Determination of heat of transformation in a cold-rolled martensitic TiNi alloy

Journal Article · Mon Feb 01 04:00:00 EST 1993 · Metallurgical Transactions, A (Physical Metallurgy and Materials Science); (United States)

DOI:https://doi.org/10.1007/BF02657316· OSTI ID:6137346

Lin, H C ^[1]; Wu, S K ^[2]

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1. Feng Chia Univ., Taiwan (Taiwan, Province of China)
2. National Taiwan Univ. (Taiwan, Province of China)

The authors studied the heat of transformation, [Delta]H, in martensitic transformations in a cold-rolled equiatomic TiNi alloy with differential scanning calorimetry (DSC), X-ray diffraction (XRD), and microhardness measurements. Results of the experiment indicate that the martensite stabilization and stress-induced parent (SIP) B2 phase are introduced when the TiNi martensite is cold rolled at room temperature. The SIP formation seems to be related to the lattice softening phenomenon occurring in the martensite, while the [Delta]H value of the first reverse martensitic transformation decreases enormously for the cold-rolled equiatomic TiNi alloy. The authors are proposing possible explanations for these results: (1) the occurrence of SIP, which reduces the transformable martensite volume; (2) the release of accumulated elastic energy induced by the cold rolling; and (3) the recovery of defects induced by cold rolling and release of the heat of recovery. The authors also found that the retained dislocations can depress the martensitic transformation temperatures and induce the R-phase transformation after the occurrence of the first reverse martensitic transformation.

• OSTI ID: 6137346
• Journal Information: Metallurgical Transactions, A (Physical Metallurgy and Materials Science); (United States), Journal Name: Metallurgical Transactions, A (Physical Metallurgy and Materials Science); (United States) Vol. 24:2; ISSN 0360-2133; ISSN MTTABN
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360101 -- Metals & Alloys-- Preparation & Fabrication
360102* -- Metals & Alloys-- Structure & Phase Studies
ALLOYS
CALORIMETRY
CARBON ADDITIONS
COHERENT SCATTERING
COLD WORKING
DATA
DIFFRACTION
ENTHALPY
EXPERIMENTAL DATA
FABRICATION
HARDNESS
INFORMATION
INTERMETALLIC COMPOUNDS
IRON ALLOYS
MARTENSITE
MATERIALS WORKING
MECHANICAL PROPERTIES
MICROHARDNESS
NICKEL ALLOYS
NUMERICAL DATA
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
REACTION HEAT
SCATTERING
THERMODYNAMIC PROPERTIES
TITANIUM ALLOYS
X-RAY DIFFRACTION