Phase stability in (Ni, Pt) 3Al alloys

• Published in: Scripta metallurgica et materialia 1994-12, Vol.31 (11), p.1461-1464
• Main Authors: Kamm, Janice L., Milligan, Walter W.
• Format: Article
• Language: English
• Subjects: Alloys; Applied sciences; Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; Metals. Metallurgy; Physics; Structure of solids and liquids; crystallography; Structure of specific crystalline solids
• ISSN: 0956-716X
• DOI: 10.1016/0956-716X(94)90056-6

Some LI2 materials (e.g. Ni3Al) exhibit increase in strength with temperature while others (e.g. Pt3Al) show a decrease. In this study, pseudobinary alloys based on (Ni,Pt)3Al were prepared to test their mechanical behavior as a function of temperature and observe the resulting dislocation structures. A new ternary tetragonal phase of the LIo type, Pt2NiAl, was found in the Al-Ni-Pt system. It is further ordered due to the preference of Ni for the (001) face sites. The same unit cell was previously observed in Pt2CuAl. At 25% Al, the tetragonal phase first appears at 26% Pt, and the single phase tetragonal field exists at least from 37-50% Pt. The phase boundary between single phase LI0 and two phase LI2+LIo is between 33 and 36% Pt. The single phase LIo field likely extends nearly to Pt3Al. Solubility of Pt in Ni3Al at fixed Al concentration was found to be 25% at 1373K which is higher than the currently accepted value of 18.75%.