Transmission electron microscopy identification of a new Ti–Al–Fe intermetallic compound
A new intermetallic phase has been discovered in the Ti–Al–Fe system. It was first found in a commercial ferrotitanium alloy and then confirmed in a specially prepared experimental alloy. Its crystal structure and chemical composition were investigated using various transmission electron microscopy (TEM) techniques, namely selected area and convergent beam electron diffraction, high-resolution lattice imaging, energy-dispersive X-ray spectroscopy and electron energy-loss spectroscopy (EELS). TEM investigations were complemented by other characterization techniques—scanning electron microscopy, electron-probe microanalysis with wavelength spectrometers, X-ray diffraction and scanning Auger microscopy, as well as quantitative metallography and microhardness measurements. The compound contains 68–74 at.% Ti, 20–24 at.% Fe and 3.5–7 at.% Al. Its crystal lattice is body-centred orthorhombic with periods a ≈ b and c/a ≈ 1.04. The lattice parameters are about four times larger than those of β-Ti (bcc with a = 0.325 nm) and of the TiFe intermetallic (CsCl-type structure with a = 0.298 nm). Apparently, the crystal unit cell of the compound is composed of 4 × 4 × 4 body-centred subcells and contains 128 atoms; the Pearson symbol of the crystal structure is oI128. The new phase was designated β2, thus hinting at its possible relation to β-Ti.
KeywordsElectron Diffraction Pattern Microstructural Component Wavelength Spectrometer Foil Edge Convergent Beam Diffraction Pattern
This research was undertaken as a core project in the Advanced Materials Program at CANMET Materials Technology Laboratory (Dr. Jason Lo, Program Manager). The ferrotitanium alloy was provided by the Ivaco Rolling Mills, L’Original, ON, Canada. A number of people at CANMET provided experimental support: Ms. Catherine Bibby prepared TEM specimens, Dr. Jian Li helped with EPMA measurements, Dr. John Wilson performed X-ray diffractometry, Mr. John Neima carried out Auger spectroscopy, Ms. Pei Liu assisted with metallography and microhardness measurements, and Mr. Jacob Kruszewski and Ms. Ruby Zhang helped with preparation of the experimental alloy and heat treatment.
- 7.Gorzel A, Palm M, Sauthoff G (1999) Z Metallkunde 90:64Google Scholar
- 10.Raghavan V (1987) Phase diagrams of ternary iron alloys. Part 1. ASM International, Metals Park, OH, pp 9–21Google Scholar
- 11.Kornilov II, Pylaeva EN, Volkova MA (1958) Russian J Inorg Chem 3, 3(6):169Google Scholar
- 12.Volkova MA, Kornilov II (1970) Russian metall (Metally) 3:134; (1971) 1:137Google Scholar
- 13.Markiv VY, Burnashova VV, Ryabov VR (1973) Metallofizika 46:103Google Scholar
- 15.Massalski TB (1990) Binary alloy phase diagrams. ASM International, Metals Park OH, pp 2705–2708Google Scholar
- 16.NIST/Sandia/ICDD Electron Diffraction Database (1997) Newtown square. ICDD, PA Google Scholar
- 18.Williams DB, Carter CB (1996) Transmission electron microscopy. Plenum Press, New YorkGoogle Scholar
- 20.Dew-Hughes D (1980) Metall Trans 11A:1219Google Scholar
- 21.Polmear IJ (1989) Light alloys: metallurgy of the light metals, 2nd edn. Arnold, LondonGoogle Scholar