Martensitic transformations, microstructure, and mechanical workability of TiPt

Autor: L.A. Cornish, Michael B. Cortie, M. J. Witcomb, T. Biggs
Rok vydání: 2001
Předmět:
Zdroj: Metallurgical and Materials Transactions A. 32:1881-1886
ISSN: 1543-1940
1073-5623
DOI: 10.1007/s11661-001-0001-5
Popis: The TiPt phase with the B2 structure has been reported to undergo a reversible displacive transformation to B19 martensite at about 1000 °C. This system could, therefore, serve in principle as the basis of a high-temperature shape-memory alloy (SMA). However, very few additional details of the B2 and B19 forms of TiPt have been published. In the present work, the B19→B2 transformation temperatures previously reported are confirmed, but the B2→B19 temperatures are found to be about 40 °C lower than previously accepted. The hardness of B19 martensite shows a minimum at a stoichiometry of ∼50 at. pct Pt. Between 45 and ∼50 at. pct Pt, the B2↔B19 transformations appear to take place in a complex sequence, with up to two intermediate phases being stable over a range of about 50 °C. No evidence for this intermediate phase was found for Pt contents from 50 to 56 at. pct Pt. It is clear that a Pt content of about 50 at. pct marks a significant change in the nature of the TiPt phase and its martensite or martensites. It was also found that TiPt has a slightly wider stability range than is shown in the current phase diagram, extending from 45 to 56 at. pct Pt at 1300 °C.
Databáze: OpenAIRE
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