NiTi and NiTi-TiC composites. Part 1: Transformation and thermal cycling behavior

Journal Article · Wed Nov 01 04:00:00 EST 1995 · Metallurgical Transactions, A

DOI:https://doi.org/10.1007/BF02669642· OSTI ID:131472

Mari, D; Dunand, D C ^[1]

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1. Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Materials Science and Engineering

The transformation behavior of titanium-rich NiTi containing 0 vol pct, 10 vol pct equiaxed TiC particles was studied by differential scanning calorimetry. The thermoelastic phase transformation of the unreinforced matrix exhibits multiple steps. Upon multiple transformation cycles, the rhombohedral phase (R phase) appears and all transformation temperatures decrease. The TiC particles inhibit the R phase and also lower some of the transformation temperatures. These effects can be explained by the internal misfit stresses resulting from both thermal expansion and transformation mismatch between matrix and reinforcement. The measured transformation enthalpy of bulk and reinforced NiTi is discussed in light of a thermodynamical model, taking into account the elastic energy stored upon cycling. The model indicates that a significant fraction of the matrix is stabilized and thus does not contribute to the transformation enthalpy.

• Sponsoring Organization: USDOE
• OSTI ID: 131472
• Journal Information: Metallurgical Transactions, A, Journal Name: Metallurgical Transactions, A Journal Issue: 11 Vol. 26; ISSN 0360-2133; ISSN MTTABN
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
AUSTENITE
CALORIMETRY
COMPOSITE MATERIALS
ENTHALPY
MARTENSITE
MATHEMATICAL MODELS
NICKEL ALLOYS
PHASE TRANSFORMATIONS
PRECIPITATION
RESIDUAL STRESSES
STRESSES
THERMAL EXPANSION
TITANIUM ALLOYS
TITANIUM CARBIDES
TRIGONAL LATTICES