al) 2 Nb Laves phase were observed in the structure of investigated alloys. Precipitates were inhomogeneously distributed in as cast state alloy. The annealing at 1000 °C for 50 hrs. leads to more homogenously distribution of secondary phase particles and also to refinement of grain size. The strengthening mechanism of material at high temperatures was detected as a combination of strengthening by incoherent precipitates (NbC and Laves phase) and a solid solution hardening by Nb atoms. Effect of two reinforcing mechanisms together with homogeneously precipitate’s distribution increase the values of σ 0.2 compression yield stress about 50 MPa in whole measured temperature range (600 – 800 °C) in comparison to similar intermetallic’s system Fe-Al-Zr-C. Phase composition of the alloy was studied by means of scanning electron microscopy (SEM) equipped by energy dispersive X-ray spectrometer (EDX). The electron backscattered diffraction (EBSD) was used for phase verification and grain size visualization.