Evolution of microstructures in the nickel modified titanium trialuminides near the L1{sub 2} phase field
- Univ. of Waterloo, Ontario (Canada). Dept. of Mechanical Engineering
This study focuses upon the evolution of microstructures during solidification processing of several intermetallic alloys around the L1{sub 2} phase in the Al-rich corner of the Al-Ti-Ni ternary system. The alloys were produced by double induction melting and subsequent homogenization followed by furnace cooling. The microstructure was characterized by means of optical and scanning electron microscopy with energy-dispersive spectroscopy (EDS) analysis and X-ray diffraction. The microstructural evolution in homogenized alloys was dependent on both nickel and titanium content. Very fine precipitates of Al{sub 2}Ti were observed within the L1{sub 2} phase in alloys containing 62 to 65 at. pct Al and at least 25 at. pct Ti. The Al{sub 2}Ti precipitates are stable at least up to 1,000 C and undergo complete dissolution at 1,200 C. In alloys containing around 66 at. pct Al and 25 to 31 at. pct Ti, the Al-Ti-Ni ternary system is proposed, taking into account the existence of Al{sub 2}Ti, Al{sub 11}Ti{sub 5}, Al{sub 5}Ti{sub 2}, and Al{sub 3}Ti in equilibrium with the L1{sub 2} phase. It seems that at room temperature, the L1{sub 2} phase field for homogenized alloys is extremely small. It will be practically impossible to obtain a single-phase microstructure at room temperature in the Al-Ti-Ni ternary alloys after homogenization at 1,000 C followed by furnace cooling.
- OSTI ID:
- 203514
- Journal Information:
- Metallurgical Transactions, A, Journal Name: Metallurgical Transactions, A Journal Issue: 1 Vol. 27; ISSN 0360-2133; ISSN MTTABN
- Country of Publication:
- United States
- Language:
- English
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