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Expansion behaviour of Superinvar in the vicinity of martensite transformation temperature
Author(s) -
Distl Josef Siegfried,
Juranek HansJoachim,
Luichtel Georg
Publication year - 2001
Publication title -
steel research
Language(s) - English
Resource type - Journals
eISSN - 1869-344X
pISSN - 0177-4832
DOI - 10.1002/srin.200100144
Subject(s) - transformation (genetics) , martensite , materials science , metallurgy , thermodynamics , forensic engineering , condensed matter physics , engineering , physics , chemistry , microstructure , biochemistry , gene
Superinvar with mass contents of 31 % Ni and 5 % Co can show first traces of the γ–α transformation as far as 10 K above the Ms‐temperature that is established by continuous cooling dilatometry. By thermal cycling to a desired operation temperature in this temperature region, after three cycles the material is stable and does not expand any more unless the temperature is decreased further. The CTE of Superinvar increases by about 0.3 · 10 −6 K −1 if the Ms‐temperature is reached. Heavy hot work slightly expands the temperature range for the use of Superinvar, even in the soft annealed condition. Normal Invar does not show any unexpected effects in the temperature regime examined.