Microstructural stability of the intermetallic Ti–45Al–2W–0.5Si–0.5B in the 800–980 °C temperature range

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Vol. 354; no. 1; pp. 97 - 105
• Main Authors: Zhou, L.Z., Lupinc, V., Guo, J.T.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01-08-2003; Elsevier
• Subjects: Applied sciences; Constant-composition solid-solid phase transformations: polymorphic, massive, and order-disorder; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; High-temperature structural materials; Intermetallics; Materials science; Metals. Metallurgy; Microstructure; Phase diagrams and microstructures developed by solidification and solid-solid phase transformations; Physics; Thermal stability; TiAl; High-temperature structural materials; Intermetallics; Microstructure; Thermal stability; TiAl; Intermetallic compounds; Phase transformations; Ternary alloys; Equiaxed structure; s: Intermetallics; Experimental study; Silicon additions; Titanium alloys; Lamellar structure; Aluminium alloys; Impurities; Aging; Boron additions; Tungsten alloys; Subsurface; Transition element alloys
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/S0921-5093(02)00918-8

γ-TiAl intermetallic Ti–45Al–2W–0.5Si–0.5B was exposed in the temperature range of 800–980
°C, well over its intended application range, for up to 1000 h to test its thermal stability limit. It was found that, the fine α
2 laths could be broken down by growth of equiaxed γ grains, transformation of α
2 to B2 phase, and coalescence of α
2 laths. With increasing of temperature, needle-like B2 phase became spheral, and its volume fraction increased due to the transformation of α
2 to B2 phase. Addition of boron was demonstrated to be beneficial to the thermal stability of the lamellar structure, by the way of comparison to its boron-free counterpart ABB-2 alloy. Subsurface evolution during long-term aging was also investigated.