Microtexture and macrotexture formation in the containerless solidification of undercooled Ni-18.7 at.% Sn eutectic melts

Journal Article · Tue Feb 01 04:00:00 EST 2005 · Acta Materialia

DOI:https://doi.org/10.1016/j.actamat.2004.10.029· OSTI ID:20637143

Mingjun, Li ^[1]; Nagashio, Kosuke ^[2]; Ishikawa, Takehiko ^[1]; Yoda, Shinichi ^[1]; Kuribayashi, Kazuhiko ^[2]

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1. Japan Aerospace Exploration Agency, Institute of Space and Astronautical Science, Tsukuba Space Center, ISS Science Project Office, 2-1-1 Sengen, Tsukuba, Ibaraki 305-8505 (Japan)
2. Japan Aerospace Exploration Agency, Institute of Space and Astronautical Science, Sagamihara Campus, 3-1-1 Yoshinodai, Sagamihara, Kanagawa 229-8510 (Japan)

The microscopic orientations of Ni-18.7 at.% Sn eutectics solidified from undercooled states, in particular, within an individual eutectic colony and among neighboring eutectic colonies, have been measured with respect to the eutectic Ni{sub 3}Sn and Ni phases; this was done using a scanning electron microscope equipped with the electron backscatter diffraction pattern (EBSP) mapping technique. The EBSPs and inverse pole figures indicate that the Ni{sub 3}Sn intermetallic compound is continuous and well oriented whereas the Ni solid solution is discontinuous and randomly oriented within an anomalous eutectic grain. Further examination reveals that although Ni particulates are random from an overall view, most neighboring Ni grains have small misorientations of less than 10 deg . The specific solidification sequence and the effect of released crystallization heat on subsequent crystallization are further considered, which enables the primary Ni phase to segment into individual grains whereas Ni{sub 3}Sn does not due to higher entropy of fusion. A little rotation or floating within the constrained framework of the crystallizing Ni{sub 3}Sn compound may yield small misorientation angles. The discontinuous Ni particulates and continuous Ni{sub 3}Sn network are of great significance in revealing the anomalous eutectic formation. The orientation among independent eutectic colonies is random owing to the random appearance of nuclei throughout the volume of undercooled melts. The macrotextures of pole figures (PFs) of two eutectic phases are also mapped versus melt undercooling, which can be interpreted well when considering the nucleation frequency, variation of eutectic colony size, microtexture within a single eutectic colony, and the overall microstructure evolution as a function of melt undercooling.

• OSTI ID: 20637143
• Journal Information: Acta Materialia, Journal Name: Acta Materialia Journal Issue: 3 Vol. 53; ISSN 1359-6454; ISSN ACMAFD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BACKSCATTERING
CRYSTALLIZATION
CRYSTALLOGRAPHY
ELECTRON DIFFRACTION
EUTECTICS
INTERMETALLIC COMPOUNDS
MICROSTRUCTURE
NICKEL COMPOUNDS
ORIENTATION
PARTICULATES
SCANNING ELECTRON MICROSCOPY
SOLID SOLUTIONS
SOLIDIFICATION
TIN COMPOUNDS